Malignancy as a comorbidity in rheumatic diseases: a retrospective hospital-based study

Patients with Rheumatic diseases (RDs) are at an increased risk of malignancies compared with the general population. The aim of this study was to examine the relative frequency of several cancers in a single homogeneous cohort of patients with different RDs. Patients diagnosed with rheumatoid arthritis (RA), Ankylosing spondylitis (AS), Sjögren's syndrome (SS), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), dermatomyositis (DM), or polymyositis were included. Out of 3982 adult residents admitted to the division of rheumatology, 61 malignancies were observed. The 2009 National Central Cancer Registry (NCCR) of China served as the reference for calculating standardized ratio (SR). The malignancy frequency had no difference between RDs with malignancy and the general population. Patients with SS and DM/PM showed an increased risk of non-Hodgkin's lymphoma (SR for SS patients = 9.709, 95% confidence interval (CI) = 4.602 to 17.916; SR for DM/PM = 35.714, 95% CI = 25.001 to 49.527). Patients with DM/PM and SSc showed an increased risk of lung cancer (SR for DM/PM = 10.638, 95% CI = 5.245 to 19.131; SR for SSc patients = 7.752, 95% CI = 3.295 to 15.309). Patients with SS and DM/PM showed an increased risk of ovary cancer (SR for SS patients = 8.177, 95% CI = 3.566 to 15.888; SR for DM/PM = 32.258, 95% CI = 22.126 to 45.490). Patients with SLE showed an increased risk of cervix cancer (SR for AS patients = 6.897, 95% CI = 2.748 to 14.144). Patients with AS showed an increased risk of pancreas cancer (SR for AS patients = 7.576, 95% CI = 2.181 to 15. 071). Different RDs have an increased risk of particular cancers. Among hematologic cancers, the risk of non-Hodgkin's lymphoma was higher than general population. Among solid tumors, the risk of cancers of the lung, ovary, cervix, and pancreas was higher than general population.