Specifically, 9.33% of Chinese SCLC patients had pathogenic or likely pathogenic germline gene variants, including BRCA2, BRCA1, ATM, UCP3, GCDH, MPL, SMO, FGFR4 and TP53. Moreover, 24% of patients had a family history of cancer, highlighting the necessity of risk assessment for those patients and their first-degree family members. This evidence concerns the gene SMO and cancer.