Being obese, drinking seven or more alcoholic drinks a week, and smoking, all significantly increase the risk that breast cancer survivors will see their cancer return, a new study confirms.
Researchers from the Fred Hutchinson Cancer Research Center in Seattle came to their conclusions after studying more than 1,000 Seattle-area breast cancer survivors.
Their study, published in the online edition of the Journal of Clinical Oncology, focused on women with estrogen receptor-positive (ER-positive) breast cancer, the most common form of breast cancer, first diagnosed between the ages of 40 and 79.
The study participants included 726 women who had had one breast cancer, as well as 365 women who had developed a second breast cancer in their opposite breast.
The women were interviewed about their smoking and drinking habits, and their BMI (body mass index) was noted in their medical records.
The researchers found that the odds of developing a second breast cancer were greater for obese women, for women who drank at least seven drinks per week, and for current smokers.
- Obese women had a 50 per cent increased risk of developing a second breast cancer
- Women who had at least one alcoholic drink per day had a 90 per cent increased risk
- Women who were current smokers had a 120 per cent increased risk.
Both obesity and alcohol can lead to increased levels of circulating estrogen, which can fuel breast cancer growth. Smoking hasn't been firmly established as a breast cancer risk, but it is well known that cigarette smoke contains carcinogens.
Study author Dr. Christopher I. Li says it's estimated that women who have survived breast cancer are at two to six times greater risk of developing a second cancer compared to women in the general population. He says his study offers women three solid ways to reduce their risk of a second cancer:
"Stay at a normal weight, don't smoke and drink in moderation," he said.
"We know that lifestyle factors such as obesity, smoking and heavy alcohol consumption are linked with a number of life-threatening diseases in addition to cancer, and so reducing or eliminating these factors could have the added benefit of reducing a survivor's risk of developing a second breast cancer."
The National Cancer Institute in the U.S. funded the research.
