Differences in tissue degeneration between preoperative chemotherapy and preoperative chemoradiotherapy for colorectal cancer.

Purpose: Preoperative chemoradiotherapy (CRT) for rectal cancer is administered to improve local control, but can also induce severe anal dysfunction after surgery, while preoperative chemotherapy that significantly reduces the primary lesion in rectal cancer has recently been developed. The aim of the study was to examine differences in the effects of preoperative CRT and chemotherapy on tissue degeneration of patients with colorectal cancer.

Methods: The subjects were 91 patients, including 68 with rectal cancer who underwent internal sphincteric resection with (n = 47, CRT group) or without (n = 21, control group) preoperative CRT, and 23 with colorectal cancer who received preoperative FOLFOX treatment. Peripheral nerve degeneration was evaluated histopathologically using H&E-stained sections, based on karyopyknosis, disparity of the nucleus, denucleation, vacuolar or acidophilic degeneration of the cytoplasm, and adventitial neuronal changes.

Results: The incidence of neural degeneration was significantly higher in the CRT group than in the control group and FOLFOX group. There were no differences in any items of neural degeneration between the FOLFOX and control groups.

Conclusion: CRT induced marked neural degeneration around the rectal tumor. FOLFOX treatment produced mild neural degeneration similar to that in the control group.