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.