Among women who have been treated for breast cancer, those who stick to a healthy diet and are moderately active seem to live longer, results of a new study indicate. A good diet alone or exercise alone doesn't have the same benefit.

"It looks like if you get your physical activity going and get your fruits and vegetables in you can reduce your risk (of dying) significantly," study co-author Dr. John Pierce told Reuters Health.

Several studies have shown that diet and exercise may each contribute to breast cancer survival, but little research has looked at the effect of both diet and exercise together. Pierce, director of the Cancer Prevention and Control Program at the Moores UCSD Cancer Center, in La Jolla, California, and his team looked at the combined effects of diet and exercise for breast cancer survivors.

They studied 1,490 women who had been treated for breast cancer 2 years earlier, on average.

Overall, only 30 percent of these women maintained the healthiest type of lifestyle, including eating five or more servings of fruits and vegetables daily and engaging in physical activity equivalent to a half-hour of brisk walking six days a week.

These women had a 44 percent lower risk of dying within a 10-year period than did their peers, Pierce and his team report in the Journal of Clinical Oncology.

What's more, this lower risk of death remained true regardless of whether the women were obese, study findings indicate. The effect of physical activity and diet was "so strong it wiped out the body mass index effect," Pierce said. However, obese women were less likely than nonobese women to report such healthy habits.

A similarly reduced risk of death was not apparent among non-physically active women who consumed the highest amounts of fruits and vegetables or among physically active women who did not eat at least five servings of fruits and vegetables a day, the investigators note.

"Doing each one alone didn't do it," Pierce said. "There was no benefit from each one alone, but there was a benefit from both together."