MUC1 and interstitial lung disease: KL-6, Krebs von den Lungen-6; ILD, interstitial lung disease; IS, immunosuppressants; BMI, body mass index; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; TLC, total lung capacity; DLco, diffusing capacity for carbon monoxide; NSCLC, non-small cell lung cancer; LC, lung cancer; CCRT, concurrent chemoradiation therapy