Background: We previously reported that preoperative chemoradiotherapy (CRT) combined with intraoperative electron irradiation for cT3/T4 adenocarcinoma of the rectum reduced the local recurrence, with significant improvement of survival. Radiotherapy has been reported to reduce immune function. We examined the effects of PSK, a protein-bound polysaccharide, concomitant with preoperative CRT on immune responses.
Patients and methods: Thirty patients with cT3/T4 adenocarcinoma of the rectum were randomly assigned to 2 weeks' irradiation and 4 weeks' S-1 administration before surgery (control group), or the same CRT with simultaneous 4 weeks' PSK administration (PSK group). Both systemic and local immune responses were evaluated.
Results: Significant increase of natural killer cell count in the peripheral blood and cytotoxic T-cell counts in the peri-tumoral and normal mucosa, and a significant decrease of serum immunosuppressive acidic protein level were observed in the PSK group.
Conclusion: Combined use of PSK with preoperative CRT may improve immune function.