Women diagnosed with breast cancer who continue to smoke cigarettes are less likely to survive than those who never smoked or who quit, acccording to a new study.
"Women who quit smoking at the time of their diagnosis do better, they have better outcomes than women who continue to smoke after the diagnosis," said study leader Michael Passarelli, a cancer epidemiologist at the University of California, San Francisco.
The smokers also had a higher risk of dying from respiratory cancers or heart disease and strokes, the researchers have found.
The study was published in the Journal of Clinical Oncology.
The researchers looked at the data from more than 20,000 women. The women were between the ages of 20 and 79, and nearly all were white. All had been diagnosed with breast cancer between 1988 and 2008.
The researchers looked at the data from more than 20,000 women. The women were between the ages of 20 and 79, and nearly all were white. All had been diagnosed with breast cancer between 1988 and 2008.
Six years after the diagnosis, the researchers contacted more than 4,500 of the women, asking about their smoking status. During the follow-up of about 12 years, almost 6,800 women died, including about 2,900 deaths due to breast cancer, the findings showed.
Active smokers who were smoking a year before the diagnosis were 25 percent more likely than never smokers to die from breast cancer. They were also more likely to die from respiratory cancer, respiratory disease or from cardiovascular disease, according to the report.
The researchers compared the 10 per cent of women who kept smoking after diagnosis to the never smokers and found they were 72 per cent more likely to die of breast cancer.
Next, the investigators compared those who quit smoking after being diagnosed with those who continued to smoke. Those who quit were 33 per cent less likely to die of breast cancer during the follow-up period, although the researchers said the difference was not statistically significant.
Women who quit smoking after their breast cancer diagnosis were 60 per cent less likely than those who kept smoking to die of respiratory cancer, the research showed.
At the study start, 20 per cent of the women were current smokers. That went down to 10 per cent at the six-year follow-up, according to the report.
Other studies have looked at the risk of death from cancer in smokers, but surveying the patients six years later, as this team did, is not commonly done, Passarelli said.
"Oncologists should be very aggressive about getting their patients to stop smoking," Passarelli said. Exactly why smoking lowers survival odds wasn't looked at in the new study, but he said that smokers may have more treatment-related complications, among other factors. Smoking could also affect the tumor growth, he said.
