Risk Factors for Developing Breast Cancer
There are multiple risk factors for breast cancer including age (90% of breast cancers occur in women over age 45), genetic mutations, previous breast cancer, family history, dense breast tissue, reproductive and menstrual history (women who had their first menstrual period before age 12 or who went through menopause after age 55 have an increased risk of breast cancer as well as women who had their first full term pregnancy after age 30 or who never had a full term pregnancy are also at increased risk) and previous radiation to the chest. None of these can be changed by lifestyle. There are a number of risk factors associated with lifestyle including body weight, activity level and alcohol use.
Body Weight and Weight Gain
Body weight and weight gain appear to be important risk factors for the development of 13 different cancers including postmenopausal breast cancer. Studies show that weight gain after the age of 20 (termed adult weight gain) is associated with an increased risk of postmenopausal breast cancer with an estimated increased risk of 12% for every increase in BMI of 5 points. What may be even more important than actual BMI is where the weight is carried. Those women who have extra fat in their belly appear to have a greater risk of postmenopausal breast cancer than those who carry extra weight in the thighs and hips. Another important factor in postmenopausal breast cancer risk is a patient’s metabolic health. Those with insulin resistance (regardless of weight) have an increased risk of breast cancer. The big question is: does improving metabolic health and losing weight decrease the risk of postmenopausal breast cancer? The answer appears to be yes. Weight loss as little as 5% of a person’s body weight can result in improvement of metabolic profile (insulin sensitivity) and reduction in breast cancer risk.
The use of alcohol is the most consistent dietary component associated with breast cancer. There appears to be a dose dependent relationship between alcohol consumption and risk of breast cancer (meaning the more alcohol you drink the higher your risk of breast cancer). An increased risk of breast cancer has been measured at as little as 1 drink per day.
Regular exercise has been shown to reduce the risk of breast cancer and improve insulin sensitivity (the ability of your cells to use insulin). Regular exercise should be included in a lifestyle program to reduce cancer risk.
Finally, healthy sleep habits can improve insulin sensitivity and reduce your risk of breast cancer. Rotating shift work with sleep pattern disruption increases a woman’s risk of breast cancer, probably through disruption of insulin signaling.
It has been estimated that 30% of breast cancer cases could be avoided with the implementation of an optimal breast cancer risk reduction strategy, including eliminating added sugar, fast and processed foods and eating a whole foods diet which includes 5-7 servings of fruits and vegetables daily, tree nuts, olive oil, whole grains, legumes, pasture raised meats and wild caught fish, maintaining a healthy weight and not gaining weight in adulthood, exercising daily and getting 7-9 hours of restful sleep nightly. Enjoying time in nature, nurturing positive social relationships and being kind and compassionate to yourself can also improve your health and well-being.
2) Andrew Weil Center for Integrative Medicine – University of Arizona.
3) Sanchez-Jimenez F, et al. Obesity and Breast Cancer:Role of Leptin. Frontiers in Oncology. 2019; 9:1-12.