Among Women at High Risk for Breast Cancer, Study Finds Smoking, Not Moderate Alcohol Use, Increases Risk of Common Cancers

Stephanie Land, PhD

A prospective study from the University of Pittsburgh followed over 13,000 women between the years 1992 and 1997, already at an increased risk for developing breast cancer, and analyzed risk of contracting common cancers based on baseline self-reporting data on smoking, alcohol use, and physical activity.

“Many people are not aware that smoking causes cancers other than lung cancer, so I do believe this study may raise awareness of the risks caused by smoking, especially for women who are already at high risk of breast cancer for other reasons,” lead author, Stephanie Land, PhD, of the University of Pittsburgh, told OncLive.

Study results showed a much higher risk of invasive breast cancer in smokers than in nonsmokers. Women who smoked more than 35 years, compared to women who never smoked, had a 60% higher risk of invasive breast cancer. Women who smoked less than 15 years had no increased risk of breast cancer.

“This study also indicates that women can reduce their risk of endometrial cancer through exercise. Our large, carefully controlled and monitored prospective study adds weight to observations that have been controversial, such as the impact of exercise on endometrial cancer, and the impact of smoking on breast cancer and colon cancer.”

As part of the National Surgical Adjuvant Breast and Bowel Project (NSABP) Breast Cancer Prevention Trial, this is the third study to report a strong association between smoking and breast cancer. It is the first study of its kind, however, to report an increased risk of cancer development in women already at a high risk of breast cancer.

The study also found that the incidence of colon cancer increased significantly among women with a long history of cigarette smoking. The results showed that women who smoked more than 35 years were four times more likely to develop colon cancer than those who smoked 15 to 35 years. Women who smoked more than one pack of cigarettes a day for 35 years or more were 30 times more likely to develop lung cancer when compared to women who never smoked.

Another poignant result from this study was that 54% of women who self-reported low physical activity or inactivity, had a 72% increased risk for developing endometrial cancer, but study results showed no reported significant differences in the risk of other cancers. Also, women who had between zero and one alcoholic drink actually reduced their risk for colon cancer by 65%. They did not, however, report any significant difference in the development of other common cancers.

During an ASCO press briefing on May 18, Land said, “This study is good news because although breast, lung, colon, and endometrial cancer cannot be prevented, it shows that healthy lifestyles can reduce one’s risk.”

Land SR, Christian N, Wickerham DL, Costantino JP, Ganz PA. Cigarette smoking, fitness, and alcohol use as predictors of cancer outcomes among women in the National Surgical Adjuvant Breast and Bowel Project (NSABP) Breast Cancer Prevention Trial (BCPT). J Clin Oncol. 2011. (suppl; abstract 1505)