Relapse patterns among children and adolescents with Kaposi sarcoma in Malawi

Kaposi sarcoma (KS) is a common childhood cancer in Malawi, but few studies have explored clinical characteristics of relapsed disease. We aimed to characterize clinical patterns of relapse to improve treatment and, ultimately, long-term survival in patients with pediatric KS. A retrospective cohort study was conducted among patients ages <19 years of age at time of KS diagnosis in Lilongwe, Malawi between August 1, 2010 and March 15, 2020. Specifically, emphasis was placed on patients who had relapsed disease and excluded patients with refractory disease or those who died whilst receiving front-line treatment. Salvage therapy typically involved an intensified chemotherapy regimen compared to front-line therapy - namely nonliposomal doxorubicin plus bleomycin/vincristine or paclitaxel monotherapy. One-hundred and ninety patients with pediatric KS were included in this analysis, 50 of whom experienced relapse (26%). Older median age was associated with occurrence of relapse (10 vs. 6.7 years, <i>p</i>-value = 0.004). Median time from diagnosis to first relapse was 10.6 months (range 2.3-49 months). Three-year post-relapse overall survival (OS) for the entire cohort was 60% with a median follow-up time of 4.7 years after relapse. Survival was significantly higher for patients who relapsed with the woody edema clinical phenotype of pediatric KS versus those with visceral/disseminated disease - 3-year OS 79% (95% CI 62-100) vs. 29% (14-61). These data demonstrate potential for continued survival after KS relapse in the pediatric population and identify subsets of high-risk patients. The higher mortality observed in patients with visceral/disseminated KS highlights the need for improved therapeutic strategies.