Association between rheumatic diseases and cancer: results from a clinical practice cohort study

Mattia Bellan, Enrico Boggio, Daniele Sola, Antonello Gibbin, Alessandro Gualerzi, Serena Favretto, Giulia Guaschino, Ramona Bonometti, Roberta Pedrazzoli, Mario Pirisi, Pier Paolo Sainaghi

The association between cancer and immune-mediated rheumatic conditions is controversial, especially as far as polymyalgia rheumatica (PMR) is concerned. Furthermore, no clinical feature has been shown to be suggestive of a paraneoplastic rheumatic syndrome. With the present study, we aim to address both these issues. The study population comprised N = 1750 patients, including N = 100 with PMR, who attended our tertiary immuno-rheumatology clinic between January 1, 2005 and November 30, 2012. A rheumatic disease was deemed paraneoplastic if cancer had been diagnosed in the 2 years preceding or following its onset. The probability of a significant association between a specific rheumatic disease and cancer was evaluated by computing the odds ratio (OR): N = 702 patients with osteoarthritis serving as controls. Furthermore, clinical features distinguishing paraneoplastic rheumatic diseases were searched for by univariate and multivariate analysis. Sjogren's syndrome (SS) [OR 3.6 (CI 95% 1.7-7.5)], PMR (OR 5.1 CI 95% 2.9-8.9), dermatomyositis/polymyositis [OR 12.09 (CI 95% 2.6-55.8)] and vasculitis [OR 3.70 (CI 95% 1.81-7.52)] are associated with cancer. At multivariate analysis, older age is associated with cancer among SS patients (p = 0.03), while in the PMR group, older age, male gender, and ≥6 tender joints are independent predictors of paraneoplastic PMR (p < 0.0004). Cancer frequently either heralds or follows rheumatic manifestations, including PMR. Older age, male gender and a more extensive joint involvement should be considered red flags for paraneoplastic PMR.