Studies performed in the 1980s and early 1990s have shown that people who develop Kaposi sarcoma (KS) are at higher risk of developing other cancers. The demographics of those affected with human immunodeficiency virus (HIV)/AIDS and KS have changed, and individuals with HIV/AIDS and KS now live longer.Objectives
To test the hypothesis that the secondary cancers developing in patients with KS have changed in recent years and to assess the risk of secondary cancers after KS in different periods.Design, Setting, and Participants
Longitudinal data from 9 cancer registries in the Surveillance, Epidemiology, and End Results (SEER) database were used to identify cases of KS diagnosed from January 1973 to December 2013. The dates of the analysis were November 2016 to February 2017.Main Outcomes and Measures
The primary outcome was the development of secondary cancers in individuals with KS. Secondary cancers were considered only if diagnosed 2 months after a diagnosis of KS. Standardized incidence ratios (SIRs) were calculated for the development of new secondary cancers in the pre-AIDS era (1973-1979), pre–highly active antiretroviral therapy (HAART) era (1980-1995), and HAART era (1996-2013). Stratified analysis was then performed on a subset of the cases diagnosed from 1996 to 2013 based on age at diagnosis (<65 and ≥65 years), latency period between KS and the development of secondary cancers (1 year, 2-5 years, >5 to 10 years, and >10 years), and registries with higher vs lower reported rates of HIV/AIDS.Results
Among 14 905 individuals with diagnosed KS, 13 721 (92.1%) were younger than 65 years at the time of diagnosis, and 14 356 (96.3%) were male. From 1980 to 1995, SIRs were 2.01 (95% CI, 1.00-3.60) for cancer of the rectum, 49.70 (95% CI, 33.53-70.94) for cancer of the anus, 4.98 (95% CI, 2.79-8.22) for cancer of the liver, 13.70 (95% CI, 2.82-40.03) for cancer of the cervix, 6.40 (95% CI, 2.76-12.60) for Hodgkin lymphoma, and 48.97 (95% CI, 44.85-53.36) for non-Hodgkin lymphoma. From 1996 to 2013, cancer of the anus, Hodgkin lymphoma, non-Hodgkin lymphoma, and cancer of the liver remained associated with KS, with the addition of the following significant SIRs: 6.99 (95% CI, 3.20-13.27) for cancer of the tongue, 10.28 (95% CI, 1.24-37.13) for cancer of the penis, and 17.62 (95% CI, 3.63-51.49) for acute lymphocytic leukemia. The SIR of developing any tumor after KS decreased significantly from 3.36 to 1.94 from the pre-HAART era to the HAART era.Conclusions and Relevance
There has been a significant decline in the overall risk of secondary cancers after KS. Certain cancers, including acute lymphocytic leukemia, cancer of the tongue, and cancer of the penis, are increasingly becoming more common in the HAART era compared with the pre-HAART era. Close monitoring and screening for these secondary cancers is desirable in patients with KS.