BRCA2 and small cell lung carcinoma: We also summarized the molecular characteristics at disease progression and found the possible resistant mechanisms included sarcomatous degeneration and secondary gene mutation, of which one patient with pancreatic cancer was found to be with multiple BRCA2 truncation mutation, two patients with A2M mutation (SCLC and sarcoma), one with JAK1 mutation (pancreatic cancer), T790M mutation (cervical cancer), KEAP1 (prostate cancer) and mTOR mutation (NSCLC), respectively.