Second primary cancers following anal and cervical carcinoma: evidence of shared etiologic factors.

The authors examined the incidence of second primary cancers occurring after cervical and anal cancer. Data from the Connecticut Tumor Registry for 1935-1988 and eight other US tumor registries for 1973-1988 were used. Women with primary invasive cervical cancer had a relative risk of 4.6 (95% confidence interval (CI) 2.4-8.1) for subsequent invasive anal cancer. Increased relative risks after cervical cancer were also found for cancers of the oral cavity (relative risk (RR) = 2.2), stomach (RR = 1.5), rectum (RR = 1.4), larynx (RR = 3.4), lung (RR = 3.0), vagina (RR = 5.6), bladder (RR = 2.7), for kidney (RR = 1.9); decreased relative risks were noted for melanoma (RR = 0.5) and breast cancer (RR = 0.8). Patients with a primary diagnosis of anal cancer had relative risks for subsequent invasive and in situ cervical cancer of 1.3 (95% CI 0.2-4.5) and 3.4 (95% CI 0.9-8.8), respectively. Anal cancer was also associated with increased relative risks of subsequent lung (RR = 2.5) and prostate (RR = 1.8) cancers, whereas the relative risk of uterine cancer was 0.2 (95% CI 0.0-0.9). These findings support other evidence for common factors, such as human papillomavirus infection and cigarette smoking, in the etiology of cervical and anal cancer.