Incidence of cancer in a cohort of patients with primary Sjögren syndrome in Argentina

Primary Sjögren syndrome (pSS) is usually a mild disease, but serious complications such as non-Hodgkin lymphoma—and hypothetically other malignancies—may develop. The aim of this study was to evaluate both overall and specific incidence of cancer in a cohort of patients with pSS compared to the expected incidence in general population of Argentina. Retrospective analytic study of pSS patients fulfilling American-European Consensus Group (AECG) criteria, followed from the time of their diagnosis until the end of the study, death, loss of follow- up, or being given a diagnosis of cancer. Cancer incidence for the general population was obtained from GLOBOCAN 2018, and demographic information was obtained from the national institute for statistics and census. Age- and sex-specific Standardized Incidence Ratio (SIR) were then calculated. One hundred fifty-seven patients, with a mean age of 57.8 years (SD 18.3), were included. Mean patient follow-up duration was 7.37 years (SD 4.2), contributing to a total of 1158 patient/years. Fifteen patients developed a malignancy during follow-up. Cancer incidence for pSS patients was compared with the general population’s incidence through SIRs. Female patient’s SIRs for overall cancer was 4.17 (95% CI 2.30–6.87), non-Hodgkin lymphoma 41.40 (95% CI 10.12–102.1), multiple myeloma 41.49 (95% CI 1.14–167.28), tongue cancer 44.4 (95% CI 1.23–177.31), uterus cancer 8.39 (95% CI 0.19–40.73), lung cancer 4.51 (95% CI 0.1–22.16), and breast cancer 3.76 (95% CI 1.04–9.45). An increased overall cancer risk, and particularly for non-Hodgkin lymphoma, multiple myeloma, breast cancer and tongue cancer was observed in female pSS patients compared to control group.