Dietary supplement use in ambulatory cancer patients: a survey on prevalence, motivation and attitudes

Abstract

Purpose
Patients with cancer often believe dietary supplements (DS) such as micronutrients and botanical products to be health supporting and non-toxic despite growing concerns regarding potential pharmacological interactions. Studies on the prevalence of DS use among patients with cancer are heterogeneous and mainly conducted at university-based cancer centers. This survey focused on a particular cancer patient group treated in an ambulatory setting without regular access to professional nutritional counselling.

Methods
Patients with a history of cancer or hematological malignancy were included in this survey. A self-reported questionnaire was used to evaluate the different aspects of DS use, changes in dietary habits and patients’ demographic characteristics.

Results
Almost every second patient reported using DS (47.2%). Women (56.3%), patients with an academic degree (56.0%) and non-smokers (84.8%) were more inclined to use DS. Along with magnesium (16.6%), calcium (14.3%), multivitamins (12.0%) and vitamin C (9.4%), use of herbal supplements (12.6%) was common. Women (84.8% vs. 74.9% of men, p = < 0.001) and patients younger than 65 years (84.4% vs. 77.2% of patients > 65 y, p = 0.002) sought dietary advice more often. Support of the immune system was the main reason for DS use (26.4%) and a relevant number of patients (49.6%) reported to have changed their dietary habits following cancer diagnosis.

Conclusion
DS use is common among patients with cancer treated in an ambulatory setting. This finding should encourage oncologists to implement detailed questioning about DS use and dietary habits to prevent potential interactions and offer substantial advice.

Full text

Vol.:(0123456789)
1 3
Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
https://doi.org/10.1007/s00432-021-03594-7
ORIGINAL ARTICLE – CANCER RESEARCH
Dietary supplement use inambulatory cancer patients: asurvey
onprevalence, motivation andattitudes
MajaTank1,2· KristinaFranz2,3· EmanueleCereda4· KristinaNorman2,3,5
Received: 1 March 2021 / Accepted: 10 March 2021 / Published online: 6 April 2021
© The Author(s) 2021
Abstract
Purpose Patients with cancer often believe dietary supplements (DS) such as micronutrients and botanical products to be
health supporting and non-toxic despite growing concerns regarding potential pharmacological interactions. Studies on
the prevalence of DS use among patients with cancer are heterogeneous and mainly conducted at university-based cancer
centers. This survey focused on a particular cancer patient group treated in an ambulatory setting without regular access to
professional nutritional counselling.
Methods Patients with a history of cancer or hematological malignancy were included in this survey. A self-reported
questionnaire was used to evaluate the different aspects of DS use, changes in dietary habits and patients’ demographic
characteristics.
Results Almost every second patient reported using DS (47.2%). Women (56.3%), patients with an academic degree (56.0%)
and non-smokers (84.8%) were more inclined to use DS. Along with magnesium (16.6%), calcium (14.3%), multivita-
mins (12.0%) and vitamin C (9.4%), use of herbal supplements (12.6%) was common. Women (84.8% vs. 74.9% of men,
p = < 0.001) and patients younger than 65years (84.4% vs. 77.2% of patients > 65 y, p = 0.002) sought dietary advice more
often. Support of the immune system was the main reason for DS use (26.4%) and a relevant number of patients (49.6%)
reported to have changed their dietary habits following cancer diagnosis.
Conclusion DS use is common among patients with cancer treated in an ambulatory setting. This finding should encourage
oncologists to implement detailed questioning about DS use and dietary habits to prevent potential interactions and offer
substantial advice.
Keywords Dietary supplements· Dietary habits· Patients with cancer· Nutritional counselling
Introduction
Use of dietary supplements (DS) such as vitamins, trace ele-
ments, minerals and botanical products has become increas-
ingly popular among patients with cancer, believing DS to
be non-toxic and health-supporting and therefore to be used
as self-medication (Bailey etal. 2011; Li etal. 2010). Stud-
ies estimate the prevalence of DS use ranging from 18 to
95% depending on the patient population, tumor stage and
cultural background (Du etal. 2020; Luo and Asher 2018;
Molassiotis etal. 2005; Wilkinson and Stevens 2014).
Despite the popularity of DS, the use in disease is contro-
versially discussed among health professionals and scientists
due to increasing evidence regarding potential interactions
with conventional therapies, leading to either an increase
in toxicity or loss of effectiveness. Potential harm is also
derived by the fact that patients often do not disclose the
* Kristina Norman
kristina.norman@charite.de
1 Medizinisches Versorgungszentrum Tempelhof Oncology,
Berlin, Germany
2 Department ofGeriatrics, Charité—Universitätsmedizin
Berlin, Corporate Member ofFreie Universität Berlin
andHumboldt—Universität zu Berlin, Reinickendorfer
Str. 61, 13347Berlin, Germany
3 Institute ofNutritional Science, University ofPotsdam,
Potsdam, Germany
4 Clinical Nutrition andDietetics Unit, Fondazione IRCCS
Policlinico San Matteo, Pavia, Italy
5 Department ofNutrition andGerontology, German Institute
ofHuman Nutrition Potsdam—Rehbrücke, Nuthetal,
Germany
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1918 Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
use of DS to their doctors (Davis etal. 2012; Levy etal.
2018). Nevertheless, studies show a highly unmet need for
a consultation about complementary alternative medicine,
and DS in particular (Horneber etal. 2018).
A special feature of the German health system is the
decentralized patient care system situated at specialized
doctor’s offices. In fact, a significant proportion of patients
with cancer in Germany are treated in such ambulatory set-
tings. In contrast to many hospitals and comprehensive can-
cer centers, they do not offer a routine dietary counselling.
Therefore, in this study we investigated the prevalence
of DS use including herbal and botanical supplements in
patients with cancer treated in an ambulatory setting with
respect to demographic characteristics as well as clinical
features such as type of disease, disease duration and type
of therapy approach. Moreover, the study aims to assess the
attitude of patients towards DS and their motivation for DS
use as well to gather information regarding the sources of
dietary information in ambulatory patients with cancer.
Methods
Study population
A cross-sectional survey was conducted in patients with
cancer, seeking care at three ambulatory cancer care cent-
ers, between September 2011 and October 2012 and Sep-
tember 2017 and December 2019. Inclusion criteria were
a history of solid tumor disease, malignant hematological
disease or chronic hematological non-malignant condition
and age ≥ 18years. Patients were classified according to the
administered therapy: any kind of oncological medication,
best supportive care, surgical intervention only, radiother-
apy only and no intervention at all (watch and see strategy).
All participants gave written informed consent. The study
was reviewed and approved by the Ethics Committee of the
Charité University Hospital, Berlin.
Data collection
To assess different aspects of DS use, a questionnaire was
developed containing open-end and closed questions as well
as multiple-choice questions, allowing multiple answers. The
main part of the questionnaire comprises questions regarding
the use of DS, frequency and duration of DS use, type of DS
and dosage. Different kinds of vitamins, minerals and trace
elements are listed as well as botanical or herbal supplements,
special teas and immune-stimulating supplements. The sec-
ond part focuses on sources of information regarding DS use
and patients’ motivation for using DS. Moreover, we asked for
changes in dietary habits including preferences or avoidance
of certain foods since cancer diagnosis. The last part of the
questionnaire asks for demographic and clinical data, such as
diagnosis, time since diagnosis, tumor stage, treatment history
and comorbidities. The questionnaire was tested in a pre-test
involving 20 patients with cancer to prove practicability and
comprehensibility—in particular, the understanding of specific
terms. The test patients were also interviewed about their DS
use (intake, frequency and duration) and asked to bring their
products to compare results from the questionnaire and the
interview.
Statistical analysis
All statistical analyses were performed using IBM SPSS
Version 23 and 25. For nominal variables, results were
described by frequencies (n) and percentage (%). χ2 test and
Fisher’s exact test were used to compare categorical parame-
ters. Continuous variables were reported as mean and stand-
ard deviation (SD) or median and interquartile range (IQR).
Two-group and multiple-group comparisons were performed
using the Student’s t test and ANOVA or the non-parametric
tests Mann–Whitney U and Kruskal–Wallis. p values below
0.05 were a priori considered statistically significant.
Results
A total of 1217 (51.3% female) out of 1452 patients
(Table1) completed the questionnaire which reflects an
83.8% response rate. 54.5% of patients suffered from solid
cancer with a median duration of disease of 18months
(5–44months). Colorectal cancer was the most common
disease followed by breast cancer and other cancer of the
genital organs. 40.1% of patients had advanced or meta-
static disease. 39.2% of patients had hematological neo-
plasms with a median duration of disease of 29months
(8–70months). Within this group, Non-Hodgkin lymphoma,
multiple myeloma and myeloproliferative neoplasm were
the most frequently diagnosed. Furthermore, 6.3% reported
other chronic hematological non-malignant conditions such
as chronic autoimmune thrombocytopenia (2.6%) and mono-
clonal gammopathy of unknown origin (3.3%) with a median
duration of disease of 38months (16–70months). Regarding
the different therapy strategies, the following distribution
pattern was found: 71.9% of patients received some kind of
oncological medication, 6.6% reported to be on best support-
ive care, 4.6% underwent surgical intervention only, 2.4%
had radiotherapy only and 12.2% did not receive any kind
of intervention at all (watch and see strategy).
Frequency ofDS use
Of 1217 patients, 47.2% reported using DS at study entrance,
4.5% of patients had taken DS until recently and 48.1%
denied use of DS.
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1919Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
Overall, women and patients with an academic back-
ground as well as non-smokers reported using DS more
frequently (see Table1). Participants with chronic hemato-
logical non-malignant condition used DS more often than
patients with solid tumors or hematological neoplasms as
follows: 61.8% vs. 47.3% vs. 45.0%, p = 0.035).
Within the group of DS users, 41.5% started DS use after
cancer diagnosis whereas 37.1% had used DS regularly and
19.2% occasionally before cancer diagnosis. The majority of
patients reported DS use daily (64.8%) and for longer than
12months (64.5%).
We found sex-specific differences only within the group
of patients with solid tumor disease, which was related to the
cohort with cancer of the genital tract, including breast can-
cer (Table2). Duration of disease differed between DS users
and non-users (24.0months [IQR 7–62] vs. 21.0months
[IQR 6–50], p = 0.045), whereas tumor stage (p = 0.170) or
patients’ reported therapeutic approach did not (p = 0.980).
Type ofDS use
Magnesium and calcium supplementation was most fre-
quently reported followed by herbal and botanical supple-
ments, multivitamins, vitamin D and the vitamin B group,
which is shown in summary as well as according to sex
and age in Table3. Only a minority of participants (< 5%)
gave detailed dosage information of DS products. Detailed
analysis of the reported types of herbal and botanical
supplements revealed more than 50 different kinds of
products, e.g. curcumin preparations, milk thistle, black
cumin oil, St John’s wort, mistletoe, seaweed extract (data
not shown).
Women reported the use of herbal and botanical sup-
plements, tea and immune-stimulating supplements more
often than men. We also found a difference between age
groups, as younger patients used selenium more often,
and older patients used magnesium more frequently (see
Table3).
Patients’ attitude andmotivation forDS use
Pre-formulated statements were used to assess attitude
towards DS use in all participants as well as motivation in
DS users. Multiple answers were allowed. As can be seen
in Fig.1, the most frequent attitude was to treat nutritional
deficiencies, whereas disapproval due to health risk con-
cerns was mentioned least.
The following statements regarding patients’ motivation
were selected in decreasing frequencies: support of the
immune system (26.4%), prevention of nutritional defi-
ciencies (18.8%), improvement of quality of life (15.7%),
defeat cancer (11.8%), improvement of side effects (9.3%),
complement conventional therapy (8.6%) and stop disease
progression (6.7%). There was no sex-specific difference
except for the statement “support of the immune system”
and “prevention of nutritional deficiencies” (see Fig.2).
Table 1 Sociodemographic
characteristics and lifestyle
factors of the study population
DS users were defined as patients who used ≥ 1 DS, regularly. Patients who stopped their DS intake at
study entrance were classified in the interrupted DS user group. Data are given as mean ± SD or as absolute
values (and %) and were performed using the ANOVA and the χ2 test
DS dietary supplements, BMI body mass index
*Missing values: 15 (1.2%), **missing values: 18 (1.5%)
Characteristics All
n = 1217
DS users
n = 574
Discontinued DS use
n = 55
Non DS users
n = 585
p value
Age (years) 67.6 ± 12.9 68.0 ± 12.5 65.8 ± 13.3 67.4 ± 13.2 0.425
Sex, n (%)
Female 624 (51.3) 324 (56.3) 32 (58.2) 267 (45.6) 0.001
Male 593 (48.7) 251 (43.7) 23 (41.8) 318 (54.4)
Current living situation, n (%)
Living alone 373 (30.9) 174 (30.6) 16 (29.6) 182 (31.2) 0.958
Living with partner 835 (69.1) 394 (69.4) 38 (70.4) 401 (68.8)
Education level*, n (%)
Non-academic 993 (82.6) 456 (79.6) 45 (83.3) 492 (85.6) 0.028
Academic 209 (17.4) 117 (20.4) 9 (16.7) 83 (14.4)
Smoking status**, n (%)
Non smoker 974 (81.2) 480 (84.8) 39 (72.2) 455 (78.6) 0.023
Previous smoker 18 (1.5) 9 (1.6) 1 (1.9) 8 (1.4)
Current smoker 207 (17.3) 77 (13.6) 14 (25.9) 116 (20.0)
BMI (kg/m2)25.7 ± 4.8 25.4 ± 4.9 25.4 ± 4.9 25.9 ± 4.6 0.231
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1920 Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
Table 2 Type of solid tumor disease and hematological neoplasms according to sex and use of DS (n = 1217)
Data are presented as frequencies (%). Percentages refer to type of disease
DS dietary supplements
*p values were calculated between sex with Fisher’s exact test
Type of disease Women Men p value*
DS users
n = 323
Discontinued
DS use
n = 32
Non DS users
n = 268
DS users
n = 251
Discontinued
DS use
n = 23
Non DS users
n = 317
Solid tumor location, n (%)
Genital tract, breast or prostate 86 (58.5) 4 (2.7) 57 (38.8) 20 (37.7) 3 (5.7) 30 (56.6) 0.022
Lung or respiratory tract 20 (57.1) 3 (8.6) 12 (34.3) 22 (48.9) 0 23 (51.1) 0.060
Gastrointestinal tract 38 (48.7) 7 (9.0) 33 (42.3) 63 (41.7) 7 (4.6) 81 (53.6) 0.164
Hepatobiliary or pancreatic tract 11 (42.3) 4 (15.4) 11 (42.3) 16 (37.2) 1 (2.3) 26 (60.5) 0.086
Kidney or bladder 3 (30.0) 1 (10.0) 6 (60.0) 7 (53.8) 1 (7.7) 5 (38.5) 0.583
Head and neck 2 (66.7) 0 1 (33.3) 8 (50.0) 1 (6.3) 7 (43.8) 1.000
Other 13 (46.4) 1 (3.6) 14 (50.0) 4 (28.6) 1 (7.1) 9 (64.3) 0.395
Hematological neoplasms, n (%)
Non-Hodgkin lymphoma 40 (56.3) 4 (5.6) 27 (38.0) 26 (44.8) 2 (3.4) 30 (51.7) 0.277
Multiple myeloma 21 (45.7) 2 (4.3) 23 (50.0) 26 (55.3) 1 (2.1) 20 (42.6) 0.592
Myeloproliferative neoplasm 20 (38.5) 1 (1.9) 31 (59.6) 13 (32.5) 0 27 (67.5) 0.808
Chronic lymphocytic leukemia 17 (63.0) 0 10 (37.0) 17 (44.7) 2 (5.3) 19 (50.0) 0.304
Myelodysplastic syndrome 10 (37.0) 2 (7.4) 15 (55.6) 9 (34.6) 1 (3.8) 16 (61.5) 1.000
Acute leukemia 6 (60.0) 0 4 (40.0) 5 (29.4) 1 (5.9) 11 (64.7) 0.299
Hodgkin lymphoma 2 (18.2) 1 (9.1) 8 (72.7) 2 (40.0) 0 3 (60.0) 0.698
Chronic hematologic disease 34 (66.7) 2 (3.9) 15 (29.4) 13 (50.0) 2 (7.7) 11 (42.3) 0.362
Table 3 Type and frequency of DS use according to sex and age categories in all patients
Data presented as frequencies (%). p values are calculated with χ2 test. Multiple answers allowed
DS dietary supplements
Types of DS All
n = 1217
Sex p value Age p value
Women
n = 624
Men
n = 593
≤ 65 y
n = 456
> 65 y
n = 760
Vitamins, n (%)
Vitamin D 133 (10.9) 78 (12.5) 55 (9.3) 0.071 45 (9.9) 87 (11.4) 0.392
Vitamin B group 132 (10.8) 76 (12.2) 56 (9.4) 0.125 42 (9.2) 90 (11.8) 0.153
Vitamin C 115 (9.4) 62 (9.9) 53 (8.9) 0.552 43 (9.4) 72 (9.5) 0.980
Vitamin E 41 (3.4) 21 (3.4) 20 (3.4) 0.994 14 (3.1) 27 (3.6) 0.652
Multivitamins, n (%) 146 (12.0) 72 (11.5) 74 (12.5) 0.614 57 (12.5) 89 (11.7) 0.682
Micronutrients and trace elements, n (%)
Magnesium 202 (16.6) 105 (16.8) 97 (16.4) 0.826 63 (13.8) 139 (18.3) 0.042
Calcium 174 (14.3) 94 (15.1) 80 (13.5) 0.433 57 (12.5) 117 (15.4) 0.163
Zinc 69 (5.7) 41 (6.6) 28 (4.7) 0.163 24 (5.3) 45 (5.9) 0.631
Iron 62 (5.1) 36 (5.8) 26 (4.4) 0.272 23 (5.0) 39 (5.1) 0.946
Selenium 50 (4.1) 29 (4.6) 21 (3.5) 0.331 27 (5.9) 23 (3.0) 0.014
Immune stimulating supplements, n (%) 75 (6.2) 47 (7.5) 28 (4.7) 0.042 34 (7.5) 41 (5.4) 0.148
Omega-3 fatty acids, n (%) 69 (5.7) 33 (5.3) 36 (6.1) 0.555 26 (5.7) 43 (5.7) 0.974
Herbal and botanical supplements, n (%) 153 (12.6) 102 (16.3) 51 (8.6) 0.001 61 (13.3) 92 (12.2) 0.603
Tea, n (%) 200 (16.4) 124 (19.9) 76 (12.8) 0.001 78 (17.1) 122 (16.1) 0.632
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1921Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
Sources ofadvice onDS use
In summary, 79.7% of all participants reported having
received or acquired information on the influence of nutri-
tion and DS on cancer disease from at least one source
whereas approximately a fifth of patients denied receiving
any kind of nutritional information. Women (84.8% vs.
74.9%, p = < 0.001) and patients younger than 65years
(84.4% vs. 77.2%, p = 0.002) sought advice more often.
Depending on the source of advice, there were differ-
ences regarding the use of DS (see Table4). Patients who
acquired information from print media, internet and TV
reported using DS significantly more than uninformed
patients. The same applies to patients, who were advised
by their nutritionist/dietician, pharmacist and homeopath
or by other health professionals, whereas no difference was
found within the groups of patients, who received advice
from their oncologist or physician or those who stated to
be uninformed.
Changes indietary habits
Almost half of all participants (49.6%) reported a change of
dietary habits upon cancer diagnosis, with the highest per-
centage in women (55.6% vs. 44.4%, p = 0.003). A change of
dietary habits was more frequent in patients taking DS (59.9
vs. 39.1%, p < 0.001). 33% of participants reported to give
preference to certain foods of which fruits, including citrus
fruits, were the most frequently mentioned (54.7%). 35.7%
of participants reported to avoid certain kinds of food such
as meat, alcohol, sugar and fatty foods. Cancer-specific diets
did not seem to play a major role as only 2.4% of participants
reported following cancer diets (see Fig.3).
Again, sex-specific differences were found in the group
with solid tumor disease (p = 0.007). Women with lung
Fig. 1 Attitudes towards supple-
ment use in DS users
Fig. 2 Reasons for dietary sup-
plement use. Multiple answers
were allowed
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1922 Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
cancer (57.1% vs. 42.9%, p = 0.033), breast cancer or can-
cer of the genital tract (53.7% vs. 37.7%, p = 0.046), but
also with myelodysplastic syndrome (44.4% vs. 19.2%,
p = 0.049) changed their dietary habits significantly more
often than men. Moreover, 58.8% of the participants younger
than 65years reported changes in dietary habits compared
to 44% in the cohort older than 65, (p = < 0.001). Patients
with solid tumor disease (55.3%, p = < 0.001) and patients
with a history of oncological medication (52.4%, p = 0.004)
changed their dietary habits more often, whereas marital
status only had a borderline effect (single 53.8% vs. 47.7%,
p = 0.050). No difference was identified between changes of
dietary habits and duration of disease (p = 0.367), academic
degree (p = 0.339), smoking status (p = 0.574) and tumor
stage, respectively (p = 0.766). Figure3 shows changes of
dietary habits since diagnosis.
Discussion
In the context of the growing popularity of DS such as
micronutrients as well as complementary and alternative
medicine related supplements (e.g. herbal and botanical
supplements) on the one hand and increasing evidence of
potential toxic side effects due to pharmacokinetic inter-
actions on the other hand, assessing dietary supplement
Table 4 Most frequent sources
of advice and DS use
Data presented as frequencies (%). p values are calculated with Fisher’s exact test. Multiple answers
allowed
DS dietary supplements
All
n = 1217
DS users
n = 574
Discontinued
DS users
n = 55
Non DS users
n = 585
p value
Source of information, n (%)
Print media 385 (31.6) 214 (37.2) 30 (54.5) 141 (24.1) < 0.001
Oncologist 362 (29.7) 182 (31.7) 14 (25.5) 166 (28.4) 0.386
Friends or family member 337 (27.7) 194 (33.7) 19 (34.5) 125 (21.4) < 0.001
Primary care physician 332 (27.3) 161 (28.0) 11 (20.0) 160 (27.4) 0.472
Internet, social media 227 (18.7) 137 (23.9) 18 (32.7) 72 (12.3) < 0.001
Nutritionist/Dietician 226 (18.6) 127 (22.1) 16 (29.1) 83 (14.2) < 0.001
TV 222 (18.2) 110 (19.1) 16 (29.1) 96 (16.4) 0.057
Other health care professionals 71 (5.8) 46 (8.0) 3 (5.5) 22 (3.8) 0.007
Homeopath 47 (3.9) 39 (6.8) 3 (5.5) 5 (0.9) < 0.001
Pharmacist 45 (3.7) 31 (5.4) 2 (3.6) 12 (2.1) 0.009
Other 80 (6.6) 46 (8.0) 5 (9.1) 29 (5.0) 0.074
No information received, n (%) 242 (19.9) 74 (12.9) 6 (10.9) 162 (27.7) < 0.001
Fig. 3 Awareness and changes
in dietary habits upon tumour
diagnosis. Multiple answers
were allowed
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1923Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
use has become one focus in research, but not yet in clini-
cal practice. Our study revealed that almost every second
ambulatory patient with cancer used DS which is similar
to previous studies. The majority of patients stated to have
received or acquired advice on the intake of DS and the
most frequently given reason for DS intake was to support
the immune system, followed by prevention of nutritional
deficiencies.
Data on the prevalence of DS use among ambulatory
patients with cancer is limited in number and studies are het-
erogeneous regarding patient cohorts and design (Holzapfel
etal. 2020; Huebner etal. 2014; Konig etal. 2016; Maschke
etal. 2017). The majority of data is acquired from patients
suffering from breast cancer (Drozdoff etal. 2018; Fremd
etal. 2017) and studies are mainly conducted in coopera-
tion with university-based cancer centers. We, therefore,
focused on ambulatory patients with cancer who have no
regular access to dietary counselling. Our findings reveal
that 51.7% of ambulatory patients use, or have used DS.
Similar results in patients with cancer have been described
elsewhere (Alsanad etal. 2016; Jermini etal. 2019; Luo and
Asher 2018; Schuerger etal. 2019). In accordance to some
studies (Alsanad etal. 2016; Friedman etal. 2019; Jermini
etal. 2019; Konig etal. 2016; Schuerger etal. 2019), our
data shows a significantly higher frequency of DS use among
women. This effect was due to the cohort with breast- and
genital cancer disease, and most likely due to women with
breast cancer, who have previously been shown to be highly
motivated to use DS (Ferrucci etal. 2009; Holzapfel etal.
2020; Luo and Asher 2018; Miller etal. 2009). In fact, our
study results show that overall frequency regarding DS use
remains as high as in healthy individuals (Bailey etal. 2011;
Friedman etal. 2019; Li etal. 2010) and is only exceeded
by the groups of cancer survivors and patients with breast
cancer (Drozdoff etal. 2018; Ferrucci etal. 2009; Miller
etal. 2009).
Calcium and magnesium are the most frequently taken
supplements in our survey, which is in accordance with other
studies with cancer patients (Alsanad etal. 2016; Friedman
etal. 2019; Wilkinson and Stevens 2014). One-fifth of our
participants reported taking either multivitamins or vitamin
C, which again is comparable to the previously mentioned
studies (Alsanad etal. 2016; Wilkinson and Stevens 2014).
Use of herbal and botanical supplements was reported in
12.6% of participants, which is in range with other cross-
sectional cancer patient studies (Molassiotis etal. 2005;
Wilkinson and Stevens 2014). Besides other non-vitamin-
non-mineral DS, especially high dose herbal and botani-
cal supplements are suspected to harbour a higher risk for
drug interactions and therefore should not be generally rec-
ommended (Caccialanza etal. 2016; Daenen etal. 2015;
Frenkel etal. 2013; Hsieh etal. 2014; Mazzanti etal. 2015,
2009).
Due to the fact that neither quality nor frequency of die-
tary information could be objectified, conclusions regarding
the influence of nutritional information on patients´ moti-
vation to use DS have to be drawn carefully. We identified
an association between DS use and information by semi-
professional sources and lay sources, but also by nutrition-
ists and pharmacists. This finding may be biased by the fact
that patients who are actively seeking advice may be more
willing to use DS than others and vice versa. Nevertheless,
these findings raise the question about the quality in terms
of evidence-based information on DS use provided by health
professionals and highlight the need for further training and
education regarding this issue. Research groups like the
Competence Network Complementary Medicine in Oncol-
ogy (KOKON) funded by the German Cancer Aid Society
and others, (Guthlin etal. 2020; He etal. 2019; Helmer etal.
2019; Ziemann etal. 2019) are currently working on this
issue to implement evidence-based information on DS and
nutrition and other aspects of complementary medicine into
patient-doctor-communication to prevent harm and improve
treatment compliance and tolerability (Frenkel etal. 2013;
Greenlee etal. 2017; Shalom-Sharabi etal. 2017).
Almost half of the respondents reported to have changed
their dietary habits and wished to eat a „healthier “ diet.
Participants reported eating more vegetables and fruits and
to avoid certain foods. With respect to the well-known toxic
interactions between certain kinds of citrus fruits, e.g. grape-
fruits, bitter oranges and pomegranates, and a growing range
of pharmaceuticals, these findings again underline the need
for a detailed exploration of dietary concerns (de Jong etal.
2015).
Our data is subject to limitations due to the use of a self-
reported questionnaire which harbours the well-known
risk of under- or overestimation. We also cannot exclude
inclusion bias associated with the type of recruitment (vol-
untary). Being aware of study-derived estimates of up to
75% of patients who refrain from disclosing DS use to their
health provider for different reasons, we used a self-admin-
istered questionnaire to assure participants would feel free
to answer without other influence (Levy etal. 2018). As
a consequence, there was no chance to discuss missing or
ambiguous data with the patient, which also may contribute
to false estimation.
Conclusion
As almost every second patient with cancer reported chang-
ing their dietary habits and using DS, our findings empha-
size the need to implement nutritional consultation routinely
into cancer care in the ambulatory setting, as well as to meet
patients’ needs, and to prevent potential interactions with
anticancer therapies.
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1924 Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
Author contributions MT: Data curation, formal analysis, methodol-
ogy, investigation, project administration and writing—original draft.
KF: Formal analysis, visualization, writing—review and editing. EC:
Writing—review and editing. KN: Conceptualization, methodology,
supervision, writing—original draft.
Funding Open Access funding enabled and organized by Projekt
DEAL. This research did not receive any specific grant from funding
agencies in the public, commercial, or not-for-profit sectors.
Availability of data and materials Patients’ data and material belong to
the Charité—Universitätsmedizin Berlin, corporate member of Freie
Universität Berlin, Humboldt—Universität zu Berlin and access is
restricted according to data protection laws. The datasets are available
from the corresponding author on reasonable request.
Declarations
Conflict of interest The authors declare that they have no competing
interests.
Consent for publication All authors read and approved the final manu-
script.
Consent to participate All participants gave written informed consent.
Ethical approval This study was approved by the Ethics Committee of
the Charité University Hospital, Berlin.
Open Access This article is licensed under a Creative Commons Attri-
bution 4.0 International License, which permits use, sharing, adapta-
tion, distribution and reproduction in any medium or format, as long
as you give appropriate credit to the original author(s) and the source,
provide a link to the Creative Commons licence, and indicate if changes
were made. The images or other third party material in this article are
included in the article’s Creative Commons licence, unless indicated
otherwise in a credit line to the material. If material is not included in
the article’s Creative Commons licence and your intended use is not
permitted by statutory regulation or exceeds the permitted use, you will
need to obtain permission directly from the copyright holder. To view a
copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/.
References
Alsanad SM, Howard RL, Williamson EM (2016) An assessment of
the impact of herb-drug combinations used by cancer patients.
BMC Complement Altern Med 16:393. https:// doi. org/ 10. 1186/
s12906- 016- 1372-x
Bailey RL etal (2011) Dietary supplement use in the United States,
2003–2006. J Nutr 141:261–266. https:// doi. org/ 10. 3945/ jn. 110.
133025
Caccialanza R etal (2016) Nutritional support in cancer patients: a
position paper from the Italian Society of Medical Oncology
(AIOM) and the Italian Society of Artificial Nutrition and Metab-
olism (SINPE). J Cancer 7:131–135. https:// doi. org/ 10. 7150/ jca.
13818
Daenen LG etal (2015) Increased plasma levels of chemoresistance-
inducing fatty acid 16:4(n-3) after consumption of fish and fish
oil. JAMA Oncol 1:350–358. https:// doi. org/ 10. 1001/ jamao ncol.
2015. 0388
Davis EL, Oh B, Butow PN, Mullan BA, Clarke S (2012) Cancer
patient disclosure and patient-doctor communication of com-
plementary and alternative medicine use: a systematic review.
Oncologist 17:1475–1481. https:// doi. org/ 10. 1634/ theon colog
ist. 2012- 0223
de Jong J etal (2015) Effect of CYP3A perpetrators on ibrutinib expo-
sure in healthy participants. Pharmacol Res Perspect 3:e00156.
https:// doi. org/ 10. 1002/ prp2. 156
Drozdoff L, Klein E, Kiechle M, Paepke D (2018) Use of biologically-
based complementary medicine in breast and gynecological can-
cer patients during systemic therapy. BMC Complement Altern
Med 18:259. https:// doi. org/ 10. 1186/ s12906- 018- 2325-3
Du M etal (2020) Dietary supplement use among adult cancer sur-
vivors in the United States. J Nutr 150:1499–1508. https:// doi.
org/ 10. 1093/ jn/ nxaa0 40
Ferrucci LM, McCorkle R, Smith T, Stein KD, Cartmel B (2009)
Factors related to the use of dietary supplements by cancer sur-
vivors. J Altern Complement Med 15:673–680. https:// doi. org/
10. 1089/ acm. 2008. 0387
Fremd C etal (2017) Use of complementary and integrative medicine
among German breast cancer patients: predictors and implica-
tions for patient care within the PRAEGNANT study network.
Arch Gynecol Obstet 295:1239–1245. https:// doi. org/ 10. 1007/
s00404- 017- 4348-2
Frenkel M etal (2013) Integrating dietary supplements into cancer
care. Integr Cancer Ther 12:369–384. https:// doi. org/ 10. 1177/
15347 35412 473642
Friedman J, Birstler J, Love G, Kiefer D (2019) Diagnoses associated
with dietary supplement use in a national dataset. Complement
Ther Med 43:277–282. https:// doi. org/ 10. 1016/j. ctim. 2019. 02.
016
Greenlee H etal (2017) Clinical practice guidelines on the evidence-
based use of integrative therapies during and after breast cancer
treatment. CA Cancer J Clin 67:194–232. https:// doi. org/ 10. 3322/
caac. 21397
Guthlin C etal (2020) KOKON: A Germany-Wide Collaborative
Research Project to identify needs, provide information, foster
communication and support decision-making about complemen-
tary and alternative medicine in oncology. Complement Med Res
27:105–111. https:// doi. org/ 10. 1159/ 00050 2945
He X etal (2019) ALOHA: developing an interactive graph-based visu-
alization for dietary supplement knowledge graph through user-
centered design. BMC Med Inform Decis Mak 19:150. https:// doi.
org/ 10. 1186/ s12911- 019- 0857-1
Helmer SM, Rogge AA, Fischer F, Pach D, Horneber M, Roll S, Witt
CM (2019) Evaluation of a blended-learning training concept to
train oncology physicians to advise their patients about comple-
mentary and integrative medicine (KOKON-KTO): study protocol
for a prospective, multi-center, cluster-randomized trial. Trials
20:90. https:// doi. org/ 10. 1186/ s13063- 019- 3193-y
Holzapfel CKA, Jaeckel B, Martignoni M, Hauner D, Hauner H (2020)
Ernährungsformen und Einnahme von Nahrungsergänzungsmit-
teln bei Patienten mit Tumorerkrankungen
Horneber M, van Ackeren G, Fischer F, Kappauf H, Birkmann J (2018)
Addressing unmet information needs: results of a clinician-led
consultation service about complementary and alternative medi-
cine for cancer patients and their relatives. Integr Cancer Ther
17:1172–1182. https:// doi. org/ 10. 1177/ 15347 35418 808597
Hsieh YW, Huang CY, Yang SY, Peng YH, Yu CP, Chao PD, Hou YC
(2014) Oral intake of curcumin markedly activated CYP 3A4:
invivo and ex-vivo studies. Sci Rep 4:6587. https:// doi. org/ 10.
1038/ srep0 6587
Huebner J etal (2014) User rate of complementary and alternative
medicine (CAM) of patients visiting a counseling facility for
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1925Journal of Cancer Research and Clinical Oncology (2021) 147:1917–1925
1 3
CAM of a German comprehensive cancer center. Anticancer Res
34:943–948
Jermini M etal (2019) Complementary medicine use during cancer
treatment and potential herb-drug interactions from a cross-sec-
tional study in an academic centre. Sci Rep 9:5078. https:// doi.
org/ 10. 1038/ s41598- 019- 41532-3
Konig J, Geschwill K, Lang A, Tauchert FK, Hofheinz RD, Kripp M
(2016) Use of complementary and alternative medicine in cancer
patients: a prospective questionnaire-based study in an oncologi-
cal outpatient. Clinic Oncol Res Treat 39:260–265. https:// doi.
org/ 10. 1159/ 00044 6008
Levy AG, Scherer AM, Zikmund-Fisher BJ, Larkin K, Barnes GD,
Fagerlin A (2018) Prevalence of and factors associated with
patient nondisclosure of medically relevant information to cli-
nicians. JAMA Netw Open 1:e185293. https:// doi. org/ 10. 1001/
jaman etwor kopen. 2018. 5293
Li K, Kaaks R, Linseisen J, Rohrmann S (2010) Consistency of vitamin
and/or mineral supplement use and demographic, lifestyle and
health-status predictors: findings from the European Prospective
Investigation into Cancer and Nutrition (EPIC)-Heidelberg cohort.
Br J Nutr 104:1058–1064. https:// doi. org/ 10. 1017/ S0007 11451
00017 28
Luo Q, Asher GN (2018) Use of dietary supplements at a comprehen-
sive cancer center. J Altern Complement Med 24:981–987. https://
doi. org/ 10. 1089/ acm. 2018. 0183
Maschke J, Kruk U, Kastrati K, Kleeberg J, Buchholz D, Erickson N,
Huebner J (2017) Nutritional care of cancer patients: a survey
on patients’ needs and medical care in reality. Int J Clin Oncol
22:200–206. https:// doi. org/ 10. 1007/ s10147- 016- 1025-6
Mazzanti G, Menniti-Ippolito F, Moro PA, Cassetti F, Raschetti
R, Santuccio C, Mastrangelo S (2009) Hepatotoxicity from
green tea: a review of the literature and two unpublished cases.
Eur J Clin Pharmacol 65:331–341. https:// doi. org/ 10. 1007/
s00228- 008- 0610-7
Mazzanti G, Di Sotto A, Vitalone A (2015) Hepatotoxicity of green
tea: an update. Arch Toxicol 89:1175–1191. https:// doi. org/ 10.
1007/ s00204- 015- 1521-x
Miller PE, Vasey JJ, Short PF, Hartman TJ (2009) Dietary supple-
ment use in adult cancer survivors. Oncol Nurs Forum 36:61–68.
https:// doi. org/ 10. 1188/ 09. ONF. 61- 68
Molassiotis A etal (2005) Use of complementary and alternative medi-
cine in cancer patients: a European survey. Ann Oncol 16:655–
663. https:// doi. org/ 10. 1093/ annonc/ mdi110
Schuerger N, Klein E, Hapfelmeier A, Kiechle M, Brambs C, Paepke D
(2019) Evaluating the demand for integrative medicine practices
in breast and gynecological cancer patients. Breast Care (Basel)
14:35–40. https:// doi. org/ 10. 1159/ 00049 2235
Shalom-Sharabi I, Lavie O, Samuels N, Keinan-Boker L, Lev E, Ben-
Arye E (2017) Can complementary medicine increase adherence
to chemotherapy dosing protocol? A controlled study in an inte-
grative oncology setting. J Cancer Res Clin Oncol 143:2535–
2543. https:// doi. org/ 10. 1007/ s00432- 017- 2509-0
Wilkinson JM, Stevens MJ (2014) Use of complementary and alterna-
tive medical therapies (CAM) by patients attending a regional
comprehensive cancer care centre. J Complement Integr Med
11:139–145. https:// doi. org/ 10. 1515/ jcim- 2013- 0048
Ziemann J, Lendeckel A, Muller S, Horneber M, Ritter CA (2019)
Herb-drug interactions: a novel algorithm-assisted information
system for pharmacokinetic drug interactions with herbal supple-
ments in cancer treatment. Eur J Clin Pharmacol 75:1237–1248.
https:// doi. org/ 10. 1007/ s00228- 019- 02700-6
Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional affiliations.
Content courtesy of Springer Nature, terms of use apply. Rights reserved.

1.
2.
3.
4.
5.
6.
Terms and Conditions
Springer Nature journal content, brought to you courtesy of Springer Nature Customer Service Center GmbH (“Springer Nature”).
Springer Nature supports a reasonable amount of sharing of research papers by authors, subscribers and authorised users (“Users”), for small-
scale personal, non-commercial use provided that all copyright, trade and service marks and other proprietary notices are maintained. By
accessing, sharing, receiving or otherwise using the Springer Nature journal content you agree to these terms of use (“Terms”). For these
purposes, Springer Nature considers academic use (by researchers and students) to be non-commercial.
These Terms are supplementary and will apply in addition to any applicable website terms and conditions, a relevant site licence or a personal
subscription. These Terms will prevail over any conflict or ambiguity with regards to the relevant terms, a site licence or a personal subscription
(to the extent of the conflict or ambiguity only). For Creative Commons-licensed articles, the terms of the Creative Commons license used will
apply.
We collect and use personal data to provide access to the Springer Nature journal content. We may also use these personal data internally within
ResearchGate and Springer Nature and as agreed share it, in an anonymised way, for purposes of tracking, analysis and reporting. We will not
otherwise disclose your personal data outside the ResearchGate or the Springer Nature group of companies unless we have your permission as
detailed in the Privacy Policy.
While Users may use the Springer Nature journal content for small scale, personal non-commercial use, it is important to note that Users may
not:
use such content for the purpose of providing other users with access on a regular or large scale basis or as a means to circumvent access
control;
use such content where to do so would be considered a criminal or statutory offence in any jurisdiction, or gives rise to civil liability, or is
otherwise unlawful;
falsely or misleadingly imply or suggest endorsement, approval , sponsorship, or association unless explicitly agreed to by Springer Nature in
writing;
use bots or other automated methods to access the content or redirect messages
override any security feature or exclusionary protocol; or
share the content in order to create substitute for Springer Nature products or services or a systematic database of Springer Nature journal
content.
In line with the restriction against commercial use, Springer Nature does not permit the creation of a product or service that creates revenue,
royalties, rent or income from our content or its inclusion as part of a paid for service or for other commercial gain. Springer Nature journal
content cannot be used for inter-library loans and librarians may not upload Springer Nature journal content on a large scale into their, or any
other, institutional repository.
These terms of use are reviewed regularly and may be amended at any time. Springer Nature is not obligated to publish any information or
content on this website and may remove it or features or functionality at our sole discretion, at any time with or without notice. Springer Nature
may revoke this licence to you at any time and remove access to any copies of the Springer Nature journal content which have been saved.
To the fullest extent permitted by law, Springer Nature makes no warranties, representations or guarantees to Users, either express or implied
with respect to the Springer nature journal content and all parties disclaim and waive any implied warranties or warranties imposed by law,
including merchantability or fitness for any particular purpose.
Please note that these rights do not automatically extend to content, data or other material published by Springer Nature that may be licensed
from third parties.
If you would like to use or distribute our Springer Nature journal content to a wider audience or on a regular basis or in any other manner not
expressly permitted by these Terms, please contact Springer Nature at
onlineservice@springernature.com