Cancer incidence among people living with HIV in Zimbabwe: a record linkage study

BACKGROUND: People living with HIV (PLWH) are at increased risk of developing cancer. Cancer diagnoses are often incompletely captured at antiretroviral therapy (ART) clinics. AIM: To estimate the incidence and explore risk factors of cancer in a cohort of PLWH in Harare using probabilistic record linkage (PRL). METHODS: We conducted a retrospective cohort study that included PLWH aged ≥16 years starting ART between 2004 and 2017. We used PRL to match records from the Zimbabwe National Cancer Registry (ZNCR) with electronic medical records from an ART clinic in Harare to investigate the incidence of cancer among PLWH initiating ART. We matched records based on demographic data followed by manual clerical review. We followed PLWH up until first cancer diagnosis, death, loss to follow-up, or 31 December 2017, whichever came first. RESULTS: We included 3442 PLWH (64.9% female) with 19 346 person-years (PY) of follow-up. Median CD4 count at ART initiation was 169 cells/mm(3) (interquartile range [IQR]: 82-275), median age was 36.6 years (IQR: 30.6-43.4). There were 66 incident cancer cases for an overall incidence rate of 341/100 000 PY (95% confidence interval [CI]: 268-434). Twenty-two of these cases were recorded in the ZNCR only. The most common cancers were cervical cancer (n = 16; 123/100 000 PY; 95% CI: 75-201), Kaposi sarcoma, and lymphoma (both n = 12; 62/100 000 PY; 95% CI: 35-109). Cancer incidence increased with age and decreased with higher CD4 cell counts at ART initiation. CONCLUSION: PRL was key to correct for cancer under-ascertainment in this cohort. The most common cancers were infection-related types, reinforcing the role of early HIV treatment, human papillomavirus vaccination, and cervical cancer screening for cancer prevention in this setting.