Characteristics and predictors of malignancy in dermatomyositis: Analysis of 239 patients from northern China

The present study aimed to determine the characteristics of patients with dermatomyositis (DM) in order to identify predictors of cancer in these patients. Data of 239 patients with DM, treated at Yuhuangding Hospital between 1997 and 2016, was retrospectively assessed. The patients' demographic, clinical, survival and laboratory data were analyzed. Of the 239 patients, 43 developed malignancies. In 30 (69.77%) patients, the malignancy was detected within 1 year before or after DM diagnosis. There were 15 (34.88%) fatalities. Lung cancer was the most common type of malignancy identified (n=6, 13.95%), and adenocarcinoma was the most common pathological type (n=6, 13.95%). Older age, absence of interstitial lung disease, and absence of arthralgia were demonstrated to be independent risk factors for malignancy. Myositis-specific autoantibody expression, specifically anti-TIF1γ positivity and/or anti-MDA5 negativity, was associated with cancer in patients with DM. The survival rate was significantly lower in patients with malignancy than in patients without malignancy. Patients with DM had a high incidence of malignancy and a poor prognosis. Lung cancer and adenocarcinoma are common among patients with DM in northern China. Cancer screening should be conducted in all DM patients, particularly within 1 year of DM diagnosis. Older age is a risk factor for malignancy in DM patients, while interstitial lung disease and arthralgia are protective factors. Myositis-specific autoantibody detection may be useful for cancer screening in patients with DM.