Intraoperative radiotherapy for rectal carcinoma.

Local recurrence following curative resection of rectal carcinoma is still a major problem. Recurrence rates of more than 30% have been reported in the past, but total mesorectal excision has reduced the incidence to considerably less than 10%. Still, the severe morbidity associated with local recurrence demands additional efforts to guarantee local control. Moreover, it may be hoped that a reduction of local recurrence translates into improved overall survival. Postoperative adjuvant radiotherapy allows treatment after precise pathological staging, thus preventing over-therapy. The target area, however, includes radiosensitive tissues such as urinary bladder, ureters and intestines as well as a hypoxic postsurgical tumor bed with potentially reduced radiosensitivity. Neoadjuvant therapy can render resectability in locally advanced tumors and often facilitates sphincter preservation in low rectal cancer [19, 22]. It also reduces the spread of viable tumor cells and seems to decrease side effects concerning the small bowel. Finally radiosensitivity is expected to be better, because tumor cell oxygenation is not compromised preoperatively. Many randomized trials have confirmed that adjuvant as well as neoadjuvant radiotherapy can reduce the incidence of local recurrence in UICC stage II and III rectal carcinoma by half [13] and neoadjuvant accelerated 5×5-Gy radiotherapy was associated with improved survival [20, 11].