Penile Kaposis sarcoma in the state of California

Penile Kaposi's sarcoma (PKS) is a rare and poorly characterized disease. Kaposi's sarcoma is common in HIV disease and is an AIDS-defining illness. This study aimed to review epidemiologic characteristics and changes in the incidence of PKS using a total population-based database.

Data from the California Cancer Registry (CCR) were reviewed for the years 1988-2004, identifying all cases of penile cancer. Tumors were classified by histology and stage. Annual age-adjusted incidence and actuarial survival rates were calculated for the overall population and subdivided histology.

From 1988-2004, 2870 cases of penile cancer were identified. Squamous cell carcinoma accounted for 87% of all penile cancer (n = 2507), and PKS was the second most common, accounting for 4.6% (n = 132). Patients diagnosed with PKS demonstrated a significantly lower mean age (years) than the overall cohort (43.7 versus 62.6, p < .0001). The incidence of PKS peaked in 1992 with a subsequent dramatic decline, the same year as incident AIDS cases. The percentage of all penile cancer comprised by PKS dropped from 7.4% in the 1988-1995 cohort to 1.7% in the 1995-2004 cohort (p < 0.0001). Patients diagnosed with PKS demonstrated a significantly lower 5 (32.8% versus 76.6%, p < .0001) and 10 year (29.5% versus 69.6%, p < .0001) relative overall survival than those with squamous cell carcinoma.

PKS is the second most frequent malignancy of the penis, occurring at a younger age and portending a worse prognosis than other forms of penile cancer. The proportion of PKS tumors has declined in recent years, reflecting improvements in HIV treatment that occurred during the study period.