SummaryBackgroundMenarche and menopause mark the onset and cessation, respectively, of ovarian activity associated with reproduction, and affect breast cancer risk. Our aim was to assess the strengths of their effects and determine whether they depend on characteristics of the tumours or the affected women.MethodsIndividual data from 117 epidemiological studies, including 118 964 women with invasive breast cancer and 306 091 without the disease, none of whom had used menopausal hormone therapy, were included in the analyses. We calculated adjusted relative risks (RRs) associated with menarche and menopause for breast cancer overall, and by tumour histology and by oestrogen receptor expression.FindingsBreast cancer risk increased by a factor of 1·050 (95% CI 1·044–1·057; p<0·0001) for every year younger at menarche, and independently by a smaller amount (1·029, 1·025–1·032; p<0·0001), for every year older at menopause. Premenopausal women had a greater risk of breast cancer than postmenopausal women of an identical age (RR at age 45–54 years 1·43, 1·33–1·52, p<0·001). All three of these associations were attenuated by increasing adiposity among postmenopausal women, but did not vary materially by women's year of birth, ethnic origin, childbearing history, smoking, alcohol consumption, or hormonal contraceptive use. All three associations were stronger for lobular than for ductal tumours (p<0·006 for each comparison). The effect of menopause in women of an identical age and trends by age at menopause were stronger for oestrogen receptor-positive disease than for oestrogen receptor-negative disease (p<0·01 for both comparisons).InterpretationThe effects of menarche and menopause on breast cancer risk might not be acting merely by lengthening women's total number of reproductive years. Endogenous ovarian hormones are more relevant for oestrogen receptor-positive disease than for oestrogen receptor-negative disease and for lobular than for ductal tumours.FundingCancer Research UK.

SummaryBackgroundPublished findings on breast cancer risk associated with different types of menopausal hormone therapy (MHT) are inconsistent, with limited information on long-term effects. We bring together the epidemiological evidence, published and unpublished, on these associations, and review the relevant randomised evidence.MethodsPrincipal analyses used individual participant data from all eligible prospective studies that had sought information on the type and timing of MHT use; the main analyses are of individuals with complete information on this. Studies were identified by searching many formal and informal sources regularly from Jan 1, 1992, to Jan 1, 2018. Current users were included up to 5 years (mean 1·4 years) after last-reported MHT use. Logistic regression yielded adjusted risk ratios (RRs) comparing particular groups of MHT users versus never users.FindingsDuring prospective follow-up, 108 647 postmenopausal women developed breast cancer at mean age 65 years (SD 7); 55 575 (51%) had used MHT. Among women with complete information, mean MHT duration was 10 years (SD 6) in current users and 7 years (SD 6) in past users, and mean age was 50 years (SD 5) at menopause and 50 years (SD 6) at starting MHT. Every MHT type, except vaginal oestrogens, was associated with excess breast cancer risks, which increased steadily with duration of use and were greater for oestrogen-progestagen than oestrogen-only preparations. Among current users, these excess risks were definite even during years 1–4 (oestrogen-progestagen RR 1·60, 95% CI 1·52–1·69; oestrogen-only RR 1·17, 1·10–1·26), and were twice as great during years 5–14 (oestrogen-progestagen RR 2·08, 2·02–2·15; oestrogen-only RR 1·33, 1·28–1·37). The oestrogen-progestagen risks during years 5–14 were greater with daily than with less frequent progestagen use (RR 2·30, 2·21–2·40 vs 1·93, 1·84–2·01; heterogeneity p<0·0001). For a given preparation, the RRs during years 5–14 of current use were much greater for oestrogen-receptor-positive tumours than for oestrogen-receptor-negative tumours, were similar for women starting MHT at ages 40–44, 45–49, 50–54, and 55–59 years, and were attenuated by starting after age 60 years or by adiposity (with little risk from oestrogen-only MHT in women who were obese). After ceasing MHT, some excess risk persisted for more than 10 years; its magnitude depended on the duration of previous use, with little excess following less than 1 year of MHT use.InterpretationIf these associations are largely causal, then for women of average weight in developed countries, 5 years of MHT, starting at age 50 years, would increase breast cancer incidence at ages 50–69 years by about one in every 50 users of oestrogen plus daily progestagen preparations; one in every 70 users of oestrogen plus intermittent progestagen preparations; and one in every 200 users of oestrogen-only preparations. The corresponding excesses from 10 years of MHT would be about twice as great.FundingCancer Research UK and the Medical Research Council.

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58 515 women with invasive breast cancer and 95 067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19 -1.45, P50.00001) for an intake of 35 -44 g per day alcohol, and 1.46 (1.33 -1.61, P50.00001) for 545 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5 -8.7%; P50.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P50.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98 -1.07, and for current smokers=0.99, 0.92 -1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver. Many epidemiological studies have investigated the relationship between breast cancer and the consumption of alcohol and/or tobacco. References to over 80 studies that have collected relevant data, as well as to reviews of the subject, are given in Appendix II (www. bjcancer.com). The published results from these studies have general...

It is well known that the leading causes of death are now chronic diseases such as cancer, cerebrovascular problems and heart disease in developed countries, including Japan. 1 They are related to daily lifestyle, including dietary habit, alcohol drinking, smoking, physical exercise, and factors for stress. Because dietary habit, in particular, appears to play a major role in their pathogenesis, batteries of tests to assess intake of foods/nutrients, including fats/fatty acids, antioxidants and dietary fibers, are needed for epidemiologic studies.There are several tools available, including diet records (DRs)/weighed diet records (WDRs), 24-hour recall, food frequency questionnaires (FFQs), and duplicate methods. Calculation of intake of nutrientsWe computed the average daily consumption of energy and selected nutrients using information from the FFQ and lifestyle questionnaire, including consumption of alcohol. According to the regression analysis, selected nutrients were adopted as dependent parameters and foods/food groups consumed, intake frequency, portion size (in grams) from our database, 5,8 or typical/standard values from the literature, nutrient contents per 100 grams of foods/food groups listed in the respective composition tables or of the model recipes were assumed to be independent variables. [9][10][11][12][13] With the WDRs, we calculated mean daily intakes of selected nutrients by multiplying the consumption of foods/food groups (in grams) and nutrient contents per 100 grams of foods as listed in the composition tables or model recipes. ValidationFirst, we compared mean daily intakes of energy and 26 selected nutrients gauged with the FFQ against those with the 3d-WDRs. Differences in means and ratios were computed with the FFQ vs. 3d-WDRs values, and examined by t-test using Excel ® and the SPSS ® -10.0 software package.Second, we calculated crude Pearson's correlation coefficients (CCs), log-transformed Pearson's CCs, log-transformed and energy-adjusted Pearson's CCs, and de-attenuated, log-transformed and energy-adjusted Pearson's CCs between intakes of selected nutrients based on the FFQ and 3d-WDRs. Energy adjustment was executed using regression models. 14 De-attenuated Pearson's CCs were computed by partitioning within-and inter-individual variations by one way of analysis of variance according to the formula described elsewhere. 3, 15-17 Crude Spearman's rank CCs and energy-adjusted Spearman's rank CCs were also calculated. 18,19 Statistical significance was verified with the 95% confidence interval.Third, after categorizing daily intakes of nutrients quantified with the FFQ and 3d-WDRs into quartiles, we computed percentages of exact agreement, agreement within adjacent categories, and disagreement. Ethical issuesOur study protocol was reviewed and approved by the Internal Review Board at Nagoya City University Graduate School of Medical Sciences. Written informed consent was obtained from each participant. Profile of study subjectsThe mean ages standard deviations (SDs) (minimum -max...

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