Risk and Prognosis factors for Systemic Sclerosis with Lung Cancer: A Single‐Center Case‐control Study in China

OBJECTIVE To analyse clinical characteristics, risk and prognosis factors for systemic sclerosis (SSc) patients with lung cancer. METHODS SSc patients with lung cancer admitted to Peking Union Medical College Hospital from February 1992 to December 2018 were included. Age and sex-matched controls were selected from a pool of SSc patients without lung cancer during the same period. Conditional logistic regression and Cox proportional-hazard regression were used to identify risk factors and prognosis factors. The Kaplan-Meier method was used to draw the survival curve and calculate median survival. RESULTS Nineteen SSc patients with lung cancer and 76 controls were included. The mean age at lung cancer diagnosis was 54.4 ± 10.2 years. In all 19 cases the lung cancer had been diagnosed after SSc and the median interval between SSc onset and lung cancer onset was 10.5 years (range 2.0-36.2 years). Among SSc patients with lung cancer, the median follow-up time and median survival were 2.6 years and 1.4 years, respectively. In the sex and age-matched conditional logistic multivariable regression analysis, family history of malignancy (OR 4.930, 95%CI 1.926-12.619, P = .001), ILD (OR 7.701, 95%CI 1.009-58.767, P = .049) were independent risk factors for lung cancer among SSc patients, and considering sex and age of SSc onset, SSc patients with more advanced staging of lung cancer (HR 3.190, 95%CI 1.127-6.126, P = .06) had poorer prognosis. CONCLUSION Lung cancer is not uncommon in SSc patients, especially those with family histories of malignancy or ILD. Early detection of lung cancer is of vital importance for better prognosis.