Demographic and pathologic differences in the incidence of invasive penile cancer in the United States, 1995-2003.

OBJECTIVE

Penile cancer is an uncommon malignancy, so few descriptive or analytic studies have been reported in the literature. The objective of this analysis was to describe the distribution of penile cancer in the United States by demographic, pathologic, and clinical features.

METHODS

Penile cancer among 6,539 men was identified through 29 population-based registries in the United States during the period 1995-2003. These registries were estimated to represent 68% of the U.S. population. Age-adjusted incidence rates were calculated per million population using counts derived from the 2000 U.S. census. A subset of nine registries was used to examine time trends in penile cancer between 1973 and 2003.

RESULTS

Squamous cell carcinomas were the most common histologic type of penile cancer, representing 93% of all malignancies. Hispanic men had the highest age-adjusted incidence rates per million for penile cancer (6.58 per million), followed by Blacks (4.02 per million), Whites (3.90 per million), American Indians (2.81 per million), and Asian-Pacific Islanders (2.40 per million). The highest rates of penile cancer were found among Hispanic men (46.9 per million) and Black men (36.2 per million) of ages >/=85 years. Penile malignancy was rare among males under age 20 years. Time trend analysis supported a significant decrease in the incidence of penile cancer for Blacks (annual percent change, -1.9%) and Whites (annual percent change, -1.2%). The majority (61%) of penile cancers were diagnosed at a localized stage among all racial and ethnic groups, although Hispanic and Black men tended to be diagnosed at more advanced stages than Whites. No racial or ethnic differences in tumor grade were identified. The incidence of penile cancer was highest in the South (4.42 per million) and lowest in the West (3.28 per million) of the United States. The highest age-adjusted incidence rate was found among Black men in the South (4.77 per million) and the lowest rate among Asian-Pacific Islanders in the West (1.84 per million).

CONCLUSIONS

This analysis showed significant racial/ethnic and regional variation in the incidence of penile cancer. The high rate of penile cancer among Hispanic and Southern Black men suggests differences in risk factors for this malignancy, such as circumcision, hygiene, or human papillomavirus exposure.