Immunochemotherapy with PSK and fluoropyrimidines improves long-term prognosis for curatively resected colorectal cancer.

Long-term survival, which extends beyond 5 years, is a desired outcome for colorectal cancer patients. In the present study, we retrospectively compared the 10-year overall survival between the control group and the polysaccharide kureha (PSK) group and analyzed the factors influencing the prognosis. The control group was treated exclusively with oral fluoropyrimidines, whereas the PSK group was treated with fluoropyrimidines, given in conjunction with PSK for 24 months. The 10-year survival rates for the PSK group (81.9%) were significantly superior to those of the control group (50.6%). In Dukes' C cases, the 10-year overall survival rates for the PSK group were also significantly higher than those of the control group. In cases with lymphatic invasion graded ly2-ly3 or venous invasion graded v2-v3, the 10-year overall survival rates were 80.6% in the PSK group, which were significantly superior, compared to 25.9% in the control group. Analysis by Cox's proportional hazard model showed a significant difference between the control and PSK groups. These results indicate that postoperative adjuvant immunochemotherapy with PSK greatly improves prognosis at 10 years. On the basis of these results, we recommend postoperative adjuvant immunochemotherapy combined with PSK for patients with Dukes' C and in cases with ly2-ly3 or v2-v3 invasion.