Chapter 38: Penile Cancer

INCIDENCE AND ETIOLOGY

Incidence in United States

Penile cancer most commonly affects men between 50 and 70 years of age. The tumor is not unusual in younger men; in one large series, 22% of patients were younger than 40 years, and 7% were younger than 30 years (¹). In 2015, there were an estimated 1,820 new cases in the United States (²).

Epidemiology

Penile carcinoma accounts for less than 1% of all malignant neoplasms among men in the United States and Europe, but it may represent up to 20% of malignant neoplasms in men in some Asian, African, and South American countries (¹). These differences are thought to be related to the prevalence of neonatal circumcision, human papillomavirus (HPV) infection, and hygienic practices. Rates of HPV vaccination will likely become a factor in the future (³).

Incidence and Significance Worldwide

Among uncircumcised tribes of Africa and within uncircumcised Asian cultures, penile cancer may amount to 10% to 20% of all malignant neoplasms in men (¹). Carcinoma of the penis is particularly rare among the Jewish population, for whom neonatal circumcision is a universal practice (⁴). The annual number of new cases in total per year worldwide has been estimated at approximately 26,000 (⁵). Squamous cell carcinoma is the most common histologic subtype, accounting for over 95% of cases (Table 38-1) (⁶).

RISK FACTORS

Lack of Circumcision

The risk of penile cancer varies according to circumcision practice, hygienic standard, phimosis, number of sexual partners, HPV infection, exposure to tobacco products, and other factors (^1,5). Neonatal circumcision has been well established as a prophylactic measure that removes most of the risk of penile carcinoma because it eliminates the closed preputial environment where penile carcinoma most commonly develops. Phimosis is found in 25% to 75% of patients with penile carcinoma described in most large series. Reddy et al (⁷) studied the foreskins of 26 men undergoing circumcision because of phimosis and found epithelial atypia in one-third of the specimens. Data from most large series show that neonatal circumcision is protective, whereas circumcision delayed until after puberty is not (⁸).

Human Papillomavirus

Although HPV is not a reportable sexually transmitted disease, the number of new genital HPV infections has been estimated at 500,000 to 1 million annually in the United States (⁹). The terms genital condyloma, venereal warts, genital warts, and ...