Less may be more when it comes to radiation treatment for breast cancer.

New Canadian research shows that an intense three-week course of radiation that's already in use in many cancer centres across Canada is just as effective and safe over the long term as the previously-standard five weeks of treatment.

Lead researcher Dr. Tim Whelan, a professor of oncology at McMaster University in Hamilton, says shorter radiation treatment times offer a number of benefits, not only in terms of savings to the health care system, but to women themselves.

Women diagnosed with breast cancer usually have to undergo surgery, often followed by chemotherapy or anti-hormonal therapy and then radiation. Whelan says the shorter radiation treatment time should make the difficult treatments a little bit more palatable to women.

"Treatments are so long for some women that they try to avoid radiation. They may even consider a mastectomy to avoid radiation after breast-conserving surgery," he told CTV's Canada AM Thursday.

"So to be able to reduce radiation therapies makes treatment much more attractive to women."

Whelan's research, published in the New England Journal of Medicine, involved 1,234 women with invasive, node-negative breast cancer who had a lumpectomy. The surgery involves removing the cancerous tumour as well as a small amount of normal tissue around it.

After surgery, some of the women had standard radiation treatment over a 35-day period, while the rest had the accelerated treatment over 22 days.

The shorter schedule involved a gradually more intense dose of radiation than the standard therapy, Whalen explained.

"With the shorter treatment, it's a little more intensive each day, but the overall dose is a little bit less. So in fact, women are actually receiving less radiation, which could also have additional benefits for women, long-term," he explained.

The women's health was monitored over 10 years. The researchers found that the risk for local recurrence of the cancer over that time was about the same in both groups: 6.7 per cent among the women given the standard treatment, and 6.2 per cent among those given the briefer treatment.

The probability of survival at the 10-year mark was also similar: 84.4 per cent for the standard group and 84.6 per cent for the accelerated group.

Cosmetic outcomes were termed "good" or "excellent" in about 71 per cent of the women in the standard-treatment group and 70 per cent of the accelerated-treatment group.

"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 and his research conclude in their study.

"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."

Whelan said further research is now looking at even shorter, more intensive therapy, involving twice-a-day radiation doses given over five days.