Risk of endometrial, ovarian, vulvar, and vaginal cancers after a positive cervical cytology followed by negative histology.

OBJECTIVE

To estimate the subsequent incidence of cancers of endometrium, ovary, vulva, and vagina among women with positive cytology at screening for cervical cancer followed by negative histology.

METHODS

This was a longitudinal cohort study involving women attending the organized mass screening in Finland from 1971-1990 with class II, III, IV, or V cytology followed by negative histologic confirmation, and a sample of 42,844 women attending the organized mass screening in Finland in 1971-1976 with cytologic class I smears without any gynecologic symptoms or infections. Follow-up on the women to the end of 1994 for subsequent cancers was maintained by linkage to the national cancer registry. Standardized incidence ratios with 95% confidence intervals (CI), with rates for all of Finland as reference, were estimated.

RESULTS

The standardized incidence ratios after negative class I smears of all the cancers studied were between 0.9 and 1.0. Ovarian cancer was not associated with positive cervical cytology. After positive class III-V cytology, the standardized incidence ratio of endometrial carcinoma was 1.6 (CI 1.0, 2.2) and that of vulvar carcinoma was 5.8 (CI 2.3, 12). The standardized incidence ratios of vaginal cancer after class II and III-V cytological smear were 2.7 (CI 1.7, 4.1) and 16.4 (CI 7.1, 32), respectively. The relative risks of all the cancers studied were greatest during the first year of follow-up and persisted for more than 5 years for vulvar and vaginal cancers.

CONCLUSION

Although the Papanicolaou smear is poor in detecting cancers other than cervical, in clinical practice, the possibility of other gynecologic cancer has to be considered in surveillance after positive cervical cytology is followed by negative histology.