Risk for cancer development in familial Mediterranean fever and associated predisposing factors: an ambidirectional cohort study from the international AIDA Network registries

Objective: Inflammation has been associated with an increased risk for cancer development, while innate immune system activation could counteract the risk for malignancies. Familial Mediterranean fever (FMF) is a severe systemic inflammatory condition and also represents the archetype of innate immunity deregulation. Therefore, the aim of this study is to investigate the risk for cancer development in FMF. Methods: The risk ratio (RR) for malignancies was separately compared between FMF patients and fibromyalgia subjects, Still's disease patients and Beh & ccedil;et's disease patients. Clinical variables associated with cancer development in FMF patients were searched through binary logistic regression. Results: 580 FMF patients and 102 fibromyalgia subjects, 1012 Beh & ccedil;et's disease patients and 497 Still's disease patients were enrolled. The RR for the occurrence of malignant neoplasms was 0.26 (95% Confidence Interval [CI.] 0.10-0.73, p=0.006) in patients with FMF compared to fibromyalgia subjects; the RR for the occurrence of malignant cancer was 0.51 (95% CI. 0.23-1.16, p=0.10) in FMF compared to Still's disease and 0.60 (95% CI. 0.29-1.28, p=0.18) in FMF compared to Beh & ccedil;et's disease. At logistic regression, the risk of occurrence of malignant neoplasms in FMF patients was associated with the age at disease onset (beta 1 = 0.039, 95% CI. 0.001-0.071, p=0.02), the age at the diagnosis (beta 1 = 0.048, 95% CI. 0.039-0.085, p=0.006), the age at the enrolment (beta 1 = 0.05, 95% CI. 0.007-0.068, p=0.01), the number of attacks per year (beta 1 = 0.011, 95% CI. 0.001- 0.019, p=0.008), the use of biotechnological agents (beta 1 = 1.77, 95% CI. 0.43-3.19, p=0.009), the use of anti-IL-1 agents (beta 1 = 2.089, 95% CI. 0.7-3.5, p=0.002).Conclusions: The risk for cancer is reduced in Caucasic FMF patients; however, when malignant neoplasms occur, this is more frequent in FMF cases suffering from a severe disease phenotype and presenting a colchicine-resistant disease.