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How Lifestyle Factors Can Affect Breast Cancer

December 11, 2009

Written By Yarissa Reyes

Two new studies presented during the San Antonio Breast Cancer Symposium reveal a further connection between lifestyle factors and breast cancer. Both studies were presented during a general session on Thursday, December 10.

Effect of Obesity on Outcomes after Early Breast Cancer

The first study, " Effect of Obesity on Prognosis after Early Breast Cancer," was presented by Marianne Ewertz, MD, professor in the Department of Oncology at Odense University Hospital in Denmark. This study concluded that women with breast cancer with a high body mass index (BMI), a measure of weight in relation to height, have a poorer cancer outcomes later in life. Specifically, their treatment effect does not last as long and their risk of mortality increases.

Dr. Ewertz and colleagues examined how obesity affects the risk of breast cancer recurrence and mortality in relation to adjuvant treatment. Using the Danish Breast Cancer Cooperative Group database, they evaluated health information such as status at diagnosis, tumor size, malignancy grade, number of lymph nodes removed, estrogen receptor status, treatment regimen, etc. from almost 54,000 women. Dr. Ewertz and colleagues were able to calculate BMI for 35 percent of the women whose information about height and weight was available. A healthy, normal BMI score is between 20 and 25. A score below the normal range indicates underweight, and a score above indicates overweight.

After 30 years of follow-up (from 1977 through 2006), the researchers found that women with higher BMIs were older and had more advanced disease at diagnosis compared with those who had a BMI within the normal range. The risk of distant metastases increased the higher the BMI. However, BMI played no role in loco-regional recurrence.

Women with a high BMI had an increased risk of mortality from breast cancer, a finding that remained constant over the study period. Adjuvant treatment also seemed to lose its effect more rapidly in obese patients, according to Dr. Ewertz.

"Overall, women should make an effort to keep their BMI less than 25," said Dr. Ewertz. "Those who have a high BMI should be encouraged to participate in mammography screening programs for prevention efforts."

Alcohol Consumption and Breast Cancer Recurrence and Survival among Women with Early-Stage Breast Cancer

The second study, " Alcohol Consumption and Breast Cancer Recurrence and Survival among Women with Early-Stage Breast Cancer", was presented by Marilyn L. Kwan, PhD, staff scientist in the Division of Research at Kaiser Permanente. The study concluded that drinking three to four alcoholic drinks or more per week might be related to an increased risk of breast cancer recurrence, particularly among postmenopausal and heavier women, regardless of other prognostic factors.

Dr. Kwan and colleagues examined the effects of alcohol on cancer recurrence and mortality in the Life After Cancer Epidemiology (LACE) Study. LACE is a study of 1,897 women diagnosed with early-stage, invasive breast cancer between 1997 and 2000. The researchers recruited participants from the Kaiser Permanente Northern California Cancer Registry.

Information on wine, beer and liquor consumption was documented in a questionnaire.

Each year, participants also filled out information on health outcomes, including recurrence of breast cancer, which was then verified by their medical records.

After eight years of follow-up, Dr. Kwan and colleagues found 349 breast cancer recurrences and 332 deaths. Among drinkers (50 percent of the study population), wine was the most popular choice of alcohol (90 percent), followed by liquor (43 percent) then beer (36 percent). Increased risk of cancer recurrence was most predominant among those who consumed two or more glasses of wine per day.

The increased risk of recurrence appeared to be greater among participants who were postmenopausal and overweight or obese, regardless of type of alcohol.

Alcohol consumption was not associated with overall mortality.

Based on these findings, Dr. Kwan suggested, "women previously diagnosed with breast cancer should consider limiting their consumption of alcohol to less than three drinks per week, especially women who are postmenopausal and overweight or obese."