Researchers recently tracked breast cancer survival among more than 1,200 women diagnosed with breast cancer between 1990 and 1992.
The women were 20-54 years old at the time of their diagnosis (average age: 42). They recalled their physical activity level at age 13, 20, and the year before breast cancer diagnosis.
Most were diagnosed with breast cancer in the disease's early stage, when it hadn't spread beyond the breast or nearby area.
Most women were still alive eight to 10 years after diagnosis. But 290 died during that time.
Those who were overweight or obese at the time of breast cancer diagnosis -- and were also highly physically active in the year before -- had a survival rate 30% better than their inactive peers.
No such benefit was seen for women who weren't overweight or obese. But there was no downside to exercise for any of the women, in terms of breast cancer survival.
7 Questions, 7 Answers
Page Abrahamson, PhD, was among the researchers who worked on the study, published in Cancer's Oct. 15 edition.
Abrahamson worked on the study while at the University of North Carolina, Chapel Hill. She is now on staff at Seattle's Fred Hutchinson Cancer Center.
In an interview via email, Abrahamson discussed the study and its findings. She stresses that it's too soon to make recommendations about exercise and breast cancer survival.
Q. What is the main thing you want people to know about the study and its findings?
A. Our study explored whether exercise before a breast cancer diagnosis influenced a woman's prognosis after being diagnosed with the disease.
We found a beneficial effect on survival for exercise undertaken in the year before diagnosis, particularly among women who were overweight or obese near the time they were diagnosed with breast cancer.
Q. What do you see as the study's 'take-home' message?
A. This is one of the few studies to look at the association between exercise and breast cancer survival.
Our study found that exercise prior to diagnosis may beneficially impact the odds of surviving after a diagnosis.
Q. Does the data shed any insight on the types of physical activity that the women did (aerobic exercise, weight training, walking, gardening, etc.)?
A. Unfortunately our study is not equipped to answer that question.
While we asked about a variety of activities, we did not assess a comprehensive list of various physical activities in enough detail to look at the effects of exercise by type.
Q. What would you want women to know about exercise vs. physical activity (is a challenging workout better than a casual stroll), or is it too early to get into that level of detail?
A. It is too early to make that type of recommendation to women. Very few studies have looked at this topic.
While we were able to look for a more general association between exercise and survival, future studies may be able to assess more thoroughly the impact of specific types of fitness and exercise patterns.
Q. Is there anything you would want to say about older women, exercise, and breast cancer? Or is it too early to say?
A. This study only looked at younger (and mostly premenopausal at the time of diagnosis) women.
Q. How confident are you that the women's recall of their past physical activity was reasonably accurate?
A. As with any observational epidemiologic study of this type, the accuracy of recalled behaviors is always a concern.
However, we were able to test different scenarios of incorrect recall and found that the beneficial effect of exercise on survival was stronger assuming most of these scenarios.
Q. What are the next steps you would like to see taken in researching this topic
A. Because few studies have investigated the impact of physical activity on breast cancer survival, more research in this area is warranted.
In particular, it is important to study the effects of exercise at different periods across the lifespan as well as the effect of specific types of activity. For breast cancer patients, this includes studying the effects of exercise undertaken following their diagnosis.
If future research confirms that physical activity improves survival among women with breast cancer, programs and policies to promote such activity for this purpose may be adopted.
SOURCES: Abrahamson, P. Cancer, Oct. 15, 2006. Page Abrahamson, PhD, Fred Hutchinson Cancer Center, interviewed via email. News release, John Wiley & Sons, Inc.
By Miranda Hitti
Reviewed by Louise Chang