Intraoperative presacral electron boost following preoperative chemoradiation in T3-4Nx rectal cancer: initial local effects and clinical outcome analysis.

BACKGROUND AND PURPOSE: To analyze early results of a single institution experience using adjuvant intraoperative electron radiation therapy (IOERT) presacral boost in locally advanced rectal cancer following preoperative chemoradiation.Materials and methods: In a 63 month period (March 1995-June 2000), 100 consecutive T(3-4)N(x) rectal cancer patients were treated with preoperative chemoradiation (45-50 Gy plus oral Tegafur or 5-Fluorouracil continuous intravenous infusion), radical surgery and IOERT presacral boost (mean dose, 12.5 Gy; range, 10-15 Gy). Adjuvant chemotherapy (5-FU-leucovorin: 4-6 cycles) was given to 52 patients. The median age was 63 years, and 39 patients were >or=70 years old (65 males). Clinical staging was performed with computed tomography (94%) and/or endorectal ultrasound (71%) categorizing 90 cT(3), 10 cT(4), 20 cN(x), and 36 cN(+). Abdomino-perineal resection was performed in 41 cases. RESULTS: The IOERT cancellation rate was 6%. With a median follow-up of 23 months in IOERT treated patients, three developed pelvic recurrence: one anastomotic and one in the posterior vaginal wall (simultaneously with distant metastatic disease); and one presacral (in-field IOERT) as the only site of initial failure. Distant metastasis has been observed in 14 patients (exceptionally in pT(0-1) downstaged patients: 1/20; 5%). Overall treatment tolerances, including neoadjuvant and surgical segments, were acceptable. The actuarial 4-year estimations of local control, disease-free and overall survival are 94, 75 and 65%, respectively. CONCLUSIONS: IOERT electron boost to the presacral region is feasible to integrate systematically in the intensive combined treatment of locally advanced rectal cancer, including neoadjuvant chemoradiation segment. Topography of pelvic recurrences identified 2/3 relapses located in non-IOERT boosted anatomic intrapelvic sites: posterior vaginal wall and anastomotic suture. Presacral recurrence in locally advanced rectal cancer seems to be of low incidence, in a non-subspecialized academic surgical practice coordinated with a multidisciplinary oncology evaluation context, if an IOERT boost is included as a component of treatment together with preoperative chemoradiation.