Effects of adjuvant radiotherapy on completely resected gastric cancer: A radiation oncologist's view of the ARTIST randomized phase III trial.

PURPOSE: We investigated which subgroups might benefit from adjuvant radiotherapy (RT) and suggested optimal RT targets by analyzing the results of the Adjuvant Chemoradiation Therapy in Stomach Cancer (ARTIST) trial.

METHODS: We conducted randomized controlled trial in 458 gastric cancer patients. Patients were randomly assigned to XP (6 cycles of capecitabine and) or XPRT (2 cycles of XP+RT 45Gy/25 fraction with capecitabine+2 cycles of XP) groups after D2 resection. Minimum follow-up was 5years.

RESULTS: During follow-up, 77 patients (33.8%) in the XP arm and 60 (26.1%) in the XPRT arm experienced recurrence. Among these patients, locoregional recurrence (LRR) developed in 44 (9.6%; 29 in XP, 15 in XPRT; P=0.03). The local recurrence rate (4.8%) did not vary between arms. Regional recurrence was the most important difference between the two groups (23 in the XP arm, 5 in the XPRT arm, P<0.001). LRR-free survival (LRRFS) was significantly different between study arms (P=0.03), especially in patients with LN metastasis (P=0.009).

CONCLUSIONS: Adjuvant RT after D2 resection in gastric cancer reduced LRR, especially in group 3 LNs, and improved LRRFS. Patients with LN metastasis benefited more from the adjuvant RT treatment than the other subgroups.