Breast cancer survivors might be able to reduce their risk for contralateral breast cancer by making lifestyle modifications. A new study published online September 8 in the Journal of Clinical Oncology has found that obesity, alcohol use, and smoking all significantly increase the risk for second primary invasive contralateral breast cancer among breast cancer survivors.
Researchers from the Fred Hutchinson Cancer Research Center in Seattle, Washington, found that obese women had a 50% increased risk for contralateral breast cancer, and those who consumed 7 or more alcoholic drinks per week had a 90% increased risk. Survivors who currently smoked had a 120% increased risk of developing a second breast cancer.
The risk was particularly high in women who were current smokers and who consumed at least 1 alcoholic beverage a day. The authors found that this subgroup of women had a 7.2-fold (95% confidence interval [CI], 1.9 – 26.5) elevated risk for contralateral breast cancer.
An updated version of the American Institute for Cancer Research/World Cancer Research Fund’s report, Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective, reaffirmed that factors such as maintaining a healthy weight, exercising regularly, and limiting consumption of alcoholic beverages can reduce the risk of developing breast cancer.
What did this study look at?
Dr. Li and colleagues evaluated the effect of obesity, alcohol consumption, and smoking on risk for second primary invasive contralateral breast cancer among breast cancer survivors.
How many women, and what type of cancer?
The cohort consisted of 365 women who were diagnosed with an estrogen-receptor (ER)-positive first primary invasive breast cancer and a second primary contralateral invasive breast cancer, and 726 matched controls who were diagnosed with only an ER-positive first primary invasive breast cancer.
How did they assess lifestyle?
Information regarding obesity, alcohol use, and smoking was acquired from medical-record reviews and from interviews with the participants. The researchers then used conditional logistic regression to assess the association of these 3 factors and the risk for a second cancer.
What did they find?
They found that compared with women who had a body mass index (BMI) lower than 25.0 kg/m2, those with a BMI of 30.0 kg/m2 or above had a higher risk for contralateral breast cancer (odds ratio [OR], 1.4; 95% CI, 1.0 – 2.1).
The consumption of alcohol was also positively related to an increased risk for a second cancer (OR, 1.9; 95% CI, 1.1 – 3.2) when evaluated at both the first diagnosis of breast cancer and during the interval between first breast cancer diagnosis and reference date.
In similar fashion, current smokers had an elevated risk for contralateral breast cancer (OR, 2.2; 95% CI, 1.2 to 4.0) at first breast cancer diagnosis and at reference date, compared with women who had never smoked. The association between smoking and cancer risk did not vary by pack-years, the authors note. A small number of women were smokers at the time of their first diagnosis but quit by their reference date (14 patients and 29 control subjects), and this did not seem to influence the risk of developing a second breast cancer.
- Second primary contralateral breast cancer is an outcome of great concern for breast cancer survivors because these patients have a 2 to 6 times’ greater risk for the development of a contralateral breast cancer than women in the general population have for the development of a first breast cancer.
- Obesity, smoking, and alcohol consumption all positively influenced the risk for second primary contralateral breast cancer among survivors of invasive ER-positive breast cancer.
Li CI, Daling JR, Porter PL, Tang MT, Malone KE. Relationship Between Potentially Modifiable Lifestyle Factors and Risk of Second Primary Contralateral Breast Cancer Among Women Diagnosed With Estrogen Receptor-Positive Invasive Breast Cancer. J Clin Oncol. 2009 Sep 8. [Epub ahead of print] View Abstract