Postoperative chemoradiotherapy in patients with locally advanced gastric cancer with poor pathologic response to neoadjuvant chemotherapy

Purpose: To evaluate the effect of postoperative chemoradiotherapy (CRT) in patients with locally advanced gastric cancer (LAGC) who respond poorly to neoadjuvant chemotherapy (ChT). Materials and Methods: The database of a tertiary medical center (2009-2020) was retrospectively reviewed for patients with LAGC in whom the initial treatment strategy consisted of perioperative ChT and surgery. Those who were subsequently referred for postoperative CRT because of a poor pathologic primary-tumor response (ypT3-4, ypN2-3, R1 resection) were selected for the study. CRT consisted of 45 Gy in 25 fractions of 1.8 Gy combined with capecitabine 825 mg/m2 twice daily on radiotherapy days or continuous infusion of 5-fluorouracil 180 mg/m2/day. Results: The cohort included 26 patients of median age 61 years with LAGC (clinical stage IIA-III) after surgery with D1-D2 lymphadenectomy. R0 resection was achieved in 15 (58%). The pathological stage was III in 69% (IIA-IVA). Treatment was well tolerated. During a median follow-up time of 39 months, recurrences were documented in 14 patients (54%): 11 distant and 3 locoregional. Median progression-free survival was 23 months, and median overall survival was 65 months. Estimated 5-year survival rates were 42 and 54%, respectively. Conclusions: This small retrospective study suggests that in patients with LAGC who show a poor pathologic response to neoadjuvant ChT, a good outcome relative to reference arms in randomized trials can still be achieved with the addition of postoperative CRT. Further studies of the benefit of a tailored adaptive treatment approach to LAGC based on the response to neoadjuvant ChT are warranted.