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 We bring together the epidemiological evidence, published and unpublished, on these associations, and review the relevant randomised evidence.MethodsPrincipal analyses used individual participant data from all eligible prospective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.

The findings on DSH are probably explicable by confounding variables, such as adverse social factors, associated both with the request for termination and with subsequent self-harm. No overall increase in reported psychiatric morbidity was found.

Objective To describe the long term effects of the use of oral contraceptives on mortality. Design Cohort study with 25 year follow up. Details of oral contraceptive use and of morbidity and mortality were reported six monthly by general practitioners. 75% of the original cohort was "flagged" on the NHS central registers. Setting 1400 general practices throughout Britain. Subjects 46 000 women, half of whom were using oral contraceptives at recruitment in 1968-9. Median age at end of follow up was 49 years. Main outcome measures Relative risks of death adjusted for age, parity, social class, and smoking. Results Over the 25 year follow up 1599 deaths were reported. Over the entire period of follow up the risk of death from all causes was similar in ever users and never users of oral contraceptives (relative risk = 1.0, 95% confidence interval 0.9 to 1.1; P = 0.7) and the risk of death for most specific causes did not differ significantly in the two groups. However, among current and recent (within 10 years) users the relative risk of death from ovarian cancer was 0.2 (0.1 to 0.8; P = 0.01), from cervical cancer 2.5 (1.1 to 6.1; P = 0.04), and from cerebrovascular disease 1.9 (1.2 to 3.1, P = 0.009). By contrast, for women who had stopped use >10 years previously there were no significant excesses or deficits either overall or for any specific cause of death. Conclusion Oral contraceptives seem to have their main effect on mortality while they are being used and in the 10 years after use ceases. Ten or more years after use ceases mortality in past users is similar to that in never users.

Background and Purpose A nested case-control analysis of data collected during the prospective Royal College of General Practitioners' Oral Contraception Study was performed to examine the relation between use of oral contraception and risk of stroke.Methods The 253 women who had a first-ever stroke (International Classification of Diseases, eighth revision, codes 4300 to 4389) or amaurosis fugax (code 3791) between 1968 and 1990 (case subjects) were compared with 759 women who did not have this diagnosis (control subjects).Results Smoking, social class, and history of hypertension were found to be important risk factors for stroke. Women who had ever used oral contraceptives had an increased risk of all stroke (odds ratio, 1.5; 95% confidence interval, 1.1 to 2.0,