CLO19-040: The Role of Adjuvant Therapy in Patients With Pathological T2N0 Resected Gastric Adenocarcinoma

Background: There is controversy surrounding the benefit of adjuvant therapy for patients with pT2N0, stage IB gastric adenocarcinoma following surgical resection. Methods: Patients with T2N0 gastric adenocarcinoma (tumor invasion into the muscularis propria) who underwent surgical resection with pathological evaluation of at least 15 lymph nodes were identified from the Surveillance Epidemiology and End Results Registry (SEER) database. Demographics, adjuvant therapy, and survival data were collected and analyzed using SPSS statistical software. Results: A total of 452 cases were identified between 2004 and 2014. Median age at diagnosis was 69. 60.2% of the patients were white, 27.7% Asian, 10.8% black, and 1.3% from other races. Adjuvant therapy was administered to 30.5% of the patients, of which 44.2% received chemoradiation, 48% chemotherapy only, and 7.2% radiation therapy only. After a median follow up of 39 months, the median overall survival (OS) was not reached in the group of patients who received adjuvant therapy versus 100 months in the group that did not receive adjuvant therapy (P=.005). The 5-year OS rate (5-YOS) was 77% for the adjuvant therapy group versus 62% for those who did not receive adjuvant therapy. Univariate analysis revealed that the hazard ratio for death [adjuvant therapy vs observation] was 0.54; 95% CI, 0.35 to 0.83. Adjuvant therapy showed statistically significant survival benefit in patients younger than 60 years of age (5-YOS, 95% vs 79%) and failed to show survival benefit in patients older than 60 (5-YOS, 63% vs 58%). Multivariate analysis revealed that age was associated with mortality, whereas sex, race, grade, tumor size, and number of lymph nodes examined were not associated with increased mortality. Conclusions: Adjuvant therapy provided survival benefit for pT2N0, stage IB resected gastric adenocarcinoma. Our results suggest that patients younger than 60 year of age may benefit the most from this therapy.