Etiology of squamous cell carcinoma of the penis.

Objective: To review the epidemiology of invasive cancer of the penis based on scientific publications identified by a Medline search from 1966-2000 for the keywords penis/penile, cancer/carcinoma and risk as well as the cited references in the identified papers.

Results: Strong risk factors (OR >10) identified by case-control studies included phimosis, chronic inflammatory conditions such as balanopostitis and lichen sclerosus et atrophicus and treatment with psoralen and ultraviolet A photochemotheraphy (PUVA). A consistent association was found between penile cancer and smoking that was dose-dependent and not explained by investigated confounding factors such as sexual history. Sexual history and self-reported history of condyloma were associated with a 3-5-fold increased penile cancer risk. Cervical cancer in the wife was not consistently associated with cancer of the penis in the husband. Circumcision was associated with penile cancer risk in ecological studies. In a case-control study, circumcision neonatally, but not after the neonatal period, was associated with a 3-fold decreased risk, albeit 20% of penile cancer patients had been circumcised neonatally. In a large number of case series, human papillomavirus (HPV) DNA was identified in penile neoplastic tissue. In penile intraepithelial neoplasia, between 70 and 100% of lesions were HPV DNA positive, whereas invasive penile cancer was positive in only 40-50% of cases. A few serological case-control studies and one prospective study also identified an association between HPV type 16 and penile cancer risk. An association between penile cancer risk and HPV prevalence in the population was also suggested by ecological studies.

Conclusion: The evidence on risk factors for penile cancer suggests that preventive measures that could be considered include prevention of phimosis, treatment of chronic inflammatory conditions, limiting PUVA treatment, smoking cessation and prophylactic prevention of HPV infection.