2537 - Definitive Chemoradiation Therapy Followed by Immunotherapy (PACIFIC Regimen) in Stage III Large Cell Carcinoma: Assessing Efficacy Relative to Other Major Non-Small Cell Lung Cancer Subtypes
Presenter(s)
C. Huang1, I. Zhang1, A. Saber1, and C. Zhang2; 1University of Nebraska Medical Center, Omaha, NE, 2Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE
Purpose/Objective(s): To investigate if definitive chemoradiation followed by immunotherapy (PACIFIC regimen) is equally beneficial in stage III large cell carcinoma of the lung (LCC) patients compared with dominant subtypes. We hypothesize that there may exist significant differences in overall survival (OS) between large cell neuroendocrine carcinoma (LCNEC), classic large cell carcinoma (cLCC), adenocarcinoma (ADC), and squamous cell carcinoma (SCC) when treated with PACIFIC regimen, i.e., definitive chemoradiation and durvalumab.
Materials/Methods: The data from the National Cancer Database (NCDB) was used for this study. Patients aged 18 and older who received concurrent chemoradiation (within 30 days of each other) followed by immunotherapy and diagnosed with unresectable stage III NSCLC between 2016 and 2020 were included in this study. We divided the study population into four cohorts: patients with ADC, SCC, LCNEC, and cLCC. Multivariable Cox regression analysis was performed to assess the all-cause mortality of stage III LCC patients compared to other NSCLC patients. The multivariable analysis was adjusted for age at diagnosis, sex, insurance status, race and ethnicity, place of living, Charlson-Deyo Comorbidity Index, treatment facility type, neighborhood education level, and median household income.
Results: 13,891 patients received the PACIFIC regimen, among whom 6,634 patients were diagnosed with adenocarcinoma (ADC), 7,095 patients were diagnosed with squamous cell carcinoma (SCC), 91 patients with large cell neuroendocrine carcinoma (LCNEC), and 71 patients were diagnosed with classic large cell lung cancer (cLCC). Median OS of ADC patients (52.17 [95% CI: 49.5-60.5] months) was significantly longer than median OS of LCNEC patients (34.56 [95% CI: 24.0-44.9] months). Patients with SCC also had better survival than LCNEC patients with a median OS of (38.8 [95% CI: 37.0-40.5] months) while cLCC patients had a similar median OS to LCNEC patients (34.9 [95% CI: 33.6 - not reached] months). There was no difference in the median OS of patients diagnosed with cLCC and ADC or SCC. Overall, patients diagnosed with ADC or SCC had significantly better OS compared to those with LCNEC (HR: 0.52, 95% Cl:0.37-0.74; p=0.001 and HR: 0.70, 95% CI: 0.50-0.98; p=0.04) respectively, but not so compared with those with cLCC. Data suggested reduced mortality of patients diagnosed with cLCC (HR: 0.66, 95% CI: 0.37-1.16; p=0.15) compared with those with LCNEC but the difference was not statistically significant.
Conclusion: The PACIFIC regimen had significantly inferior survival outcomes in LCNEC patients compared to ADC or SCC patients. The PACIFIC regimen may be a reasonable option for patients with cLCC but needs validation. Future investigation of LCC particularly LCNEC for developing novel therapy to improve the outcome is needed for this aggressive form of lung cancer.