Effects of an oral elemental nutritional supplement in gastric cancer patients with adjuvant S‐1 chemotherapy after gastrectomy: A multicenter, open‐label, single‐arm, prospective phase II study (OGSG1108)

Aim Post‐surgical weight loss influences chemotherapy compliance and may be a risk factor for survival. Intake of an oral elemental nutritional supplement (OENS) can reduce weight loss after gastric cancer (GC) surgery. We assessed whether therapy completion levels would increase in patients receiving postoperative adjuvant chemotherapy in combination with an OENS. Methods This was a multicenter, open‐label, single‐arm, phase II study in GC patients who underwent curative total or distal gastrectomy (TG/DG) and received adjuvant S‐1 chemotherapy. The primary endpoint was the S‐1 completion rate for 1 year with a relative performance (RP) value of ≥70%; secondary endpoints included factors affecting the completion rate of S‐1, RP value after eight S‐1 courses, S‐1 and OENS persistence rates, nutritional index, OENS compliance, and safety. Results In 71 efficacy‐evaluable patients, the S‐1 completion rate was 69.0% (TG, 68.0%; DG, 69.6%) and the RP value was 87.5 (TG, 89.1; DG, 87.5). Over eight treatment courses, median persistence rates were 89.0% for S‐1 and 93.8% for the OENS. The mean OENS compliance was 81.8% at the fourth S‐1 course and 52.9% at the eighth course. The incidence of Grade 3 or 4 adverse events was 27.2%, most commonly neutropenia (12.3%). Conclusions The completion rate of S‐1 for 1 year in patients who could take the OENS exceeded the pre‐defined threshold level. Randomized controlled trials are warranted to confirm the role of OENS in adjuvant chemotherapy.