The study by researchers at Fred Hutchinson Cancer Research Center has been published online Sept. 8 in the Journal of Clinical Oncology.
"We found that obese women had a 50 percent increased risk, women who consumed at least one alcoholic drink per day had a 90 percent increased risk, and women who were current smokers had a 120 percent increased risk of developing a second breast cancer," said lead author Christopher I. Li, M.D., Ph.D., an associate member of the Public Health Sciences Division at the Hutchinson Center.
The research suggests that current smokers who imbibe at least seven drinks a week may be at particularly high risk of second breast cancer.
"Our study results afford breast cancer survivors three ways to potentially reduce their risk of second cancers: Stay at a normal weight, don't smoke and drink in moderation," he said.
Both obesity and alcohol use are associated with increased levels of circulating estrogen, and this is thought to be the primary means through which they confer an increased risk of breast cancer, since estrogen can fuel breast cancer growth. The link between smoking and breast cancer may be attributed to carcinogens in tobacco smoke.
To reach the conclusion, Li and colleagues assessed body mass index, alcohol use and smoking status in 365 women who were diagnosed with both a first and a second breast cancer, and compared them to 726 matched controls diagnosed with only a first breast cancer.
Obesity, alcohol use and smoking data were collected from medical record reviews and participant interviews. The study participants, all from the Seattle/Puget Sound region, were first diagnosed with breast cancer between the ages of 40 and 79. (ANI)