Induction of a Pathological Complete Response by Four Courses of Neoadjuvant Chemotherapy for Gastric Cancer: Early Results of the Randomized Phase II COMPASS Trial

Background The prognosis for stage 3 gastric cancer is not satisfactory, even with S-1 adjuvant chemotherapy. A randomized phase II trial was conducted to compare two and four courses of neoadjuvant S-1/cisplatin (SC) and paclitaxel/cisplatin (PC) using a two-by-two factorial design for locally advanced gastric cancer. The primary endpoint was overall survival. We clarified the impact of these regimens on the secondary endpoints, including the clinical and pathological responses, chemotherapy-related toxicities, and surgical results. Methods Patients received S-1 (80 mg/m 2 for 21 days with 1 week’s rest)/cisplatin (60 mg/m 2 at day 8) or paclitaxel/cisplatin (80 and 25 mg/m 2 , respectively, on days 1, 8, and 15 with 1 week’s rest) as neoadjuvant chemotherapy. Results Eighty-three patients were assigned to arm A (two courses of SC, n = 21), arm B (four courses of SC, n = 20), arm C (two courses of PC, n = 21), and arm D (four courses of PC, n = 21). Pathological response rate was 43 % in arm A, 40 % in arm B, 29 % in arm C, and 38 % in arm D. Pathological complete response was only observed in arms B (10 %) and D (10 %). Most bone marrow toxicities, nausea, vomiting, alopecia, and fatigue were slightly higher but acceptable in arms B and D. Grade 3/4 surgical morbidities were not commonly observed in all four arms. Conclusions Pathological complete response could be induced by four courses of neoadjuvant chemotherapy without a marked increase of toxicities, regardless of a SC or PC regimen.