[Show abstract][Hide abstract] ABSTRACT: Association between active smoking and risk of death among breast cancer patients reported in previous studies has been inconsistent. We investigated the association between active and passive smoking and risk of all-cause and breast cancer-specific death among female breast cancer patients in relation to menopausal and tumor estrogen/progesterone receptor (ER/PR) status. This study included 848 patients admitted to a single hospital in Japan from 1997 to 2007. Active or passive smoking status was assessed using a self-administered questionnaire. The patients were followed until December 31, 2010. We used Cox proportional-hazard model to estimate hazard ratio (HR). During a median follow-up period of 6.7 years, 170 all-cause and 132 breast cancer-specific deaths were observed. Among premenopausal patients, current smokers showed a non-significant higher risk of all-cause and breast cancer-specific death. A duration of smoking >21.5 years was positively associated with all-cause (HR = 3.09, 95% confidence interval [CI], 1.17-8.20) and breast cancer-specific death (HR = 3.35, 95% CI: 1.22-9.23, Ptrend = 0.035) among premenopausal patients. In premenopausal patients with ER+ or PR+ tumor, there was some suggestion that a longer duration of smoking was associated with higher risk of all-cause and breast cancer-specific death. Passive smoking demonstrated no significant risk. Our results suggest that a longer duration of active smoking is associated with an increased risk of all-cause and breast cancer-specific death among premenopausal patients, possibly with hormonal receptor-positive tumors. Breast cancer patients should be informed about the importance of smoking cessation. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Cancer Science 06/2015; DOI:10.1111/cas.12716 · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It has long been hypothesized that personality is associated with breast cancer risk and survival. The present population-based prospective cohort study in Japan tested this hypothesis. To investigate the association of personality with breast cancer risk, a total of 15,107 women aged 40-64 years who completed the Eysenck Personality Questionnaire-Revised (EPQ-R) Short Form were followed from 1990 to 2007. To assess the association of personality with survival after breast cancer, 250 identified cases were further followed up from the date of diagnosis to 2008, and 45 all-cause deaths were documented. Study subjects were categorized into four groups based on the quartile points of scores ranging between 0 and 12 on each EPQ-R subscale (extraversion, neuroticism, psychoticism, and lie), and the hazard ratio (HR) for each category was computed using the lowest category as reference. Multivariate analysis revealed no association between any of the four personality subscales and the risk of breast cancer. In the analysis on survival, no significant association was found between any of these subscales and the risk of death, although breast cancer cases with a higher score of extraversion tended to have a lower risk of death (P for trend = 0.07; HR for highest score level = 0.38). Exclusion of 32 cases diagnosed in the first 3 years of follow-up did not largely change the results with regard to either breast cancer risk or survival. The present findings suggest that personality does not impact significantly on the development and progression of breast cancer.
Breast Cancer Research and Treatment 04/2015; 150(3):675-84. DOI:10.1007/s10549-015-3364-9 · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The analysis of cancer trends in Japan requires periodic updating. Herein, we present a comprehensive report on the trends in cancer incidence and mortality in Japan using recent population-based data. National cancer mortality data between 1958 and 2013 were obtained from published vital statistics. Cancer incidence data between 1985 and 2010 were obtained from high-quality population-based cancer registries of three prefectures (Yamagata, Fukui and Nagasaki). Joinpoint regression analysis was performed to examine the trends in age-standardized rates of cancer incidence and mortality. All-cancer mortality decreased from the mid-1990s, with an annual percent change of -1.3% (95% confidence interval [CI]: -1.4, -1.3). During the most recent 10 years, over 60% of the decrease in cancer mortality was accounted for by a decrease in stomach and liver cancers (63% for males and 66% for females). The long-term increase in female breast cancer mortality, beginning in the 1960s, plateaued in 2008. All-cancer incidence continuously increased, with annual percent changes of 0.6% (95% CI: 0.5, 0.8) between 1985 and 2005, and 1.8% (95% CI: 0.6, 2.9) between 2005 and 2010. During the most recent 10 years, almost half of the increase in cancer incidence was accounted for by an increase in prostate cancer (60%) in males and breast cancer (46%) in females. The cancer registry quality indices also began to increase from ∼2005. Decreases in stomach and liver cancers observed for incidence and mortality reflect the reduced attribution of infection-related factors (i.e. Helicobacter pylori and hepatitis virus). However, it should be noted that cervical cancer incidence and mortality rates began to increase from ∼1990.
Japanese Journal of Clinical Oncology 03/2015; 45(4). DOI:10.1093/jjco/hyv002 · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective
This study examined the association of exposure to environmental tobacco smoke (ETS) during adulthood with stroke and its subtypes using data from a large-scale prospective cohort study in Japan.
The study population included 36,021 never-smoking Japanese women who were enrolled between 1983 and 1985 and were followed-up for 15 years. We used Cox proportional hazard regression models to estimate hazard ratios (HRs) for stroke death associated with ETS exposure at home during adulthood.
A total of 906 cases of stroke death were observed during 437,715 person-years of follow-up. Compared with never-smoking women without smoking family members, HRs for stroke mortality among never-smoking women living with smoking family members in all subjects, in those aged 40–79 years, and in those aged ≥ 80 years were 1.14 (95% confidence interval: 0.99–1.31), 1.24 (95% CI: 1.05–1.46), and 0.89 (95% CI: 0.66–1.19), respectively, after adjustment for possible confounders. The risk was most evident for subarachnoid hemorrhage [HR: 1.66 (95% CI: 1.02–2.70) in all subjects].
This study suggests that exposure to ETS at home during adulthood is associated with an increased risk of stroke among never-smoking Japanese women.
Preventive Medicine 10/2014; 67:41–45. DOI:10.1016/j.ypmed.2014.06.029 · 2.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although we usually report five-year cancer survival using population-based cancer registry data, nowadays, many cancer patients have been able to survive longer and need to be followed-up for more than five years. Long-term cancer survival figures were scarce in Japan. We reported ten-year cancer survival and conditional survival using an established statistical approach. We received data on 1,387,489 cancer cases from six prefectural population-based cancer registries in Japan, diagnosed between 1993 and 2009 and followed-up for at least five years. We estimated the ten-year relative survival of patients who were followed-up between 2002 and 2006 using period analysis. Using this ten-year survival, we also calculated the conditional five-year survival for cancer survivors who lived for some years after diagnosis. We reported ten-year survival and conditional survival of 23 types of cancer for 15-99 year-old patients and 4 types of cancer for child (0-14 years old) and adolescent and young adult (AYA, 15-29 years old) patients by sex. Variation in ten-year cancer survival by site was wide, from 5% for pancreatic cancer to 95% for female thyroid cancer. About 70-80% of child and AYA cancer patients survived for more than ten years. Conditional five-year survival for most cancer sites increased according to years, while those for liver cancer and multiple myeloma did not increase. We reported ten-year cancer survival and conditional survival using population-based cancer registries in Japan. It is important for patients and clinicians to report these relevant figures using population-based database. This article is protected by copyright. All rights reserved.
Cancer Science 09/2014; DOI:10.1111/cas.12525 · 3.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Studies on the effects of consumption of fruits, vegetables, and seaweeds on the incidence of pancreatic cancer are not conclusive. We examined the association (if any) between the consumption of fruits, vegetables, and seaweeds and the risk of pancreatic cancer in Japan. Data from 32,859 participants registered in the Ohsaki National Health Insurance Cohort Study who were 40–79 years old and free of cancer at baseline were analyzed. Consumption of fruits, vegetables, and seaweeds was assessed at baseline using a self-administered food frequency questionnaire (containing 40 items). Incidences of pancreatic cancer were identified by computer linkage with the Miyagi Prefectural Cancer Registry. During 11 years of follow-up, 137 pancreatic cancers (67 men and 70 women) were identified. The hazard ratios (95% confidence interval) of pancreatic cancer risk for the highest versus the lowest tertile were 0.82 (0.40–1.68, trend P = 0.57) in men and 0.64 (0.35–1.20, trend P = 0.22) in women for total consumption of fruits, 0.89 (0.46–1.73, trend P = 0.76) in men and 0.67 (0.33–1.35, trend P = 0.23) in women for total consumption of vegetables, and 0.92 (0.46–1.84, trend P = 0.81) in men for consumption of seaweeds (results for the consumption of seaweeds in women were not analyzed because of poor reliability), respectively. Total consumption of fruits, vegetables, and seaweeds was not associated with a reduced risk of pancreatic cancer.
[Show abstract][Hide abstract] ABSTRACT: Tobacco smoking is a major risk factor for many diseases. We sought to quantify the burden of tobacco-smoking-related deaths in Asia, in parts of which men's smoking prevalence is among the world's highest.
We performed pooled analyses of data from 1,049,929 participants in 21 cohorts in Asia to quantify the risks of total and cause-specific mortality associated with tobacco smoking using adjusted hazard ratios and their 95% confidence intervals. We then estimated smoking-related deaths among adults aged ≥45 y in 2004 in Bangladesh, India, mainland China, Japan, Republic of Korea, Singapore, and Taiwan-accounting for ∼71% of Asia's total population. An approximately 1.44-fold (95% CI = 1.37-1.51) and 1.48-fold (1.38-1.58) elevated risk of death from any cause was found in male and female ever-smokers, respectively. In 2004, active tobacco smoking accounted for approximately 15.8% (95% CI = 14.3%-17.2%) and 3.3% (2.6%-4.0%) of deaths, respectively, in men and women aged ≥45 y in the seven countries/regions combined, with a total number of estimated deaths of ∼1,575,500 (95% CI = 1,398,000-1,744,700). Among men, approximately 11.4%, 30.5%, and 19.8% of deaths due to cardiovascular diseases, cancer, and respiratory diseases, respectively, were attributable to tobacco smoking. Corresponding proportions for East Asian women were 3.7%, 4.6%, and 1.7%, respectively. The strongest association with tobacco smoking was found for lung cancer: a 3- to 4-fold elevated risk, accounting for 60.5% and 16.7% of lung cancer deaths, respectively, in Asian men and East Asian women aged ≥45 y.
Tobacco smoking is associated with a substantially elevated risk of mortality, accounting for approximately 2 million deaths in adults aged ≥45 y throughout Asia in 2004. It is likely that smoking-related deaths in Asia will continue to rise over the next few decades if no effective smoking control programs are implemented. Please see later in the article for the Editors' Summary.
PLoS Medicine 04/2014; 11(4):e1001631. DOI:10.1371/journal.pmed.1001631 · 14.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To evaluate dietary patterns in relation to colorectal cancer risk in Japanese.
We prospectively assessed the association between dietary patterns among the Japanese and the risk of colorectal cancer. Dietary information was collected from 44,097 Japanese men and women aged 40-79 years without a history of cancer at the baseline in 1994.
During 11 years of follow-up, we documented 854 cases of colorectal cancer, which included 554 cases of colon cancer and 323 cases of rectal cancer. Factor analysis (principal component analysis) based on a validated food frequency questionnaire identified three dietary patterns: (1) a Japanese dietary pattern, (2) an "animal food" dietary pattern, and (3) a high-dairy, high-fruit-and-vegetable, low-alcohol (DFA) dietary pattern. After adjustment for potential confounders, the DFA pattern was inversely associated with the risk of colorectal cancer (hazard ratio of the highest quartile vs the lowest, 0.76; 95 % confidence interval 0.60-0.97; p for trend = 0.02). When colon and rectal cancers were separated, the inverse association between the DFA pattern and cancer risk was observed for rectal cancer (p for trend = 0.003), but not for colon cancer (p for trend = 0.43). No apparent association was observed for either the Japanese dietary pattern or the "animal food" dietary pattern.
The DFA dietary pattern was found to be inversely associated with the risk of colorectal cancer. This association was observed for rectal cancer, but not for colon cancer.
Cancer Causes and Control 03/2014; 25(6). DOI:10.1007/s10552-014-0375-5 · 2.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An association of cigarette smoking with breast cancer risk has been hypothesized. However, results from previous studies have been inconsistent. This case-control study investigated the association of cigarette smoking with breast cancer risk in terms of estrogen-receptor/progesterone-receptor (ER/PgR) status. From among female patients aged 30 years and over admitted to a single hospital in Japan between 1997 and 2011, 1,263 breast cancer cases (672 ER+/PgR+, 158 ER+/PgR-, 22 ER-/PgR+, 308 ER-/PgR- and 103 missing) and 3,160 controls were selected. History of smoking (ever, never), some smoking-related measures, and passive smoking from husbands (ever, never) were assessed using a self-administered questionnaire. Polytomous logistic regression and tests for heterogeneity across ER+/PgR + and ER-/PgR- were conducted. For any hormone receptor subtype, no significant association was observed between history of smoking (ever, never) and breast cancer risk. Analysis of smoking-related measures revealed that starting to smoke at an early age of ≤19 years was significantly associated with an increased risk of postmenopausal ER-/PgR- cancer (odds ratio = 7.01, 95% confidence interval: 2.07-23.73). Other measures of smoking such as the number of cigarettes per day, the duration of smoking, and start of smoking before the first birth were not associated with breast cancer risk for any receptor subtype. There was no association between passive smoking (ever, never) and breast cancer risk for any of the four subtypes. These results indicate that history of smoking and passive smoking from husbands may have no overall effect on breast cancer risk for any hormone receptor subtype. However, it is possible that women who start to smoke as teenagers may have a higher risk of developing postmenopausal ER-/PgR- cancer. Further studies are needed to clarify the association of smoking with breast cancer risk, especially the role of starting to smoke at an early age.
[Show abstract][Hide abstract] ABSTRACT: In Japan, population-based cancer incidence data are reported several years behind the latest year of cancer mortality data. To bridge this gap, we aimed to determine a short-term projection method for cancer incidence.
Data between 1985 and 2007 were obtained from the population-based cancer registries in four prefectures (Miyagi, Yamagata, Fukui and Nagasaki). Three projection models were examined: generalized linear model with age and period (A + P linear); generalized linear model with age, period and their interactions (A*P linear); and generalized additive model with age, period and their interactions smoothed by spline (A*P spline). We performed a 5-year projection for the years 2000 and 2005, based on the data of 1985-95 and 1985-2000, respectively. Seven cancer sites (stomach, liver, colorectal, lung, female breast, cervix uteri and prostate) and all cancers combined were analyzed. The accuracy of projection was evaluated by whether each observed number fell within the 95% confidence interval of the projected number.
The A*P spline model accurately projected 8 of 13 cancer site-sex combinations, whereas the number of site-sex combinations of accurate projection was 2 and 6 for A + P linear and A*P linear models, respectively. For liver and colorectal cancers, the A*P spline model alone performed accurate projections; the relative differences between projected and observed numbers of cancer incidence ranged between -0.4 and +10.9% for the A*P spline, and between +7.4 and +37.6% for the other two models. All three models failed to project sudden increases in prostate cancer between 2000 and 2005.
The A*P spline model is a candidate method for the projection of cancer incidence in Japan. However, we need a continuous validation for prostate cancer.
Japanese Journal of Clinical Oncology 11/2013; 44(1). DOI:10.1093/jjco/hyt163 · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To evaluate the association between body mass index and mortality from overall cardiovascular disease and specific subtypes of cardiovascular disease in east and south Asians.
Pooled analyses of 20 prospective cohorts in Asia, including data from 835 082 east Asians and 289 815 south Asians. Cohorts were identified through a systematic search of the literature in early 2008, followed by a survey that was sent to each cohort to assess data availability.
General populations in east Asia (China, Taiwan, Singapore, Japan, and Korea) and south Asia (India and Bangladesh).
1 124 897 men and women (mean age 53.4 years at baseline).
Risk of death from overall cardiovascular disease, coronary heart disease, stroke, and (in east Asians only) stroke subtypes.
49 184 cardiovascular deaths (40 791 in east Asians and 8393 in south Asians) were identified during a mean follow-up of 9.7 years. East Asians with a body mass index of 25 or above had a raised risk of death from overall cardiovascular disease, compared with the reference range of body mass index (values 22.5-24.9; hazard ratio 1.09 (95% confidence interval 1.03 to 1.15), 1.27 (1.20 to 1.35), 1.59 (1.43 to 1.76), 1.74 (1.47 to 2.06), and 1.97 (1.44 to 2.71) for body mass index ranges 25.0-27.4, 27.5-29.9, 30.0-32.4, 32.5-34.9, and 35.0-50.0, respectively). This association was similar for risk of death from coronary heart disease and ischaemic stroke; for haemorrhagic stroke, the risk of death was higher at body mass index values of 27.5 and above. Elevated risk of death from cardiovascular disease was also observed at lower categories of body mass index (hazard ratio 1.19 (95% confidence interval 1.02 to 1.39) and 2.16 (1.37 to 3.40) for body mass index ranges 15.0-17.4 and <15.0, respectively), compared with the reference range. In south Asians, the association between body mass index and mortality from cardiovascular disease was less pronounced than that in east Asians. South Asians had an increased risk of death observed for coronary heart disease only in individuals with a body mass index greater than 35 (hazard ratio 1.90, 95% confidence interval 1.15 to 3.12).
Body mass index shows a U shaped association with death from overall cardiovascular disease among east Asians: increased risk of death from cardiovascular disease is observed at lower and higher ranges of body mass index. A high body mass index is a risk factor for mortality from overall cardiovascular disease and for specific diseases, including coronary heart disease, ischaemic stroke, and haemorrhagic stroke in east Asians. Higher body mass index is a weak risk factor for mortality from cardiovascular disease in south Asians.
[Show abstract][Hide abstract] ABSTRACT: Although cigarette smoking is a well-known risk factor for lung cancer, histology-specific risk has not been fully clarified in Japan. This case-control study evaluated the associations between smoking and lung cancer risk according to sex and histologic type. From among patients aged 30 yrs and over admitted to a single hospital in Japan between 1997 and 2009, 1,670 lung cancer cases and 5,855 controls were selected. History of smoking, quantity and duration of smoking, and passive smoking from spouses were assessed using a self-administered questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) for each exposure were estimated by unconditional logistic regression. Ever-smoking was significantly associated with a higher risk of squamous cell and small cell carcinoma. The OR for these two histologic types combined was larger in women (OR = 24.98, 95% CI: 13.50-46.23) than in men (OR = 9.43, 95% CI: 5.73-15.51). Analysis of the quantity and duration of smoking showed that the OR for each exposure level tended to be larger in women than in men. For adenocarcinoma, clear positive associations with quantity and duration-related factors were observed among men, and a significant positive association with passive smoking from spouses was found among non-smoking women (OR = 1.44, 95% CI: 1.06-1.95). These results suggest sex- and histologic type- differences in the association of smoking with lung cancer risk. Although smoking control should be continued to prevent lung cancers, further studies are required to better clarify differences in smoking-related lung cancer risk between the sexes and histologic types. This article is protected by copyright. All rights reserved.
Cancer Science 08/2013; 104(11):1515–1522. DOI:10.1111/cas.12273 · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
Epidemiological evidence regarding the effect of coffee on the incidence of prostate cancer is inconsistent. We aimed to investigate coffee consumption and the risk of prostate cancer risk in a general Japanese population.
We conducted a prospective cohort study in Ohsaki city, Japan, where 18 853 men aged 40–79 years participated in a baseline survey. Coffee consumption was assessed via a validated self-administered questionnaire. During 11 years of follow-up (from January 1 1995 to December 31, 2005), 318 incident cases of prostate cancer were detected. The Cox proportional hazards regression model was used to calculate the hazard ratios (HRs) and 95% confidence interval (CIs).
There was a significant inverse association between coffee consumption and the incidence risk of prostate cancer. Compared with those who did not drink coffee, the multivariate adjusted HRs were 0.81 (95% CI: 0.61–1.07), 0.73 (95% CI: 0.53–1.00), and 0.63 (095% CI: 0.39–1.00) for those who drank coffee occasionally, 1–2 cups per day, and ⩾3 cups per day, respectively, with a P for trend of 0.02.
This prospective finding from a Japanese population adds evidence that coffee intake is inversely associated with the incidence of prostate cancer.
British Journal of Cancer 05/2013; 108(11). DOI:10.1038/bjc.2013.238 · 4.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: The analysis of cancer trends in Japan has only been sporadically reported. We present a comprehensive report on the trends in cancer incidence and mortality in Japan using the most recent population-based data. METHODS: National cancer mortality data between 1958 and 2011 were obtained from published vital statistics. Cancer incidence data between 1985 and 2007 were obtained from high-quality population-based cancer registries of four prefectures (Miyagi, Yamagata, Fukui and Nagasaki). Joinpoint regression analysis was performed to examine the trends in age-standardized rates of cancer incidence and mortality. RESULTS: All-cancer mortality decreased from the mid-1990s, with an annual percent change of -1.3% (95% confidence interval: -1.4, -1.3), while all-cancer incidence continually increased from 1985, with an annual percent change of 0.7% (95% confidence interval: 0.6, 0.8). Major cancer sites, particularly the liver, colorectum and lung (males), showed a pattern of increasing incidence and mortality rates until the mid-1990s, stabilizing or decreasing thereafter. Stomach cancer showed a long-term decreasing trend for both incidence and mortality, while female breast cancer showed a continuously increasing trend. The incidence of prostate cancer, particularly at the localized stage, increased rapidly between 2000 and 2003, while that of mortality decreased from 2004. No changes were detected in the incidence or mortality for colorectal, female breast or cervical cancers after the establishment of national screening programs for these cancers. CONCLUSIONS: The analysis of cancer trends in Japan revealed a recent decrease in mortality and a continuous increase in incidence, which are considered to reflect changes in the underlying risk factors such as tobacco smoking and infection, and are partially explained by early detection and improved treatment.
Japanese Journal of Clinical Oncology 03/2013; 43(5). DOI:10.1093/jjco/hyt038 · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: PURPOSE: The associations between anthropometric factors, physical activity (PA), and breast cancer risk in terms of estrogen-receptor/progesterone-receptor (ER/PgR) status have been unclear in Japanese women. This case-control study was designed to evaluate these associations. METHODS: From among female patients aged 30 years and over admitted to a single hospital in Japan between 1997 and 2009, 1,017 breast cancer cases (538ER+/PgR+, 125ER+/PgR-, 23 ER-/PgR+, 249 ER-/PgR-, and 82 missing) and 2,902 controls were selected. Height, weight, body mass index (BMI) (kg/m(2)), and time spent exercising (hours/week) were assessed using a self-administered questionnaire. Polytomous logistic regression analysis and tests for heterogeneity across ER+/PgR+ and ER-/PgR- were conducted. RESULTS: Higher BMI was associated with a higher risk of ER+/PgR+ cancer among women overall [odds ratio (OR) = 2.41, 95 % confidence interval (CI) 1.37-4.23 for BMI ≥30.0; P trend = 0.0001] and postmenopausal women (OR = 6.24, 95 % CI 2.68-14.53 for BMI ≥30.0; P trend < 0.0001). A longer time spent exercising (more than 5 h/week) showed a decreased risk for any type of breast cancer among overall and pre- and postmenopausal women, although this did not reach statistical significance. Height was not associated with any risk. CONCLUSIONS: Higher BMI is associated with an increased risk of ER+/PgR+ cancer among women overall and postmenopausal women. PA might be associated with a decreased risk of any type. To prevent breast cancer, weight control and PA are important.
Cancer Causes and Control 03/2013; 24(5):1033-1044. DOI:10.1007/s10552-013-0181-5 · 2.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although breastfeeding is associated with a reduction in the risk for breast cancer, its relationship with another hormone-related female cancer, endometrial cancer, has not been fully investigated. The objective of the present study was to prospectively examine the association between lactation pattern and the risk for incidence of breast cancer and endometrial cancer in Japanese women. We analyzed data for 26 680 women registered in the Ohsaki National Health Insurance Cohort Study, who were 40-79 years old at the baseline. During the 11 years of follow-up, we identified 148 incident cases of breast cancer and 32 incident cases of endometrial cancer. Compared with breastfeeding only, multivariate hazard ratios and 95% confidence intervals for the risk of breast cancer incidence were 1.12 (0.92-1.37) for women who had performed mixed feeding and 1.80 (1.14-2.86) for those who fed their babies only with formula (P-trend=0.014). For endometrial cancer incidence, multivariate hazard ratios and 95% confidence intervals were 1.32 (0.86-2.03) for women who had performed mixed feeding and 3.26 (1.23-8.61) for those who had performed only formula feeding (P-trend=0.018). Our findings appear to raise the possibility that nonbreastfeeding is positively associated with the risks for both breast cancer incidence and endometrial cancer incidence. Confirmation of our findings would require further investigation.
European journal of cancer prevention: the official journal of the European Cancer Prevention Organisation (ECP) 03/2013; 22(2):187-92. DOI:10.1097/CEJ.0b013e3283564610 · 2.76 Impact Factor