Neo-adjuvant radiation therapy provides a survival advantage in T3-T4 nodal positive gastric and gastroesophageal junction adenocarcinoma: a SEER database analysis

BACKGROUND: Due to negative results in clinical trials of postoperative chemoradiation for gastric cancer, at present, there is a tendency to move chemoradiation therapy forward in gastric and gastroesophageal junction (GEJ) adenocarcinoma. Several randomized controlled trials (RCTs) are currently recruiting subjects to investigate the effect of neo-adjuvant radiotherapy (NRT) in gastric and GEJ cancer. Large retrospective studies may be beneficial in clarifying the potential benefit of NRT, providing implications for RCTs. METHODS: We retrieved the clinicopathological and treatment data of gastric and GEJ adenocarcinoma patients who underwent surgical resection and chemotherapy between 2004 and 2015 from Surveillance, Epidemiology, and End Results (SEER) database. We compared survival between NRT and non-NRT patients among four clinical subgroups (T(1–2)N(−), T(1–2)N(+), T(3–4)N(−), and T(3–4)N(+)). RESULTS: Overall, 5272 patients were identified, among which 1984 patients received NRT. After adjusting confounding variables, significantly improved survival between patients with and without NRT was only observed in T(3–4)N(+) subgroup [hazard ratio (HR) 0.79, 95% confidence interval (CI): 0.66–0.95; P = 0.01]. Besides, Kaplan-Meier plots showed significant cause-specific survival advantage of NRT in intestinal type (P < 0.001), but not in diffuse type (P = 0.11) for T(3–4)N(+) patients. In the multivariate competing risk model, NRT still showed survival advantage only in T(3–4) N(+) patients (subdistribution HR: 0.77; 95% CI: 0.64–0.93; P = 0.006), but not in other subgroups. CONCLUSIONS: NRT might benefit resectable gastric and GEJ cancer patients of T3–4 stages with positive lymph nodes, particularly for intestinal-type. Nevertheless, these results should be interpreted with caution, and more data from ongoing RCTs are warranted. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-021-08534-9.