Determinants of invasive vulvar cancer risk: an Italian case-control study.

Risk factors for vulvar cancer have been evaluated in a case-control study conducted between 1987 and 1990 in northern Italy on 73 women with histologically confirmed invasive vulvar cancer and 572 control subjects in hospital for acute nongynecological, nonneoplastic non-hormone-related conditions. The risk of vulvar cancer was inversely related to education level: with reference to women reporting less than 7 years of schooling, the relative risk estimates were 0.6 and 0.4, respectively, in those reporting 7 to 11 and 12 or more years of schooling (chi 2(1) trend = 4.91 P = 0.03). No relationship emerged between number of births and spontaneous or induced abortions. Parous women reporting late first birth tended to be at lower risk (relative risk = 0.5, 95% confidence interval 0.3 to 1.1 for < 25 vs > or = 25 years at first birth), but there was no evidence of the risk to decrease with increasing age at first birth. The risk of vulvar cancer increased with body mass index, but the trend in risk was not significant after taking into account potential confounders in the multivariate analysis. No association emerged with indicators of sexual habits, menstrual history, and smoking. The risk of the disease was lower in women reporting Pap smears during their life and diminished with increasing number of cervical smears and decreasing recency of last Pap: compared to women reporting no Pap screening, it was 0.5 in those who reported one smear and 0.3 in those with two or more.