Preoperative radiotherapy in rectal cancer: treatment results of three different dose regimens

Radiotherapy (RT) prior to surgery could benefit patients with advanced rectal adenocarcinoma. This study was designed to examine the preoperative therapeutic effect of RT given in different doses and fractions, depending on clinical (c) TN stage and on tumor site in the rectum.

From 1997 to 2002, 122 patients with adenocarcinoma of the lower two thirds of the rectum and cT2-4, N0-2, M0, were treated with preoperative RT and then were operated radically. Patients with postoperative pathological (p) T4 and/or N+ received 4-6 cycles of 5-fluorouracil (5-FU) and leucovorin chemotherapy. RT was performed using 3 different schemes. Thirty-eight patients received 4 Gy daily in 5 consecutive days and operated within 3-5 days after RT. Doses of 5 Gy daily in 5 consecutive days were delivered to 51 patients who were also operated within 3-5 days post-RT. Another 33 patients received 50 Gy in 25 fractions of 2 Gy each in 5 weeks and were operated not later than 30-45 days post-RT. The average follow-up period was 53 months. Conventional and conformal techniques were used for RT. The influence of various factors (stage, histological subtype, distance from dentate line, type of surgery, number of nodes involved) were analyzed.

Overall survival for all 122 patients at 3 years was 84%. The distant metastasis-free survival was 82%, the local recurrence-free survival 92%; for stage III only it was 88%. Overall survival, distant metastasis and local recurrence rate were significantly influenced by the pathological stage (p <0.05). Local recurrence and distant metastasis were significantly higher in patients with more than 3 nodes involved (p <0.005). The influence of the different RT dose regimens showed a tendency to reduced local recurrence free survival in patients receiving a dose lower than 40 Gy. The use of short preoperative schemes increased the rate of local recurrences in cases with low anterior resections. A reduction in tumor size with 50 Gy of conventional RT was established and downstaging was achieved in 54% of the cases. No late effects on normal tissues were observed with any scheme of preoperative RT.

The conventional preoperative RT at 50 Gy dose levels proved more effective for advanced rectal cancer (T4 or N2) and for low anterior resections. The short scheme 5 x 5 Gy was appropriate for less advanced tumors (T2-3, N0-1), something requiring accurate clinical staging.