The hormonal background of endometrial cancer is insufficiently characterised. We investigated the significance of parity, age at first birth, intensity between births, length of time from the first to the last birth and length of delivery-free premenopausal period in a cohort of grand multiparous (GM) women, i.e., women with at least 5 births. Data of the Population Register of Finland (86,978 GM-women) and the population-based Finnish Cancer Registry were combined. Standardised incidence ratios (SIRs) were calculated by dividing the number of observed cancer cases by the expected number based on the national incidence rates. Key words: endometrial cancer; age at first birth; parity; grand multiparity; birth periodEndometrial cancer is a hormone-dependent malignancy. Unopposed estrogen promotes malignant transformation of the endometrium, an action that is counteracted by progesterone. 1 Pregnancy is characterised by continuous progesterone production from the early weeks of gestation until delivery. 2 Possibly for this reason, at least partly, parous women have a markedly lower risk of endometrial cancer than nulliparous women. [3][4][5][6][7][8] The term grand multiparity (GM) defines women who have undergone at least 5 full-term pregnancies. 9 The Population Register of Finland contains detailed information on the births and children of all GM mothers. Using this national population register of GM-women and data of Finnish Cancer Registry, we studied the significance of parity, age at first birth, average intensity between births, birth period and premenopausal delivery-free period as risk determinants of endometrial cancer. MATERIAL AND METHODS Population-based registersThe computerised files of the Finnish Population Register, which includes links between parents and their children who were living at the same address in 1974 or later, revealed 86,978 GMwomen during the period 1974 until the end of 1997. Follow-up for endometrial cancer was done automatically through the files of the national, population-based Finnish Cancer Registry with personal identifiers. Follow-up for cancer started on 1 January 1974 or at the birth of the fifth child, whichever was later, and ended at death, emigration or on 31 December 1997, whichever was first. There were 1.68 million person-years in the study. The mean length of follow-up was 19.3 years.The cancer registry data also included information about the histopathologic diagnosis made by local pathologists and clinical stage at diagnosis. Statistical methodsCases of endometrial cancer and person-years at risk were counted by 5-year age groups and separately for 4 parity categories (5, 6, 7 and 8ϩ children), 4 categories by age at first birth (Ͻ20, 20 -24, 25-29 and 30ϩ years) and 3 birth-intensity categories (average interval between the first 5 deliveries Ͻ2.0, 2.0 -3.0 and Ͼ3.0 years). Age at follow up of cancer was categorised into 3 groups, Ͻ50 years ("premenopausal" women), 50 -64 years ("postmenopausal" women) and 65ϩ years. For women 50 years or older, most of who...

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Knowledge is limited on mortality of grand multiparous women (> or =5 deliveries), whose hormonal, metabolic, and social conditions differ from the average. The authors studied overall and cause-specific mortality in 1974-2001 among 87,922 grand multiparous women including 3,678 grand grand multiparous women (> or =10 deliveries) in Finland. Standardized mortality ratios were defined as ratios of observed to expected numbers of deaths, both derived from national cause-of-death files. During follow-up, 18,870 grand multiparous women and 625 grand grand multiparous women died (standardized mortality ratios (SMRs) = 0.95 and 1.01, respectively). Decreased mortality among grand multiparous women was found for cancers of the breast (SMR = 0.64, 95% confidence interval (CI): 0.59, 0.69), corpus uteri (SMR = 0.68, 95% CI: 0.56, 0.80), ovary (SMR = 0.68, 95% CI: 0.60, 0.75), bladder (SMR = 0.59, 95% CI: 0.41, 0.82), and respiratory tract (SMR = 0.80, 95% CI: 0.72, 0.88). The only malignant tumor associated with elevated mortality was kidney cancer (SMR = 1.38, 95% CI: 1.21, 1.56). The standardized mortality ratio was also low for dementia (SMR = 0.78, 95% CI: 0.72, 0.84), respiratory diseases (SMR = 0.80, 95% CI: 0.75, 0.85), and accidents and violent causes (SMR = 0.79, 95% CI: 0.73, 0.84). Mortality from diabetes mellitus (SMR = 1.42, 95% CI: 1.29, 1.55) and ischemic heart disease (SMR = 1.10, 95% CI: 1.08, 1.13) was increased. According to this study, overall mortality among grand multiparous women is not elevated. Low mortality from cancers is offset by higher mortality from cardiovascular conditions and diabetes mellitus.

Previous studies suggest that high parity increases the risk of cervical cancer. We studied the risk of cervical cancer (CC) and cervical intraepithelial neoplasia (CIN3) in a Finnish cohort of grand multiparous (GM) women (at least five children) with low prevalence of sexually transmitted infections (STI). The Finnish Cancer Registry data revealed 220 CC and 178 CIN3 cases among 86 978 GM women. Standardised incidence ratios (SIR) were calculated from the numbers of observed and expected cases. Interval analyses by parity, age at first birth and average birth interval were done using multivariate Poisson regression. Seroprevalence of human papillomavirus (HPV) 16 and Chlamydia trachomatis was tested among 561 GM women and 5703 women with 2 -4 pregnancies. The incidence among GM women was slightly above the national average for squamous cell carcinoma of cervix uteri (SIR 1.21, 95% CI 1.05 -1.40) and CIN3 (1.37, 95% CI 1.17 -1.58), but lower for adenocarcinoma (SIR 0.77, 95% CI 0.52 -1.10). The seroprevalence of HPV16 and Chlamydia trachomatis among GM women was lower than in the reference population, except among those women who had their child under age 19. Age under 20 years at first birth increased the risk of CC and CIN3 especially in premenopausal GM women, while increasing parity had no effect. The small relative risks of CC and CIN3 among GM women in our study as compared to studies from other countries can be explained by the exceptionally low prevalence of STIs in Finnish GM women. The observed SIRs between 1.2 and 1.4 should be interpreted to represent increased risk attributable to grand multiparity. The increased incidence of CC and CIN3 among young GM women suggests causal association to HPV 16 and Chlamydia trachomatis infections.

BackgroundOvarian cancer is one of the most lethal cancers and women with type 2 diabetes (T2D) have even poorer survival from it. We assessed the prognosis of ovarian cancer in women with type 2 diabetes treated with metformin, other forms of antidiabetic medication, or statins.MethodsStudy cohort consisted of women with T2D diagnosed with ovarian cancer in Finland 1998–2011. They were identified from a nationwide diabetes database (FinDM), being linked to several national registers. Patients were grouped according to their medication in the three years preceding ovarian cancer diagnosis. The Aalen–Johansen estimator was used to describe cumulative mortality from ovarian cancer and from other causes in different medication groups. Mortality rates were analysed by Cox models, and adjusted hazard ratios (HR) with 95% confidence intervals (95% CIs) were estimated in relation to the use of different forms of medication. Main outcome measures were death from ovarian cancer and death from other causes.ResultsDuring the accrual period 421 newly diagnosed ovarian cancers were identified in the FinDM database. No evidence was found for any differences in mortality from ovarian cancer or other causes between different antidiabetic medication groups. Pre-diagnostic use of statins was observed to be associated with decreased mortality from ovarian cancer compared with no such use (HR 0.72, 95% CI 0.56–0.93).ConclusionsOur findings are inconclusive as regards the association between metformin and ovarian cancer survival. However, some evidence was found for improved prognosis of ovarian cancer with pre-diagnostic statin use, requiring cautious interpretation, though.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4676-z) contains supplementary material, which is available to authorized users.