NEW YORK (Reuters Health) - Chemotherapy and radiation therapy that are used to treat rectal cancer are best given before rather than after the tumor is surgically removed, new research indicates.

Although this "pre-operative" approach doesn't improve patients' survival, it does reduce the risk that the cancer will return and it is less toxic than the "post-operative" approach.

The findings, which appear in this week's New England Journal of Medicine, are based on a study of 823 people with rectal cancer who were treated with either pre-operative or post-operative chemoradiotherapy. All of the subjects had locally advanced rectal cancer -- that is, relatively large tumors that in some cases involved nearby lymph nodes.

With pre-operative therapy, treatment was completed 6 weeks before surgery, and with post-operative therapy, treatment was started 1 month after surgery. Other than these differences, the regimens were essentially the same and included the drug fluorouracil.

After 5 years, nearly the same percentage of patients were alive in each group -- about 75 percent, lead author Dr. Rolf Sauer, of the University of Erlangen in Germany, and colleagues report.

However, tumors were half as likely to return when therapy was given before rather than after surgery.

Also, serious side effects from the therapy were much less common when the treatments were given pre-operatively, the investigators point out.

Despite the lack of a survival benefit, the authors believe that "preoperative chemoradiotherapy is the preferred treatment for patients with locally advanced rectal cancer."

In an editorial on the study, Dr. Robert D. Madoff, from the University of Minnesota at Minneapolis, comments that the study provides "convincing evidence" that pre-operative chemoradiotherapy is superior to post-operative therapy for people with locally advanced rectal cancer.

Still, certain issues remain unresolved, such as the "possibility of overtreating early-stage tumors" and the choice of radiation, he adds.

SOURCE: The New England Journal of Medicine, October 21, 2004.

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