Cancer risk in women with 10 or more deliveries.
OBJECTIVE
To determine cancer incidence among Finnish women with 10 or more deliveries.


METHODS
Finnish women with at least 10 childbirths before December 31, 2010 (n=4,967) were identified from the Finnish Population Register and followed for cancer incidence through the Finnish Cancer Registry to the end of 2010. Cancer risks in this cohort were expressed as ratios between observed and expected numbers of cases (standardized incidence ratios), both drawn from the Finnish Cancer Registry, with 95% confidence intervals (CIs).


RESULTS
Total cancer incidence was markedly lower than in the reference population (656 cases, standardized incidence ratio 0.76, 95% CI 0.73-0.79). There was clearly less breast (0.44, 0.35-0.53), ovarian (0.49, 0.28-0.80), endometrial (0.31, 0.17-0.44), and basal cell skin cancer (0.72, 0.60-0.85) than in the reference population. The incidence of thyroid cancer (2.33, 1.59-3.29), lip cancer (2.87, 1.05-6.24), and uterine sarcoma (3.41, 1.47-6.72) was markedly increased.


CONCLUSIONS
Women with 10 or more deliveries show a decreased overall cancer incidence as a result of decreased risks of cancers of the ovary, endometrium, and breast and basal cell carcinoma of the skin. The increased risks were observed in thyroid cancer and some rare cancer types.
Department of Obstetrics and Gynecology, University of Helsinki and Helsinki University Central Hospital, and the Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, the Department of Obstetrics and Gynecology, Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, and the School of Health Sciences, University of Tampere, Tampere, Finland.
Emma
E
Högnäs
Antti
A
Kauppila
Eero
E
Pukkala
Juha S
JS
Tapanainen
D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology; D002280:Basal Cell Carcinoma / Q000453:epidemiology; D016889:Endometrial Neoplasms / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D009369:Neoplasms / Q000453:epidemiology*; D010051:Ovarian Neoplasms / Q000453:epidemiology; D010298:Parity / Q000502:physiology; D011247:Pregnancy; D012042:Registries; D012307:Risk Factors; D012878:Skin Neoplasms / Q000453:epidemiology; D013964:Thyroid Neoplasms / Q000453:epidemiology; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology