MedWire News: An intense 3-week course of radiation therapy is just as effective as the standard 5-week regimen for women with early-stage breast cancer, Canadian research shows.

“For women with breast cancer who are similar to the patients in this trial, an abbreviated course of radiation therapy should be more convenient and less costly than standard treatment,” remark Timothy Whelan (Juravinski Cancer Centre, Hamilton, Ontario) and co-authors in the New England Journal of Medicine.

Between 1993 and 1996, the researchers recruited women with invasive breast cancer who had undergone breast-conserving surgery and in whom resection margins were clear and axillary lymph nodes were negative. The women were randomly assigned to receive whole-breast irradiation either at a standard dose of 50.0 Gy in 25 fractions over a period of 35 days (the control group) or at a dose of 42.5 Gy in 16 fractions over a period of 22 days (the hypofractionated-radiation group).

A decade after treatment, the cumulative incidence of local invasive recurrence was 6.7% among the 612 women assigned to receive standard irradiation compared with 6.2% among the 622 women assigned to receive the hypofractionated regimen. The rate of good or excellent cosmetic outcome at 10 years was 71.3% of in the control group compared with 69.8% in the hypofractionated-radiation group.

A subgroup analysis revealed that the hypofractionated regimen appeared to be less effective in patients with high-grade tumors; in this subgroup, the cumulative incidence of local recurrence at 10 years was 4.7% in the control group compared with 15.6% in the hypofractionated group.

In spite of this, the researchers conclude: “Our long-term results provide support for the use of accelerated, hypofractionated, whole-breast irradiation in selected women with node-negative breast cancer after breast conserving surgery.”

Whelan said the study's results will change cancer treatment practice not just in Canada, but throughout North America and around the world. He added that further research is now looking at even shorter, more intensive therapy. MedWire: Oncology, Breast cancer

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