BACKGROUND To compare the outcomes of gastric, colon, lung, and breast cancer patients with and without rheumatic diseases (RD).

METHODS This retrospective study compared the cancer survival rates of a cohort of 122 cancer patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), dermatomyositis/polymyositis (DM/PM), or systemic sclerosis with that of a cohort of 366 age-, sex-, and, cancer type-matched patients without RD who received medical care from 2000 to 2014. Staging, comorbidities, and functional status were ascertained. Survival was compared using the Kaplan-Meier method. Relative risk of death was estimated as a hazard ratio (HR) using Cox regression analysis.

RESULTS The mean age of the RD patients at the time of cancer diagnosis was 58.7 ± 11.5 years. The overall survival rate of gastric cancer patients did not differ between the cohorts. The survival of lung or breast cancer was worse in patients with RA or DM/PM than in those without RD (all, p < 0.05). After adjusting for cancer stage, comorbidity index, performance status and age at the time of cancer diagnosis (as well as interstitial lung disease for lung cancer group), the mortality rate among lung cancer patients with RA was significantly higher (HR, 1.81; 95 % CI, 1.03-3.18) than that of lung cancer patients without RD, whereas SSc was associated with decreased mortality of lung cancer (HR, 0.16; 95 % CI, 0.04-0.58). DM/PM were associated with increased mortality of breast cancer patients (HR, 297.39; 95 % CI, 4.24-20842.33).

CONCLUSIONS RA and DM/PM seemed to be associated with a higher mortality in patients with lung or breast cancers, whereas SSc seemed to be associated with decreased mortality in patients with lung cancer. It is warranted to explore the survival effect of tailored cancer treatments according to specific RD.