A new article published in the Journal of Clinical Oncology shows that breast cancer survivors who quit smoking after their diagnosis had a 33 percent lower risk of death as a result of breast cancer than those who continued to smoke.

“Our study shows the consequences facing both active and former smokers with a history of breast cancer,” said first author Michael Passarelli, PhD, a cancer epidemiologist at the UCSF School of Medicine. “About one in ten breast cancer survivors smoke after their diagnosis. For them, these results should provide additional motivation to quit.”

The Collaborative Breast Cancer Study involved more than 20,600 women with breast cancer at 3 sites across the U.S. This is one of the largest studies of survival outcomes according to smoking habits in women with a history of breast cancer, and the first study to assess smoking habits both before and after diagnosis.

The 2014 Report of the Surgeon General on the health consequences of smoking suggested that there may be a causal relationship between breast cancer and smoking. Previous studies have also speculated that the risk of developing breast cancer in smokers might depend on when smoking started and for how long.

Approximately one in ten cancer patients continued to smoke following their diagnosis and they were more likely than people who had never smoked and former smokers to die of breast cancer, the researchers said. Those who quit smoking after diagnosis had lower mortality from breast cancer and respiratory cancer.

“Smoking cessation programs should be considered part of cancer therapy,” Passarelli said. “Recent policy statements from leading research and clinical organizations are now urging oncologists to be as aggressive in getting their patients to stop smoking as they are in treating the cancer.”

Read full article in the UCSF Media Release.