Neoadjuvant radiochemotherapy for patients with locally advanced rectal cancer leads to impairment of the anal sphincter

Neoadjuvant radiochemotherapy (RCTx) has become an acceptable therapy for patients with locally advanced rectal cancer. However, little is known about the effect of the RCTx on the function of the anal sphincter. Forty-one consecutive patients with locally advanced rectal cancer (cT3, N+) underwent neoadjuvant RCTx with subsequent resection. All patients were examined clinically and by anal manometry for their anal sphincter function. A multichannel water-perfused catheter system was used, and resting pressure, maximum squeeze pressure, and length of the anal high-pressure zone were determined prior to the neoadjuvant therapy and before the operation. The length of the high-pressure zone did not change after the neoadjuvant therapy. However, resting and maximum squeeze pressure decreased significantly after preoperative RCTx. This effect was more pronounced for the resting pressure rather than the maximum squeeze pressure, indicating that the internal sphincter is primarily affected. These results correlated with the clinical data showing an impaired continence status in patients treated with neoadjuvant therapy. Neoadjuvant RCTx leads to impairment of the anal sphincter predominantly in the internal sphincter. This effect may enhance the surgical impairment of continence after curative resection.