[Adjuvant immunochemotherapy with long-term OK-432 administration in colorectal cancer]

A new clinical trial on immunochemotherapy as an adjuvant therapy of surgery for colorectal cancers was studied. Results were retrospectively evaluated against previous controls treated by chemotherapy alone. As an immunotherapeutic agent, a streptococcal preparation, OK-432 was used. The maintenance dosage of OK-432, was 5 KE once a week and was continued for at least 2 years after surgical resection. As chemotherapeutic agents, mitomycin C for 2 weeks postoperatively and tegafur for 1 year were administered. Delayed skin reactivity to SU-polysaccharide (SU-PS) extracted from Streptococcus pyogenes SU-strain and lymphoproliferative response to phytohemagglutinins (PHA) were significantly enhanced in the OK-432, immunochemotherapy group. Disease-free interval in the immunochemotherapy group (n = 49) was prolonged compared to that in the control group (n = 129), especially in the curative resection cases of Duke's C stage. There was statistical significance between the two groups (p less than 0.05). These results suggested that long-term administration of OK-432 after surgical resection of colorectal cancer was effective on growth inhibition of micrometastasis and could increase the postoperative survival rate.