P1.07-020 Surgical Resected Small Cell Lung Cancers (SCLCs): A Monocentric Retrospective Analysis

Abstract

Standard treatment for stage I-III SCLCs is chemoradiotherapy followed by prophylactic cranial irradiation, with 5-year survival rate of about 20%. Recent retrospective analyses reported benefit from surgery followed by adjuvant platinum-based chemotherapy but no randomized trials confirmed these results. A series of 365 SCLCs treated from 1996 to 2015 has been retrospectively evaluated. Among 141 evaluable patients, 61 underwent radical-intent surgery and 21 underwent chemoradiotherapy. Clinical, radiological and pathological data were reviewed and related with outcome. Mitotic count, necrosis, TP53, Bcl-2 and PD-L1 immunohistochemical expression were analyzed. Median follow-up was 42 months. Among resected patients, 46 (75%) were male and median age was 68 (95% CI: 46.9-83.4) years. Seven patients (11%) underwent pneumonectomy, 43 (71%) received chemotherapy before (20%) or after (51%) surgery. Adjuvant radiotherapy was administered in 19 (31%) cases. Pathological review of resected SCLCs was performed. Median mitotic count was 59/10 hpf and extensive necrosis was found in 80% of samples. P53 (>30%), Bcl-2 (H-index >150) and PD-L1 (>5%) expression was reported in 58%, 58% and 62% of samples respectively. None of these factors significantly affected survival. A significant correlation between necrosis and mitosis (p 0.00002), and pN2 and Bcl-2 (p 0.03) was found. Median overall survival (OS) and relapse-free survival (RFS) were 62.3 (95% CI: 32.4-82.1) and 12.8 (95% CI: 6.57-47.27) months, respectively. Mortality of surgery was 0%, morbidity was 23%. Surgical margins were found positive in 8 (13%) cases. Median OS for pN0-1 patients was 65.7 (95% CI: 44.5-108) months versus 30.3 (95%CI: 12-NA) months for patients with pN2 disease (p 0.04). Multivariate analysis confirmed pN2 stage (p 0.04) and surgical margins (p 0.03) as significant prognostic factors. Among non-resected patients, the median age was 69.4 (95% CI: 54.7-84) years. Median OS and RFS were 13.4 (95% CI: 7-26.9) and 7 (95% CI: 5.9-19) months. To confirm our results, we compared outcome of patients with pN2 disease according to surgical resection. Median OS of surgically resected SCLCs was 30.3 (95% CI: 7.03-36.9), while it was 14.7 (95% CI: 12-NA) months among patients treated with chemoradiotherapy, but the comparison was not statistically significant. Radical-intent surgery was feasible and associated with considerable long-term survival. Mediastinal nodal involvement and non-radical surgery were the main elements able to affect OS. The expression of PDL1 was not prognostic in stage I-III SCLCs. Further prospective studies are warranted to optimize multimodal approach and selection of patients.