The pattern of secondary cancers in patients with Kaposi sarcoma in the United States.

PURPOSE

In the U.S., Kaposi sarcoma (KS) occurs mostly in HIV-infected patients, who are also at increased risk of developing secondary cancers. The trends in secondary cancer risk are unclear in the HAART era.

METHODS

We extracted data from the SEER database on patients diagnosed with KS between 1981 and 2013, stratified into the pre-HAART (1981-1995) and HAART (1996-2013) eras. We compared the risk of secondary cancer in KS patients and the general population, and estimated the absolute risk.

RESULTS

We followed 13,535 KS patients for 49,813 person-years, during which 1,041 secondary cancers were diagnosed: 774 in the pre-HAART and 267 in the HAART era. In the pre-HAART era, non-Hodgkin's lymphoma (NHL) and anal carcinomas were the most common secondary cancers. The standard incidence ratio of secondary cancers decreased from 3.44 (pre-HAART era) to 1.94 (HAART era) in patients aged <70 years. The absolute excess risk decreased from 178 to 68 cases per 10,000 person-years. The risk of NHL decreased, while the risk of anal carcinoma did not change significantly. The risk of lung cancer was lower in KS patients than in the general population. The absolute risk of non-AIDS-defining cancers increased fourfold in the HAART era.

CONCLUSIONS

The absolute risk of non-AIDS-defining secondary cancers has increased in KS patients in the HAART era. However, the overall relative risk of secondary cancers has decreased, mainly due to a significant decrease in the risk of NHL.