EFFICACY OF POSTOPERATIVE ADJUVANT ORAL IMMUNOCHEMOTHERAPY IN PATIENTS WITH DUKES' B COLORECTAL CANCER

Among 370 patients who underwent radical resection of primary colorectal cancer over a 17-year period, 167 had stage II-Dukes' B cancer. After excluding 10 patients treated with intravenous drugs other than 5-FU or hepatic arterial injection and 11 patients with rare histological types other than typical differentiated adenocarcinoma, the remaining 146 patients were used to assess the utility of Japanese-style oral postoperative adjuvant immunochemotherapy. Ninety-one patients who received oral chemotherapy with/without immunotherapy as postoperative adjuvant therapy had a 5-year survival rate of 89.1%, while the rate was 66.5% for patients without such therapy (non-chemotherapy; n=55, p=0.0015). When the 91 patients were divided into those treated with chemotherapy plus immunotherapy (immunochemotherapy; n=61) and those treated with chemotherapy alone (chemotherapy-only; n=30), the 5-year survival rates of the immunochemotherapy, chemotherapy-only, and non-chemotherapy groups were 92.2%, 83.5%, and 66.5%, respectively (immunochemotherapy vs. non-chemotherapy, p=0.0022). When 30 patients were selected from each of the 3 groups and compared by the propensity score matching method, a significant difference was found between the immunochemotherapy and chemotherapy-only groups (p=0.0364), as well as between the immunochemotherapy and non-chemotherapy groups (p=0.0055). These results suggest that Japanese-style oral immunochemotherapy is useful as postoperative adjuvant therapy in patients with stage II-Dukes' B colorectal cancer.