Analysis and writing committee: P Appleby, V Beral, A Berrington de González, D Colin, S Franceschi, J Green, C La Vecchia, J Peto, M Plummer, G Randi, S Sweetland.
Cervical carcinoma and reproductive factors: Collaborative reanalysis of individual data on 16,563 women with cervical carcinoma and 33,542 women without cervical carcinoma from 25 epidemiological studies
Article first published online: 28 MAR 2006
Copyright © 2006 Wiley-Liss, Inc.
International Journal of Cancer
Volume 119, Issue 5, pages 1108–1124, 1 September 2006
How to Cite
International Collaboration of Epidemiological Studies of Cervical Cancer (2006), Cervical carcinoma and reproductive factors: Collaborative reanalysis of individual data on 16,563 women with cervical carcinoma and 33,542 women without cervical carcinoma from 25 epidemiological studies. Int. J. Cancer, 119: 1108–1124. doi: 10.1002/ijc.21953
- Issue published online: 5 JUN 2006
- Article first published online: 28 MAR 2006
- Manuscript Accepted: 31 JAN 2006
- Manuscript Received: 5 OCT 2005
- UNPD/UNFPA/WHO/World Bank Special Program of Research, Development, and Research Training in Human Reproduction
- Department of Reproductive Health and Research, WHO
- International Agency for Research on Cancer
- Cancer Research UK
- cervical carcinoma;
- cervical intraepithelial neoplasia;
- reproductive factors;
- full-term pregnancy;
- age at first full-term pregnancy;
- collaborative reanalysis;
- relative risk
The International Collaboration of Epidemiological Studies of Cervical Cancer has combined individual data on 11,161 women with invasive carcinoma, 5,402 women with cervical intraepithelial neoplasia (CIN)3/carcinoma in situ and 33,542 women without cervical carcinoma from 25 epidemiological studies. Relative risks (RRs) and 95% confidence intervals (CIs) of cervical carcinoma in relation to number of full-term pregnancies, and age at first full-term pregnancy, were calculated conditioning by study, age, lifetime number of sexual partners and age at first sexual intercourse. Number of full-term pregnancies was associated with a risk of invasive cervical carcinoma. After controlling for age at first full-term pregnancy, the RR for invasive cervical carcinoma among parous women was 1.76 (95% CI: 1.53–2.02) for ≥≥7 full-term pregnancies compared with 1–2. For CIN3/carcinoma in situ, no significant trend was found with increasing number of births after controlling for age at first full-term pregnancy among parous women. Early age at first full-term pregnancy was also associated with risk of both invasive cervical carcinoma and CIN3/carcinoma in situ. After controlling for number of full-term pregnancies, the RR for first full-term pregnancy at age <17 years compared with ≥≥25 years was 1.77 (95% CI: 1.42–2.23) for invasive cervical carcinoma, and 1.78 (95% CI: 1.26–2.51) for CIN3/carcinoma in situ. Results were similar in analyses restricted to high-risk human papilloma virus (HPV)-positive cases and controls. No relationship was found between cervical HPV positivity and number of full-term pregnancies, or age at first full-term pregnancy among controls. Differences in reproductive habits may have contributed to differences in cervical cancer incidence between developed and developing countries. © 2006 Wiley-Liss, Inc.