The use of adjuvant chemotherapy in resected stage IB-IIIA non–small cell lung cancer (NSCLC) and comparison to the TriNetX database.

Abstract

29 Background: Adjuvant cisplatin-based chemotherapy (AC) is the standard of care for completely resected stage IB (tumor size > 4cm), II, and IIIA non small cell lung cancer (NSCLC) patients. Several randomized clinical trials have shown varying levels of survival benefit for patients treated with AC compared to surgery alone. Methods: A retrospective study was performed regarding the use of adjuvant chemotherapy comparing Charleston Area Medical Center (CAMC) patients to those in the TriNetX database in the years 1998-2017. Inclusion criteria were patients > 18 years of age, completely resected (R0), stage IB (tumor size > 4 cm) through stage IIIA (R0) NSCLC. SAS 9.3 was used for data analysis. Results: The populations included two hundred and thirty-six (CAMC) and 4,364 (TriNetX) patients. The CAMC population was 98% Caucasian, 63% male with an average age of 65±10 years. The TriNetX population was 66% Caucasian, 57% male with an average age of 67±10 years. The 5-year overall survival (OS) in the CAMC database between chemotherapy and non-chemotherapy groups was not statistically significant (49.5% vs 49.8%, p = 0.8, respectively). In the TriNetX database, the 5-year OS for the chemotherapy group was significantly higher compared to the non-chemotherapy groups (61.2% vs 54.0%, p < 0.05, respectively). Cox proportional hazards model was used to determine the factors influencing 5-year OS in the CAMC population. Results showed that patients >65 years of age were 2.2 times (95% CI: 1.53-3.2) more likely to be dead in 5-years. With each increase in stage patients were 1.3 times (95% CI: 1.0-1.8) more likely to be dead in 5-years. Moreover, patients without coronary artery disease were 1.7 times (95% CI: 1.2-2.4) more likely to be dead in 5-years. Conclusions: Regardless of treatment, about half of CAMC patients were alive at 5 years, while a higher OS was seen in the TriNetX chemotherapy group. Regression analysis of the CAMC population showed that chemotherapy was not a significant variable in 5-year OS. Differences in survival between CAMC and TriNetX could be due to the large number of comorbidities in the CAMC population, patient refusal to chemotherapy, particularly those >65 years, and incomplete planned dose due to side effects of adjuvant chemotherapy. We conclude that several barriers may impact the use of adjuvant chemotherapy in non-trial settings in the CAMC population.