Few women who were treated for breast cancer feel persistent fatigue a year later, an Australian study suggests.

Disabling fatigue is common after many cancer treatments, with some studies estimating up to half of women feeling that way for months after treatment ends.

Researchers in Australia set out to test how common cancer-related fatigue actually is among women with early-stage breast cancer who had surgery along with treatment such as radiation or chemotherapy.

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Breast cancer survivor Hastine Reese, 50, said exercising helped lift her mood after treatment. (David Goldman/Associated Press)

"The good news is that the vast majority of women who have undergone cancer treatment either never experience ongoing debilitating fatigue in the weeks and months after treatment ends or if they do, it passes relatively quickly," said Professor David Goldstein of the University of New South Wales in Sydney.

Cancer-related fatigue is common but people can be reassured that in most cases, it is not debilitating in the long-term, he added in a release.

For the study in April's issue of the Journal of Clinical Oncology, Goldstein and his colleagues followed 218 women for five years.

Tumour size a factor

The breast cancer patients were observed and questioned every three months for a year after treatment and then again at five years.

The researchers used a strict definition of confirmed fatigue that ruled out causes such as anemia or thyroid disease.

Investigators recorded both physical and psychological aspects, such as pain, sleep and mood.

An oncologist and in most cases a psychiatrist reviewed the persistent cases of fatigue.

Large tumour size was the only predictor of persistent cancer-related fatigue, the researchers said.

Exercise benefits

The rate for cancer-related fatigue fell steadily from 31 per cent at the end of treatment to 11 per cent at six months and six per cent at one year.

The small minority of women who experience ongoing fatigue need to be identified early so resources can directed to them, the study's authors concluded.

Exercise may be a key way of helping more cancer survivors to manage, they suggested.

New guidelines released this week by the American Cancer Society urge doctors to talk to cancer patients about eating right, exercising and slimming down if needed.

Hastine Reese, a breast cancer survivor, said she began to exercise because her husband pushed her to. Besides being good for her health, he thought it might help pull her out of the depression that followed her diagnosis and double-mastectomy.

"When you're first diagnosed with cancer, you go into a dark place," said Reese, as she finished a one-hour exercise class this week at DeKalb Medical Center in Decatur, Ga.

Exercise has helped her mood. "I'm coming into the light, and it's getting brighter and brighter," she said.

The study was funded by the Susan G. Komen Foundation and Ramaciotti Foundation.

With files from The Associated Press