Cancer incidence among Finnish women with surgical treatment for cervical intraepithelial neoplasia, 1987-2006.

A cohort of 26,876 women with surgical treatment for cervical intraepithelial neoplasia (CIN) during 1986-2004 was identified from the national Hospital Discharge Register. This cohort was followed up until December 31, 2006 (mean 8.4 years) through the Finnish Cancer Registry for cancer incidence during 1987-2006. There were 572 cases of cancer which is slightly more than would be expected on the basis of the national average cancer incidence in Finland. The standardized incidence ratio (SIR) was 1.14 and 95% confidence interval (CI) was 1.05-1.24. There was a statistically significant excess of cancers of the vulva (SIR: 6.15, 95% CI: 3.18-10.7), vagina (SIR: 9.08, 95% CI: 2.95-21.2), cervical cancer (SIR: 1.69, 95% CI: 1.07-2.53) and precancerous high-grade lesion of the uterine cervix (SIR: 1.29, 95% CI: 1.10-1.50). The SIR for smoking-related cancers combined, excluding cervical cancer, was 1.45 (95% CI: 1.12-1.86). The differences in cancer risk between treatment modalities were minor. Delivery after the CIN surgery did not decrease the overall cancer risk. In conclusion, women previously treated for CIN have an increased long-term risk of cancers related to human papillomavirus (HPV) and smoking.