Purpose: The purpose of this study was to evaluate the short-term preoperative effects of neoadjuvant chemoradiation on anorectal function, excluding the bias of postoperative impairment.
Methods: We analyzed 80 patients on whom preoperative anorectal manometry data were available for both prechemoradiation and postchemoradiation. Patients were divided into 2 groups according to the tumor location; lower rectum (n = 52) and mid rectum (n = 28). The paired t test was used to compare prechemoradiation and postchemoradiation parameters including the mean resting pressure, maximum squeeze pressure, percentage asymmetry of the resting and squeeze sphincter, length of the high-pressure zone, rectal sensory threshold, and rectal compliance.
Results: In patients with a lower rectal cancer, there were significant differences in the percentage asymmetry of the squeeze sphincter (27.81 +/- 6.46 vs 25.38 +/- 5.93%, P < .01), length of the high-pressure zone (2.14 +/- 0.74 vs 2.33 +/- 0.72 cm, P = .05), and rectal compliance (1.14 +/- 0.41 vs 1.02 +/- 0.40 mL/mmHg, P = .04). In patients with midrectal cancer, only the mean resting pressure increased significantly (45.08 +/- 18.57 vs 52.83 +/- 17.87 mmHg, P < .01). Clinical symptom evaluation demonstrated a significant decrease in the number of defecations and the frequency of tenesmus.
Conclusion: Neoadjuvant chemoradiation did not impair overall short-term sphincter function significantly, regardless of the location of the primary tumor. Although there was a decrease in rectal compliance, it seemed that the tumor-downsizing effect compensated the expected worsening of anorectal function in the early postchemoradiation period.