Breast-cancer survivors have a 120-percent greater risk of suffering a second breast cancer if they continue to smoke, while daily drinkers face a 90-percent increase in risk of cancer returning, according to researchers at the Fred Hutchinson Cancer Research Center in Seattle.

The Seattle Post-Intelligencer reported Sept. 8 that obesity also raises the risk of a second incidence of breast cancer by 50 percent. "Many of the risk factors for breast cancer are not modifiable, such as family history of the disease or pregnancy history, but here we find that three potentially modifiable risk factors influence risk of second breast cancer," said researcher Christopher Li.

Smoking is not normally associated with breast cancer, "so it is somewhat surprising that we found it to be so strongly related to the risk of a second breast cancer," noted Li.

Overall, women who have had breast cancer are two to six times more likely to have a second cancer than other women.

The study was published online in the Journal of Clinical Oncology.