Increased incidence of cancer in the follow-up of obstetric antiphospholipid syndrome within the NOH-APS cohort

Malignancies can be associated with positive antiphospholipid antibodies but the incidence of cancer among women with the purely obstetric form of antiphospholipid syndrome (APS) is currently unknown. Our aim was to investigate the comparative incidence of cancers in women with a history of obstetric APS within a referral university hospital-based cohort (NOH-APS cohort). We performed a 17-year observational study of 1,592 non-thrombotic women with three consecutive spontaneous abortions before the 10th week of gestation or one fetal death at or beyond the 10th week of gestation. We compared the incidence of cancer diagnosis during follow-up among the cohort of women positive for antiphospholipid antibodies (n=517), the cohort of women carrying the F5 rs6025 or F2 rs1799963 polymorphism (n=279) and a cohort of women with negative thrombophilia screening results (n=796). The annualized rate of cancer was 0.300% (0.20%-0.44%) for women with obstetric APS and their cancer risk was substantially higher than that of women with negative thrombophilia screening [adjusted hazard ratio (aHR) 2.483; 95% confidence interval (CI) 1.27-4.85]. The computed standardized incidence ratio for women with obstetric APS was 2.89; 95% CI: 1.89-4.23. Among antiphospholipid antibodies, lupus anticoagulant was associated with incident cancers (aHR 2.608; 95% CI: 1.091-6.236). Our cohort study shows that the risk of cancer is substantially higher in women with a history of obstetric APS than in the general population, and in women with a similar initial clinical history but negative for antiphospholipid antibodies.