Cancer incidence in familial Mediterranean fever patients: a retrospective analysis from central Anatolia

Although chronic inflammation has been associated with increased cancer risk in various disease including hepatitis or inflammatory bowel disease, a lower incidence of cancer has been reported recently in familial Mediterranean fever (FMF) which is an auto-inflammatory disease with persistent inflammation. We have assessed cancer incidence among FMF patients with or without amyloidosis to investigate this hypothesis. We performed a retrospective review of FMF patients, diagnosed and treated in Hacettepe University hospitals between 2001 and 2018. We identified patients from the hospital medical records using the ICD-10 code for FMF. We collected data on demographic and clinical features, drug history, the presence of amyloidosis and subsequent diagnosis of cancer. The expected cancer incidence was estimated using age- and gender-specific standardized incidence rates (SIRs) in comparison with the general Turkish population according to Turkish National Cancer Registry data at 2014. Total of 3899 FMF patients (120 patients had also amyloidosis) were included. Median age was 22 and 56% were females. Thirty-eight patients were diagnosed with cancer during 100,283 person-years of follow-up. The most common cancer was breast cancer in females (7/28 patients) and leukemia (2/10 patients) in males. The overall cancer incidence among patients with FMF was significantly lower in both males {SIR 0.42 [95% confidence interval; (CI) 0.21-0.75], p = 0.019} and females [SIR 065 (95% CI 0.44-0.93), p = 0.002]. The overall cancer incidence among patients with FMF and amyloidosis was [SIR 1.21 (95% CI 0.49-2.52), p = 0.73] without gender difference. Cancer incidence was significantly lower in FMF patients compared with the general Turkish population. We found no increased cancer incidence in FMF patients having amyloidosis. Possible underlying mechanisms need to be explained.