Heterogeneous Etiology of Squamous Carcinoma of the Vulva

OBJECTIVE: To correlate various previously identified risk factors, different histologic types, and the presence of human papillomaviruses (HPV) in squamous vulvar carcinomas and intraepithelial precursor lesions. METHODS: Cases of squamous vulvar carcinomas and intraepithelial precursor lesions from a case-control study were analyzed by histologic type, the presence of HPV, and HPV type. These findings were correlated with demographic and interview data. RESULTS: Significant differences (P < .001) in the prevalence of HPV DNA were noted between the following: 1) patients with high-grade vulvar intraepithelial neoplasia (VIN) (48 of 54 88.9%), 2) different types of squamous carcinomas, designated basaloid and warty carcinomas (18 of 21 85.7%), and 3) keratinizing squamous carcinoma (three of 48 6.3%). When the risk factor profiles for basaloid or warty carcinoma and keratinizing squamous carcinoma were compared, it was found that basaloid and warty carcinoma was significantly associated with the classical cervical cancer risk factors (lifetime number of sexual partners, age at first intercourse, abnormal Papanicolaou smears, venereal warts, low socioeconomic status, and cigarette smoking) whereas keratinizing squamous carcinoma was less strongly linked to these factors and in some cases not at all. The risk profile for VIN was similar to that of basaloid and warty carcinoma (with respect to sexual and reproductive history and smoking), although effects were weaker for some factors. CONCLUSION: The results of this study further support the view that vulvar carcinoma has two different etiologies, one related to HPV infection and one that is not.