Breast Cancer Risk and Prevention

There following are generally accepted risk factor for developing breast cancer, several of which are modifiable through lifestyle change.   

RISK

• Gender - Women in general are more at risk because our breast cells are constantly exposed to the effects of hormones, estrogen and progesterone. Men comprise less than 1% of breast cancer cases.

• Race - Caucasian women have the highest risk overall. African American women are at greater risk before age 35 over Caucasian women. More African American women have aggressive tumors and are more likely to die from breast cancer at any age. Latino, and Asian, and Native American Indian women are at lower risk.

• Hormonal Replacement Therapy -  A large study from the Women's Health Initiative revealed a 26% increased risk from  HRT, especially combined estrogen and progesterone. It   was also found that because women on combined HRT often cause difficulties in reading mammograms, their chances of dying from breast cancer also increased due to later detection The results of using estrogen alone were found to be uncertain (2).

• Oral Contraceptive Use - Studies have reported that the use of oral contraceptives increase risk slightly. Women who stopped using them more than ten years ago, however, do not have an increased risk (4,5).

• Abnormal Biopsy - Women with a history of abnormal biopsies diagnosing hyperplasia, specifically atypical hyperplasia, have a moderate to significant increase in risk. The confirmation of radial scars through biopsy also increases risk.

• Breast Tissue Density - Denser breast tissue is associated with an increased risk.

• Personal History of Breast Cancer - Women who have had breast cancer in one breast are at increased risk for developing cancer in the other breast.

• Family History - Those with close relatives who have breast and/or ovarian cancer and those who have inherited the breast cancer genes have increased risk. This is examined in greater detail in the ACS Breast Cancer Guidelines and Statistics.

• Menstrual History - Women who have had their first period before age 12 are at slightly higher risk. This is thought to be a result of the influence of menstruation on hormone levels.

• Menopause - Women who go through menopause after age 55 are at a slightly higher risk. 

• Pregnancy -  Women who have never had children and those having their first child after 30 are at slightly higher risk. Having more than one pregnancy also lowers risk.

• Breast-Feeding - Some studies have suggested that breast cancer risk is slightly reduced for cancer occurring before menopause (4). Breast-feeding for longer durations lowered risk even more. Other studies found no relationship.

• Radiation - Women have been exposed to high doses of radiation during childhood and adolescence have increased risk. This includes radiation from atomic bomb blasts and radiation therapy to the chest, as with Hodgekins disease and tuberculosis.

• Alcohol Consumption - Research shows that drinking 2-5 drinks per day increases risk by 1.5 times than non-drinkers. This is thought to be due to interference of alcohol in vitamin absorption, possibly A, and the alcohol's ability to interfere with estrogen metabolism in the liver. Minimal consumption (one drink or less) of alcohol has not been found to increase risk.

• Exercise - Regular exercise is generally associated with lower risk. In one study from the Women's Health Initiative, briskly walking as little as 2.5 hours per week cut breast cancer risk by almost 20% (8).

• Obesity - Weight gain increased risk for post-menopausal women (6). This is generally thought to be due to the resulting increased estrogen levels after menopause. Body shape also plays a role; women carrying their extra weight around their waist (versus the hips and thighs) are at greater risk. 

• Diet - Research has determined that diets low in vitamin A and caratinoids are associated with a greater risk. High concentrations of these and antioxidants are found in fruits and vegetables. Consuming a modest to high concentration of these nutrients, lowered risk in pre-menopausal women by 25 to 35% (11). To date, studies related to dietary intake, however,  have proven to be controversial in recommending a diet low in saturated fats. Nonetheless, most studies have found that breast cancer rates are lower in countries where a diet low in total fat, polyunsaturated fats, and saturated fats, is consumed. A large-scale dietary study in Sweden found that monounsaturated fats decreased breast cancer risk by 45% and polyunsaturated fats increased risk by 60%.

• Age - Breast cancer risk generally increases with age. The 1 in 7.56 chance that a woman will develop invasive cancer in her lifetime is based on a life span of 85 years.

PREVENTION

It should be noted that new studies come out all the time, and that breast cancer risk and prevention factors are a controversial subject. Some of these risk factors by themselves only slightly increase breast cancer risk, while others show mixed results, therefore warranting further study. For example, active smoking and second-hand smoke have not been directly linked to breast cancer but, have been found to increase the incidence of breast cancer in women when solely compared to those not exposed to second-hand smoke (10). It is also widely accepted that refraining from smoking is beneficial to one's health and offers a protective benefit from other cancers.

Dietary and environmental risk factors continue to be studied. It appears that maintaining a healthy lifestyle, both physically and mentally is advantageous. Excluding non-modifiable risk factors, many studies show that minimal or no use of  combined HRT, oral contraception and alcohol, while maintaining normal weight, adhering to a healthy low-fat diet with a high concentration of fruits and vegetables, and regular exercise can substantially lower risk. A common sense approach is necessary to address risk factors, and those in question should be discussed with your health care provider. This information is in no way meant to diagnose, treat, or cure disease.

Sources:

1. ACS - Breast Cancer Guidelines and Statistics, 2005-2006.

2. Rossouw JE, Anderson GL, Prentice RI, et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial. JAMA. July 17 2002;228(3):321-333.

3. Collaborative Group on Hormonal Factors in Breast Cancer. Breast Cancer and breastfeeding collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries,     including 50,302 women with breast cancer and 96,973 women without the disease. Lancet. July 20 2002;360(9328):187-195.

4. Kumle M, Weiderpass E, Braaten T Perrson I, Adami HO, Lund E. Use of oral contraceptives and breast cancer risk: The Norweigian-Swedish Women's Lifestyle and Health Cohort Study. Cancer Epidemiol Biomarkers Prev. Nov 2002; 1(11):1375-1381.

5. Gram IT, Funkhouser E, Nordgard L, Tabar L, Ursin G. Oral contraceptive use and mammographic patterns. Eur J Cancer Prev. Jun 2002;11(3);265-270.

6. International Agency for Cancer Research (IARC). IARC Handbook of Cancer Prevention. Volume 6: Weight control and physical activity. Lyon: IARC Press; 2002.

7. Bianchini F Kaas R, Vainio H. Weight control and physical activity in cancer prevention. Obes Rev. Feb 2002;3(1):5-8.

8. McTiernan A, Kooperberg C, White E, et al. Recreational physical activity and the risk of breast cancer in postmenopausal women: the Women's Health Initiative Cohort Study. JAMA.    Sep 10 2003;290(10):1331-1336.

9. Fentiman IS. Fixed and modifiable risk factors for breast cancer. Int J Clin Pract. Oct 2001;55(8):527-530.

10. Hamajima N, Hirose K, Tajima K et al. Alcohol, tobacco and breast cancer - collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease. Br J Cancer. Nov 18 2002;87(11):1234-1245.

11. Tamimi RM, Hankinson SE, Campos H, et al. Plasma Carotinoids, Retinol and Tocopherols and Risk of Breast Cancer. Am J Epidemiol. 2005 Jan 15;161(2):153-160.