Preoperative radiotherapy reduces rectal cancer recurrences

NEW YORK (Reuters Health) - A short course of preoperative radiotherapy can reduce local recurrences in patients with operable rectal cancer, according to the findings from two studies appearing in the March 7th issue of The Lancet.

The plane of surgery achieved during resection also significantly impacts outcomes. Resections in the mesorectal plane have lower local recurrence rates than those in the intramesorectal or muscularis propria planes.

The first study, conducted by Dr. David Sebag-Montefiore, from St. James' University Hospital, Leeds, UK, and colleagues, involved 1350 patients, with operable adenocarcinoma of the rectum, who were randomized to receive short-course preoperative radiotherapy (25 Gy in five fractions) or selective postoperative chemoradiotherapy (45 Gy in 25 fractions combined with 5-fluorouracil). The patients were restricted to cases with involvement of the circumferential resection margin.

Preoperative radiotherapy reduced the risk of local recurrence by 61% relative to selective postoperative chemoradiotherapy (p < 0.0001) and was tied to an absolute difference of 6.2% at 3 years. The corresponding relative and absolute improvements in disease-free survival were 24% and 6.0%.

No significant differences in overall survival, however, were noted between the groups.

In the second study, Dr. Phil Quirke, from the University of Leeds, UK, and associates looked at the impact of the plane of surgery achieved on the outcomes of 1156 patients drawn from the first study.

A mesorectal plane was achieved in 52% of patients, an intramesorectal plane in 34%, and a muscularis propria plane in 13%. Eleven percent of patients had involvement of the circumferential resection margin.

Local recurrence rates fell as the plane achieved went from muscularis propria to mesorectal. As anticipated, a negative circumferential resection margin was also tied to a lower rate.

At 3 years, the estimated local recurrence rates for patients with mesorectal, intramesorectal, and muscularis propria planes were 4%, 7%, and 13%, respectively. Preoperative chemotherapy was equally beneficial in the three plane groups. Subjects who received preoperative chemotherapy and had a mesorectal plane had a 3-year recurrence rate of just 1%.

In a related editorial, Dr. Robert D. Madoff, from the University of Minnesota, Minneapolis, comments that while the present findings shine light on the appropriate treatment of rectal cancer, two major questions remain. First, what is the best way of giving preoperative radiotherapy, short course or conventional long course combined with 5-fluorouracil. And second, can these adjuvant treatments actually improve overall survival.

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