Significance of postoperative adjuvant immunochemotherapy after curative resection of colorectal cancers: Association between host or tumor factors and survival

We examined the relationship between host as well as tumor factors and postoperative survival rate in patients who received combination therapy of mitomycin C + fluoropyrimidine oral antineoplastics + protein-bound polysaccharide K (PSK) (MFP therapy) after curative resection of colorectal cancer. Markers that determine prognosis, such as preoperative humoral factors (complement 3 and 4), immunosuppressive acidic protein (IAP), lymphocyte transformation (cellular factors) induced by phytohemagglutinin (PHA), pokeweed mitogen (PWM), and PSK, and various tumor markers (CEA, CA19-9) were measured. For each parameter, patients were divided into a high-level and a low-level group according to a predetermined cut-off value, and survival rates were compared between the two groups. The host factors that determined prognosis were 1-month postoperative IAP level [IAP(1M)], preoperative PHA value, and preoperative CA19-9 level. The levels of IAP(1M) <740 μg/ml, preoperative PHA ≥210 (SI value), and preoperative CA19-9 <13 U/ml were associated with a favorable prognosis. When combined with the tumor factors, the prognosis was favorable in Dukes A+B cases with preoperative CA19-9 <13 U/ml, and in Dukes C cases with preoperative PHA ≥210 SI. By the Cox proportional hazard model analysis, among IAP, PHA and CA19-9, CA19-9 was the strongest host factor associated with the prognosis of MFP therapy.