The association between anal function and neural degeneration after preoperative chemoradiotherapy followed by intersphincteric resection.

Background: Preoperative chemoradiotherapy for rectal cancer is administered to improve local control, but it can also induce severe anal dysfunction after surgery.

Objective: The goals of the study were to assess the influence of preoperative chemoradiotherapy on pathological findings and to examine the correlation of these findings with the cause of severe anal dysfunction after intersphincteric resection.

Design: Peripheral nerve degeneration was evaluated histopathologically with the use of hematoxylin and eosin-stained sections of surgical specimens after intersphincteric resection, based on karyopyknosis, vacuolar degeneration, acidophilic degeneration of cytoplasm, denucleation, and adventitial neuronal changes. Each item was scored to quantify the level of neural degeneration, and the relationship between degeneration and anal function was examined at 12 months after closure of the stoma. Anal function was assessed by questionnaire, and incontinence was evaluated based on the Wexner score.

Setting: This study was conducted at the National Cancer Center Hospital East from 2001 to 2006.

Patients: The subjects were 68 patients with lower rectal cancer who underwent intersphincteric resection with (n = 47) or without (n = 21) preoperative chemoradiotherapy.

Main Outcome Measures: The findings in the 2 groups were compared to clarify the association between the degree of histological degeneration and postoperative anal function.

Results: Neural degeneration was significantly higher in the chemoradiotherapy group, and the neural degeneration and Wexner scores had a significant correlation (P = .003, r = 0.477).

Conclusion: Preoperative chemoradiotherapy induced marked neural degeneration around the rectal tumor. The significant correlation between the degeneration score and postoperative anal function suggests that this score may be a useful marker to predict the influence of preoperative chemoradiotherapy on anal function after surgery.