Adult T-cell leukemia/lymphoma incidence rate in French Guiana: a prospective cohort of women infected with HTLV-1.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive malignancy caused by the human T-cell leukemia virus type 1 (HTLV-1). The incidence of ATL among HTLV-1 carriers remains largely unknown in endemic countries other than Japan as very few prospective studies have been performed. We assessed the ATL incidence rate among HTLV-1 infected women in a prospective cohort in French Guiana. This is the first prospective study to assess the ATL incidence rate in an area of South America where HTLV-1 prevalence is high. Patients were enrolled between 1991 and 2005, and follow-up continued until April 2018. In the general hospital in Saint-Laurent-du-Maroni, 307 pregnant women were diagnosed with HTLV-1 infection, and 268 of them were observed for a median of 16.7 years. During follow-up, 9 ATL incident cases occurred resulting in an ATL incidence rate of 2.03 per 1000 HTLV-1 carrier-years (95% confidence interval, 0.93-3.85 per 1000 HTLV-1 carrier-years). The median age at diagnosis was 47.4 years, and median survival from diagnosis was low at 3.5 months. The ATL incidence rate was elevated for a study population consisting mostly of young people, which could either be a general feature in South America or could be specific to the Noir Marron population that constituted most of the cohort.