Mammography screening in Denmark

Abstract

Mammography screening is offered healthy women, and a high standard on professional and organizational level is mandatory not only in the screening programme but even in the diagnostic work-up and treatment. The main goal is to achieve a substantial reduction in disease specific mortality, but it is not possible to evaluate the effect on mortality until several years later, and continuously monitoring of the quality of all aspects of a screening programme is necessary. Based on other European guidelines, 11 quality indicators have been defined, and guidelines concerning organizational requirements for a Danish screening programme as well as recommendations for the radiographic and radiological work have been drawn up.

Full text

CLINICAL GUIDELINES DANISH MEDICAL BULLETIN
DANISH MEDICAL BULLETIN
1
This guideline has been approved by the Society of Danish Society of Radiology
(DRS); Danish Society of Breast Surgery ( DMKS), Danish society for Pathological
Anatomy and Clinical Cytology(DSPAC) 0 1.03.2011
From: Mammography Screening Progra mme, Capital Region, Section of Breast
Imaging, Copenhagen University Hospit al Rigshosptalet. Kompetencecenter Nord,
Dept Clinical Epidemiology, Aarhus University Hospital. Department of Breast
Surgery Aalborg Sygehus, Aarhus Univers ity Hospital. Department of Pathology,
Odense University Hospital. Department of Public Programs, Central Denmark
Region. Department of Radiology Ringsted Hospital., Center of Mammography
Odense University Hospital. Department of Public Health, University of Copenhagen
Correspondence: Ilse Vejborg, Diagnost ic Imaging Centre, Copenhagen Univers ity
Hospital, Copenhagen, Denmark
E-mail: ilse.vejborg@rh.regionh.dk
Dan Med Bull 2011;58(6):C4287
BACKGROUND
Mammography screening is offered asymptomatic women and
consists of a standardized breast x-ray examination at predeter-
mined intervals. At this examination, there is no patient/doctor
contact.
Screening by mammography does not reduce the risk of develop-
ing cancer, but has the potential to identify breast cancer at an
earlier stage, thereby increasing the likelihood for survival.
An overview of the Swedish Randomized studies showed a 29%
reduction in breast cancer mortality among women invited to
screening after a follow-up period of 5-13 years (1). Strongly
influenced by these results population based organized screening
by mammography started in Copenhagen in 1991, in the county
of Funen in 1993 and in 1994 in the municipality of Fredriksberg.
Together these three programs cover approximately 20% of the
Danish female population in the age group 50 – 69 years. In 2001
mammography screening was introduced on Bornholm and in
2004 in the county of West Zealand.
In 1999 a law was passed that demanded mammography screen-
ing to be offered to all Danish women in age group 50 – 69 years
but no date was set for the implementation. In a later amend
ment the implementation was set to occur no later than the end
of 2007.
Preceding this nationwide implementation was a revival of the
debate about the value of mammography screening, heavily
influenced by the report by Gøtzsche and Olsen (2,3). Interna-
tional meetings were held and papers produced focusing on this
subject. The concurrent conclusion was, that screening by mam-
mography does reduce breast cancer specific mortality
(4,5,6,7,8,9)
It has been documented, that the results from the Swedish ran-
domized studies can be reproduced in a Danish service-screening
program. Thus breast cancer specific mortality in Copenhagen fell
by 25% after 10 years of screening among those invited and by
37% among those who attended one or more times (10).
PURPOSE
The endpoint of success for a screening program is to achieve a
substantial reduction in disease specific morbidity and mortality
with as few negative side effects as possible. To reach this goal it
is necessary to build up and maintain a high standard on the
professional and organizational level not only in the screening-
program as such but even concerning the ensuing diagnostic
work-up and treatment.
In order to reduce negative side effects the screening program
must be well organized and the staff well educated. A continuous
monitoring of the quality of all aspects of the screening program
as well as derived interventions is essential to obtain and main-
tain a high standard.
The purpose of these guidelines is to support organizing and
monitoring of the regional screening programs.
INDICATORS
It is not possible to monitor the effect on breast cancer morbidity
and mortality in a population until several years after the imple-
mentation of a screening program. Therefore it is necessary to
use process indicators to monitor the screening program (11).
Appendix 1 lists quality indicators selected and defined by the
steering committee of the Danish Quality Database of Mammog-
Mammography Screening in Denmark
Clinical guidelines
Ilse Vejborg, Ellen Mikkelsen
,
Jens Peter Garne, Martin Bak
,
Anders Lernevall
,
Nikolaj Borg Mogensen
,
Walter Schwartz
&
Elsebeth
Lynge

DANISH MEDICAL BULLETIN
2
raphy Screening to monitor the Danish mammography screening
programs. These indicators were part of those used to monitor
two of the earliest Danish screening programs i.e. those in Co-
penhagen and Funen (12,13,14).
Tumor size and axillary status are two very important prognostic
factors for breast cancer survival, and characterizing a screening-
program of high quality is a high detection-rate of invasive can-
cers < 1cm and lymph node negative cancers, with as few nega-
tive side effects as possible.
To achieve the objective of screening on a population basis a high
level of attendance is essential.
To minimize worry on behalf of the screened women and to
ensure cost-effectiveness recall for further diagnostic work-up of
benign lesions not demanding any treatment per se should be
kept as low as possible.
The number of recalled women without cancer (false positives)
and the number of women with benign lesions referred to sur-
gery should be kept as low as possible with due respect to the
detection rate. Ratio between surgery for benign versus malig-
nant lesions is an indicator of the quality of the integrated diag-
nostic team consisting of specialized radiologists, surgeons and
pathologists. This has to be monitored at a local as well as at a
central level.
The number of recalls is greater among younger women and at
first screening (15).
No screening program will identify all malignant tumors at any
given time. The possibility of identifying a tumor at the time of
screening depends on several factors. Some of those factors are:
density of the breast tissue, type of cancer, growth rate of the
tumor, technical quality, skills/experience of the radiographers
and the radiologists and recall level. As an indicator of the num-
ber of over-looked, fast growing or radiologically undetectable
tumors, the number of interval cancers is used (number of inva-
sive malignant tumors diagnosed in the 2-year interval after the
women are tested negative) compared to the occurrence of
breast cancer in the background population in the absence of
screening
Screening by mammography leads to a decrease in breast cancer
mortality and also has the potential to lead to less aggressive
treatment. The number of women with invasive breast cancer
treated with breast conserving therapy increases, and the num-
ber of women needing systemic adjuvant therapy should de-
crease.
In Denmark the interval between screens for women age 50 – 69
years has been set to 24 months (+/-- 3 months), which is in ac-
cordance with the majority of other population based screening
programs. It is important for the trustworthiness of the program
to adhere firmly to this scheme. Monitoring the screening interval
is an important factor in the quality assurance of the screening
program.
Overdiagnosis defined as the identification of cancers that would
not have been found in the lifetime of the woman in the absence
of screening is a potential negative effect of a screening-program.
In order to minimize the risk of overdiagnosis and overtreatment
the relative number of DCIS cases identified in a screening pro-
gram should not exceed 20%, neither should it make up less than
10%, since it is estimated that around 30-50% of DCIS – lesions
progress to invasive cancer. Or reversely: the relative number of
invasive cancers among all screening detected malignancies
should be between 80 and 90 %. Especially the identification and
treatment of poorly differentiated DCIS lesions has a potential to
decrease mortality from breast cancer (11). To monitor overdiag-
nosis it is necessary, that the entire target-group is offered
screening within defined intervals.
A successful screening program depends on optimal diagnostic
information, which again depends on knowledgeable radiogra-
phers and technical equipment of high quality. Technical quality
control must ensure that the radiologist gets best possible diag-
nostic information with as low a radiation dose as possible. The
radiation dose should only be lowered below generally recom-
mended levels if diagnostic acuity can be maintained (11).
Most women participating in a screening program are symptom-
less. Those recalled for assessment from the screening program
therefore differ considerably from women referred due to breast
related symptoms. Recall after initial screening will in many
women cause anxiety. Therefore women with a normal or benign
test after recall must be reassured as fast as possible whereas
those with malignancy must be diagnosed and treated without
unnecessary delay. The monitoring of a screening program there-
fore must include time from screening test to information of the
result.
ORGANIZATIONAL DEMANDS
To achieve the purpose of reduction in breast cancer mortality
without significant adverse effects a screening program must
maintain high professional and organizational standards.
EUREF (The European Network of Reference Centre’s for Breast
Cancer Screening) has established a series of standards for breast
cancer screening, some valid for regional programs and some for
centers of reference (11). The following list of organizational
requirements for a Danish screening program is based partly on
these and partly on Danish Breast Cancer Cooperative Group’s
(DBCG) guidelines concerning diagnosis (16).
ORGANIZATIONAL REQUIREMENTS FOR A SCREENING PROGRAM
• Personal invitations to screening by mammography are
based on updated population data (CPR)
• Information on screening is posted with the invitation
• A questionnaire is posted with the invitation or presented at
the time of the screening. The questions must at least con-
cern previous or actual treatment with estrogen hormones,
previous operations in the breast, and whether the woman
herself has felt any lumps in the breast. The answers to these
questions are important for the evaluation of the mammo-
graphic images.
• All women in the target group 50 – 69 years are invited
biannually
• The women can at any time decline participation and even at
any time rejoin the screening program
• Each screening unit performs at least 5000 screening exami-
nations each year in a target group of 20.000 women

DANISH MEDICAL BULLETIN
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• Mammography screening is performed within an organiza-
tional framework complying with these demands and with
facilities for complete diagnostic work-up of abnormal find-
ings at the screening examination
• A steering-group is established with members from relevant
specialties and headed by a leader, which is responsible for
the program. The leader refers to the steering group
• At each screening session 2 views are taken on each breast
(cranio-caudal and mediolateral oblique)
• All participants are by letter informed of the result of the
examination
• All screening organizations have a centralized quality assur-
ance following the physical-technical recommendations in-
cluded in the European Guidelines for Quality assurance (11)
• Data are collected and used for monitoring of the program
• The leader of the program is responsible for organizing a
structure to assure that the entire target group receives invi-
tations and that a decision to recall is acted upon
• Screening images are read independently by two persons, of
which at least one is an experienced screening radiologist,
who as a minimum reads 5000 screening examinations a
year.
• All images are archived to allow comparing with consecutive
examinations and for research purposes
ORGANIZATIONAL REQUIREMENTS FOR A REFERENCE CENTER
BEYOND THE ABOVE MENTIONED
• Performs at least 10.000 screening pr year
• Provides educational programs for evaluation of perform-
ance and educational material including handling of interval
cancers
• Has a physicist as a member of the team
• Is part of an integrated team containing specially trained
radiologists, pathologists, surgeons and oncologists
• Evaluates and reports results on a regular basis
• Has epidemiological/statistical support for monitoring and
reporting
INFORMATION
Information on the screening program must be balanced, honest,
evidence-based and targeted to the different phases of the pro-
gram.
SELF-EXAMINATION
Mammography is no perfect test in the sense that a normal
screening test is no absolute guarantee that breast cancer is not
present, or that breast cancer cannot occur even in the near
future. It is therefore recommended that the letter to a partici-
pant in the screening program conveying a normal test result
includes a caution to seek medical attention, should she be aware
of anything abnormal or different in her breasts.
RADIOGRAPHER/IMAGING STAFF
The radiographers, x-ray nurses or other specially educated assis-
tants performing the actual screening mammograms often are
the only members of the team in contact with the attending
woman. To assure continuous attendance it is mandatory that
these staff members are adequately educated and behaves in a
professional way.
Complaints and praise, verbal as well as written, should be dis-
cussed at regular staff meetings.
Sensitivity as well as specificity depends on optimal positioning
and high quality of the images. It is essential that the imaging
staff is highly educated to achieve the defined standards of tech-
nical quality (11):
• More than 97% of the examinations should comply with
internationally recognized radiographic standards
• Less than 3% of attendees will need repeated examinations
for technical reasons (monitored for each imaging staff
member on a regular basis for instance every 6 months)
All attending women can expect that the member of the staff,
which they meet, is able to inform about the test itself and the
timeframe within which they can expect a letter with the result of
the test. Close to all women should be content with the screening
examination as such.
At regular intervals audit should be made over a sample of the
screening mammograms of each individual member of the
screening staff. All technical recalls should be discussed at such an
audit. The radiographers/ x-ray nurses should be fully aware of
the importance of quality control in daily work
The radiographers/ x-ray nurses should if possible take part in
consecutive diagnostic work-op, and be familiar with procedures
included in this.
The radiographers/ x-ray nurses should participate in multidisci-
plinary meetings on a regular basis, and continuous feedback
from the radiologist is essential.
THE RADIOLOGIST
The radiologist is responsible for maintaining a high image quality
and for ensuring that quality control is performed physi-
cally/technically as well as professionally.
The radiologist working with screening must be a specialist in
diagnostic radiology and must have undertaken specific education
in symptomatic as well as screening breast imaging and in the
diagnostic work-up of abnormalities detected by screening.
Even a long experience with symptomatic cases cannot replace
training in screening mammography and consecutive diagnostic
work-up (11).
DIAGNOSTIC WORK-UP
The diagnostic work-up of abnormalities detected by screening
should take place in departments fulfilling the requirements for a
diagnostic breast center, as stated below. Furthermore the de-
partment should adhere to DBCG’s guidelines for diagnosis of
breast diseases (16).
Requirements for a diagnostic breast center
• Performs at least 2000 clinical mammography examinations
per year
• Has at least one experienced radiologist evaluating at least
1000 mammography examinations pr year

DANISH MEDICAL BULLETIN
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• Has dedicated mammography equipment for diagnostic
mammography with access to equipment for magnification
exposures, with adequate conditions for reading of mammo-
graphies and with dedicated ultrasound equipment with
high-frequency transducers
• Is able to perform clinical examination, ultrasound and the
whole spectrum of relevant procedures
• Performs biopsy for cytology/histology, directed by ultra-
sound or stereotactically and by the same techniques per-
form preoperative marking of non-palpable lesions
• Work closely together with pathologists experienced in
breast cytology and histopathology
• Partakes in multidisciplinary communication and review
meetings with other team members responsible for diagno-
sis and treatment
• Partakes in monitoring of data and in analyzing feedback
The head of the screening unit is responsible for the establish-
ment of a structure ascertaining that decisions on recall are exe-
cuted. The organizations must also assure that a new letter of
invitation is sent to women not responding to the recall-letter.
Records should be kept matching those recalled to those actually
showing up.
Recall should be by letter including a telephone number for con-
tact. It is preferable not to recall by telephone as this can cause
unnecessary anxiety. For many women a recall causes distress,
and the time from receiving the recall letter to the actual exami-
nation should be as short as possible.
Letters should be posted such that they are not received in week-
end or public holidays, when contact to the screening unit is not
possible (15).
Screen detected abnormalities must be clearly marked by the
initial reader in order to clarify the reason for recall to the staff
performing the diagnostic work-up.
For educational purposes and to achieve experience it is essential
the radiologists reading the screening mammograms also take
part in the consecutive diagnostic work-up. Likewise imaging staff
from the screening unit should at times be given opportunity to
participate in the examination of recalled cases.
At the recall examination supplementary projections are made if
warranted and ultrasound examination is performed on all ab-
normal radiological findings and all palpable lesions. Biopsy
guided by ultrasound or x-ray is performed from all suspicious or
obvious malignant lesions and from all palpable solid lesions. This
also includes lesions that are considered benign based on the
imaging studies (with few exceptions listed in the DBGG guide-
lines)
TRIPLE TEST
The triple test (clinical examination, imaging and needle biopsy) is
the cornerstone of the diagnostic work-up.
The diagnostic work-up takes place within an integrated diagnos-
tic system staffed by doctors specialized in diagnosis and treat-
ment of breast cancer, i.e. a team of doctors with expert knowl-
edge in the fields of breast radiology, breast surgery and breast
pathology. Such a team works in accordance with written local
guidelines for the multidisciplinary cooperation. An essential part
of this system is that there is agreement within the team as to
who is responsible for the patient at any given time in the diag-
nostic process. For radiologically benign lesions, this will often be
the radiologist. If in such a case a needle biopsy is performed it is
the examining radiologist who is responsible for assuring concor-
dance between the radiological and pathological findings before
the diagnostic process is brought to an end.
In cases of suspected or proven malignant lesions the responsibil-
ity for the case is transferred to the breast surgeons.
The principles of the triple test (palpation, imaging and needle
biopsy) shall be pursued:
• Consensus for benign lesion: case closed and the woman
returns to the screening program
• Consensus for malignant lesion: referred to surgery
• Triple test not unequivocal: further imaging, repeated biopsy
or eventually excisional biopsy should be performed
The diagnostic process should be as short as possible to assure
that the woman can be calmed in case of benign lesions or in case
of malignancy be referred to fast one step surgery as often as
possible.
Surgery for non-symptomatic benign lesions should be avoided,
but may be necessary to achieve a definite diagnosis. The ratio
between benign and malignant lesions treated surgically is a good
indicator of how well the integrated diagnostic team works and
should be monitored locally.
MULTIDISCIPLINARY CONFERENCES
All cases where there is no consensus on the triple test and all
cases referred to surgery should be discussed within the frame-
work of the integrated diagnostic team in order to reach agree-
ment on further examination or treatment. Such a conference
should be held before the woman is informed of the results of the
examinations.
FAMILY DOCTOR
The results of the screening test should– with her consent – be
sent to the woman’s family practitioner so that he or she can be
informed on the progress of the diagnostic process and the final
result.
SCREENING OF WOMEN WITH A GENETIC DISPOSITION TO
BREAST CANCER
Women in the target population for the screening program aged
50 – 69 years with an increased risk of breast cancer determined
by their family history can be followed within the routines of the
general screening program whether they are considered to have a
moderate of high risk of breast cancer. However women with a
proven mutation in the BRCA 1/2 genes are offered more inten-
sive surveillance outside the screening program (17).

DANISH MEDICAL BULLETIN
5
SCREENING OF WOMEN PREVIOUSLY TREATED FOR BREAST CAN-
CER
Women in the target population for the screening program aged
50 – 69 years, who have been treated for breast cancer more
than 18 months ago, can be referred to the screening program
according to the recommendations in the DBCG guidelines (18)
WOMEN WITH BREAST IMPLANTS
Women with implants placed behind the pectoral muscles can
often but not always be sufficiently examined by mammography.
It is important to notify the imaging staff in such cases, as the
imaging technique may have to be changed to avoid the implants
shadowing for the glandular tissue. Women with implants be-
tween muscle and glandular tissue are normally not suited for
mammography screening.
There is no evidence for recommending screening by ultrasound.
SUMMARY
Mammography screening is offered healthy women, and a high
standard on professional and organizational level is mandatory
not only in the screening programme but even in the diagnostic
work-up and treatment. The main goal is to achieve a substantial
reduction in disease specific mortality, but it is not possible to
evaluate the effect on mortality until several years later, and
continuously monitoring of the quality of all aspects of a screen-
ing programme is necessary. Based on other European guidelines,
11 quality indicators have been defined, and guidelines concern-
ing organizational requirements for a Danish screening pro-
gramme as well as recommendations for the radiographic and
radiological work have been drawn up.
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