Characteristics and prognosis of EGFR mutations in small cell lung cancer patients in the NGS era.

Purpose: Targeted therapy has not been effective for small cell lung cancer (SCLC) patients. Although some studies have reported on EGFR mutations in SCLC, a systematic investigation into the clinical, immunohistochemical, and molecular characteristics and prognosis of EGFR-mutated SCLCs is lacking. Methods: Fifty-seven SCLC patients underwent next-generation sequencing technology, with 11 in having EGFR mutations (group A) and 46 without (group B). Immunohistochemistry markers were assessed, and the clinical features and first-line treatment outcomes of both groups were analyzed. Results: Group A consisted primarily of non-smokers (63.6%), females (54.5%), and peripheral-type tumors (54.5%), while group B mainly comprised heavy smokers (71.7%), males (84.8%), and central-type tumors (67.4%). Both groups showed similar immunohistochemistry results and had RB1 and TP53 mutations. When treated with tyrosine kinase inhibitors (TKIs) plus chemotherapy, group A had a higher treatment response rate with overall response and disease control rates of 80% and 100%, respectively, compared to 57.1% and 100% in group B. Group A also had a significantly longer median progression-free survival (8.20 months, 95% CI 6.91–9.49 months) than group B (2.97 months, 95% CI 2.79–3.15), with a significant difference (P = 0.043). Additionally, the median overall survival was significantly longer in group A (16.70 months, 95% CI 1.20–32.21) than in group B (7.37 months, 95% CI 3.85–10.89) (P = 0.016). Conclusion: EGFR-mutated SCLCs occurred more frequently in non-smoking females and were linked to prolonged survival, implying a positive prognostic impact. These SCLCs shared immunohistochemical similarities with conventional SCLCs, and both types had prevalent RB1 and TP53 mutations. [ABSTRACT FROM AUTHOR]