Objectives: To investigate the relative risk of cancer in Chinese patients with connective tissue diseases (CTD) associated with and without dermatomyositis or polymyositis.
Methods: A retrospective, multicenter cohort study investigated 32,380 CTD patients (2334 diagnosed with dermatomyositis or polymyositis) without a history of malignancies treated from January 1, 1997, to December 31, 2011. Standardized incidence ratios (SIR) of cancers determined the incidence of malignancies during follow-up. The data was compared with the cancer morbidity of the general population from the Chinese Cancer Registry Annual Report of National Central Cancer Registry.
Result: A total of 113 patients (348.98 per 100,000) developed cancer during follow-up, 75 (249.62 per 100,000) were patients with CTD without dermatomyositis or polymyositis. The risk of cancer among patients with CTD was increased (SIR=1.45, 95% confidence interval [CI] 1.22-1.71), and this risk increased with age (<40 years: SIR=1.00 [95%CI 0.45-2.21]; 41-60 years: SIR=1.53 [95%CI 1.17-2.00]; and >60 years SIR=2.34 (95%CI 0.93-2.77]) and the time of follow-up (<1year: SIR=1.22 [95%CI 0.88-1.70]; 1-5 years: SIR=1.14 [95%CI 0.79-1.65]; and 6-10 years SIR=1.70 [95%CI 1.34-2.85]), but was similar between genders (male SIR=1.60 [95%CI 1.10-2.31] and female SIR=1.25 [95%CI 1.01-1.55]). The cancer risk among CTD patients without dermatomyositis or polymyositis was not affected (SIR=0.93, 95%CI 0.75-1.16), regardless of gender, age, or follow-up.
Conclusion: The cancer risk for patients with CTD without dermatomyositis or polymyositis was not increased or decreased, but it was increased when patients with dermatomyositis or polymyositis were included.
Keywords: Autoimmune diseases; Cancer; Connective tissue diseases; Risk factors; Standardized incidence ratios.
Copyright © 2016 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.