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Background: Smoking has been linked to mucinous ovarian cancer, but its effects on other ovarian cancer subtypes and on overall ovarian cancer risk are unclear, and the findings from most studies with relevant data are unpublished. To assess these associations, we review the published and unpublished evidence., Methods: Eligible epidemiological studies were identified by electronic searches, review articles, and discussions with colleagues. Individual participant data for 28,114 women with and 94,942 without ovarian cancer from 51 epidemiological studies were analysed centrally, yielding adjusted relative risks (RRs) of ovarian cancer in smokers compared with never smokers., Findings: After exclusion of studies with hospital controls, in which smoking could have affected recruitment, overall ovarian cancer incidence was only slightly increased in current smokers compared with women who had never smoked (RR 1·06, 95% CI 1·01-1·11, p=0·01). Of 17,641 epithelial cancers with specified histology, 2314 (13%) were mucinous, 2360 (13%) endometrioid, 969 (5%) clear-cell, and 9086 (52%) serous. Smoking-related risks varied substantially across these subtypes (p(heterogeneity)<0·0001). For mucinous cancers, incidence was increased in current versus never smokers (1·79, 95% CI 1·60-2·00, p<0·0001), but the increase was mainly in borderline malignant rather than in fully malignant tumours (2·25, 95% CI 1·91-2·65 vs 1·49, 1·28-1·73; p(heterogeneity)=0·01; almost half the mucinous tumours were only borderline malignant). Both endometrioid (0·81, 95% CI 0·72-0·92, p=0·001) and clear-cell ovarian cancer risks (0·80, 95% CI 0·65-0·97, p=0·03) were reduced in current smokers, and there was no significant association for serous ovarian cancers (0·99, 95% CI 0·93-1·06, p=0·8). These associations did not vary significantly by 13 sociodemographic and personal characteristics of women including their body-mass index, parity, and use of alcohol, oral contraceptives, and menopausal hormone therapy., Interpretation: The excess of mucinous ovarian cancers in smokers, which is mainly of tumours of borderline malignancy, is roughly counterbalanced by the deficit of endometrioid and clear-cell ovarian cancers. The substantial variation in smoking-related risks by tumour subtype is important for understanding ovarian carcinogenesis., Funding: Cancer Research UK and MRC., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Age-standardised mortality rates for breast cancer were examined for 20 countries in Europe, North America, Australia and New Zealand from 1950 to 1992 and age-birth cohort and age-period of death models were fitted to the data. Breast cancer mortality rates generally increased in the earlier decades, but more recently rates have levelled off or begun to decline in most countries. Only in 4 of the 20 countries studied, Belgium, Hungary, Poland and Spain, was there no evidence of a decline or leveling off or mortality in recent birth cohorts or in recent years. In the other countries the decline in mortality appeared to be in part due to birth cohort effects and in part due to period effects. The birth cohort effects were suggestive of a decline in breast cancer rates among women born after about 1920 and were evident in many countries especially Canada, The Netherlands, The United Kingdom and the United States. The decline in mortality in women born after 1920 appeared to be in part related to a reduction in childlessness and a reduction in age at first birth in those generations. As well as the birth cohort effects, there was some evidence of a recent overall decline in mortality rates in several countries, e.g. Austria, FRG, Greece and the UK, and this may be due to an increase in survival resulting from improved management and treatment of women with breast cancer.