Introduction We described Kaposi sarcoma (KS) incidence changes during the AIDS emergence and subsequently in Zimbabwe with a high prevalence of HIV infection and Uganda with an intermediate HIV/AIDS prevalence and known to have high rates of endemic KS.

Methods Cancer data were extracted from the cancer registries of Harare (1990–2005), Bulawayo (1963–1972), Zimbabwe and Kyadondo, Uganda (1960–1971 and 1991–2007). We used a join point model to analyse the time trends of age-standardised rates, and the populations were compared by computing the standardised incidence ratio and 95% CIs.

Results In both countries, an increase in the incidence of KS accompanied the AIDS emergence. In Harare, KS incidence seemed to change according to the time trend of HIV/AIDS prevalence; however, in Kyadondo, we observed an increase of KS incidence in people over 50 years despite the decrease in HIV prevalence. Before the AIDS epidemic, KS incidence in Bulawayo was similar to that in Kyadondo in both genders; however, in men it became higher in Harare than Kyadondo during the AIDS epidemic, thus seeming to follow the geographical distribution of HIV prevalence. In women, the geographical pattern of KS appeared independent of HIV prevalence. In the populations studied, despite HIV prevalence being higher in females than males, KS incidence was higher in males than females.

Conclusion HIV prevalence could have different impacts on KS incidence, possibly explained by other risk factor exposures. Furthermore, a higher risk of KS emergence in men or increased risk factor exposure in men could explain the gender differences.