Breast Cancer Prevention Matters
It is estimated that there will be 246,660 new cases of breast cancer in the United States this year. This number represents an increase of 15,000 new cases in a two-year period. Unfortunately, breast cancer prevention outside of screening mammography has gotten little attention within the medical community, but the topic will become increasingly relevant as we face the predicted shortage of cancer specialists and the increasing societal burden of breast cancer.
According to cancer prevention experts, only 10% of cancers are attributed to genetic defects, while the other 90% are related to environment and lifestyle factors. Numerous studies have confirmed this to be true for breast cancer. Regular physical activity, reduced alcohol intake, weight management (especially after menopause) and healthy eating, have all been shown to reduce the incidence of the disease.
Regular exercise helps to balance hormones, improve immune function, and reduce stress and inflammation all of which reduce cancer risk. The American Cancer Society Prevention Study found that women who walked at least seven hours per week had 14% reduction in post-menopausal breast cancer compared with women who walked less than three hours a week. In addition, pre-menopausal breast cancer risk was reduced among women with high levels of activity during youth and adulthood.
Alcohol's association with cancer is well established. Alcohol increases the risk of cancer by producing free radicals that damage DNA, interrupting controlled cell division, and contributing to nutrient deficiencies that weaken immune function. There is a 7% increase in breast cancer risk for every 10 grams of alcohol consumed per day. (The average drink contains about 12-14 grams of alcohol.) The Nurses' Health Study found that women who drank moderately (consumed 3-6 drinks per week) had a 15% increased risk of breast cancer. Women who drank minimum of two drinks per day were 51% more likely to have breast cancer than non-drinkers.
Obesity increases the hormone burden directly associated with cancer. In addition, it alters inflammatory pathways in the body and interrupts healthy energy balance, both of which contribute to cancer risk. Results from the Nurses' Health Study showed that avoiding weight gain after menopause can decrease breast cancer risk by 12%. The study also revealed that postmenopausal women who lost 20 pounds and kept the weight off had a 50% reduction in breast cancer risk compared with women who maintained their weight after menopause. In addition, women who had steady weight gain from age 18 had an increased risk of breast cancer directly related to the amount of weight gained.
Over the last three decades, medical treatment of hormone (estrogen and progesterone) receptor-positive and growth factor (HER2) receptor-positive breast cancers has improved significantly and is now associated with reduced mortality rates. In comparison, triple-negative breast cancers those that are negative for estrogen, progesterone, or growth-factor receptors which account for about 20% of all breast cancers have fewer treatment options. There is growing evidence that an increased intake of fruits and vegetables is associated with a decreased risk of developing triple-negative breast cancer. In a study of a group of women it was observed that women with the highest blood levels of carotenoids (chemo preventive plant compounds from vegetables such as tomato) were less likely to develop triple negative breast cancer.
Behavior modification provides promising opportunities for cancer prevention. The first step in prevention behaviors is being aware of healthier behavior options. Breast cancer prevention matters and is possible with behavior modification and education.