High Cancer Burden Among Antiretroviral Therapy Users in Malawi: a Record Linkage Study of Observational HIV Cohorts and Cancer Registry Data.

Background

With antiretroviral therapy (ART), AIDS-defining cancer incidence has declined and non-AIDS defining cancers are now more frequent among HIV-infected populations in high-income countries. In sub-Saharan Africa, limited epidemiological data describe cancer burden among ART users.

Methods

We used probabilistic algorithms to link cases from the population-based cancer registry with electronic medical records supporting ART delivery in the Malawi's two largest HIV cohorts, Lighthouse Trust (LT; 2007-2010) and Queen Elizabeth Central Hospital (QECH; 2000-2010). Age-adjusted cancer incidence rates (IR) and 95% confidence intervals were estimated by cancer site, early versus late incidence periods (4 -24 and >24 months after ART start), and WHO stage among naïve ART initiators enrolled for at least 90 days.

Results

We identified 4,346 cancers among 28,576 persons. Most people initiated ART at advanced WHO stage (LT stage 3/4: 55%; QECH stage 3/4: 66%); 12% of patients had prevalent malignancies at ART initiation, which were predominantly AIDS-defining eligibility criteria for initiating ART. Kaposi sarcoma (KS) had the highest IR (634.7 per 100,000 person-years), followed by cervical cancer (36.6). KS incidence was highest during the early period 4-24 months after ART initiation. Non-AIDS defining cancers (NADC) accounted for 6% of new cancers.

Conclusions

Under historical ART guidelines, NADC were observed at low rates, and were eclipsed by high KS and cervical cancer burden. Cancer burden among Malawian ART users does not yet mirror high-income countries. Integrated cancer screening and management in HIV clinics, especially for KS and cervical cancer, remain important priorities in the current Malawi context.