Submitted by Shelley Snodgrass, MD, Augusta Health Primary Care, Fishersville
Globally, Breast Cancer is the most frequently diagnosed malignancy, accounting for over a million cases
each year. It is the leading cause of cancer death in women worldwide. Breast Cancer is the most common female cancer and the second-leading cause of cancer death among women in the United States.
In 2015, the United States age-adjusted rate of new female breast cancer cases was 125 per 100,000 women. Of the 242,476 new cases reported in the US, 6,288 cases were in Virginia. 41,523 women died from breast cancer in 2015.1 Breast cancer incidence increases with age and is most frequently diagnosed among women aged 55-64, with the median age of death 68 years old.2
Risk Factors
Approximately one-half of newly diagnosed breast cancers can be explained by known risk factors, and an additional 10 percent are associated with a positive family history. Only 5 to 6 percent of all breast cancers are directly attributable to inheritance of a breast cancer susceptibility gene such as BRCA1, BRCA2, p53, ATM, and PTEN.3
Established high-risk factors include advancing age, female gender, and white race. Additional risk factors include postmenopausal obesity, perimenopausal weight gain and tall stature (>69 inches). Increased exposure to estrogen through high endogenous estrogen levels, elevated androgen (testosterone) levels, exogenous hormone exposure (postmenopausal estrogen-progesterone use), early menarche, late menopause, nulliparity (and lack of breast feeding), and increasing age at first pregnancy are associated with increased risk.
Personal and family history of breast cancer (risk is increased nearly two-fold with one first degree relative, and three-fold with 2 first degree relatives regardless of the age at diagnosis), or prior breast biopsy with atypical hyperplasia or lobular carcinoma in situ are associated with increased risk. Family history of ovarian cancer, or other hereditary breast or ovarian syndrome associated cancers (prostate, pancreas) increase breast cancer risk.3,4
Exposure to therapeutic ionizing radiation, especially between the ages of 10 to 14 (and up to age 45) increases breast cancer risk.3
Regular physical exercise appears to provide modest protection against breast cancer. A diet rich in fruits and vegetables, fish, and olive oil (Mediterranean diet) may result in a lower risk of breast cancer. The influence of dietary fat and red meat is not clear.3
Risk Assessment
There are several validated risk assessment tools available, including the Gail, BRCAPRO, Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm, International Breast Cancer Intervention Studies (IBIS, also known as Tyrer–Cuzick), or the Claus model. One of the most widely accepted tools is the Gail Model, which is available online at http://www.cancer.gov/bcrisktool. This brief tool calculates both a 5-year and lifetime (until age 90) risk prediction which can be used to guide shared decision making. It is of limited use in some women, including those younger than 35 years, those with a family history of breast cancer in paternal family members or in second-degree or more distantly related family members, those with family histories of non-breast cancer (ovarian and prostate) known to be associated with genetic mutations, and high-risk lesions on biopsy other than atypical hyperplasia (such as lobular carcinoma in situ).4 For these patients, a more comprehensive risk assessment tool should be utilized.
Screening Recommendations
Screening recommendations and guidelines have been established by several groups, including the American College of Obstetricians and Gynecologists (ACOG) and the US Preventive Services Task Force (USPSTF). Additional guidelines are available from the American Cancer Society, the National Comprehensive Cancer Network, and several others. Recommendations vary between the balance of risks and benefits of screening, what age to start and stop screening, and how frequently to perform screening. Shared decision making, taking into account the risks and benefits of screening, individual risk factors, and the patient’s personal goals and preferences should be used to establish an appropriate screening schedule.4 Several of the most commonly referenced screening guidelines are in the table that follows. A summary of additional society guidelines can be found at https://www.cdc.gov/cancer/breast/pdf/BreastCancerScreeningGuidelines.pdf.
Benefits and Harms of Screening
Regular screening mammography starting at age 40 years reduces breast cancer mortality in average-risk women, with the benefit increasing with advancing age. Screening, however, also exposes women to potential harms, such as callbacks, anxiety, discomfort or pain, false-positive results, over diagnosis and overtreatment.
Methods of Screening
Breast self-examination is not recommended in average-risk women because there is a risk of harm from false-positive test results and a lack of evidence of benefit. Average-risk women should be counseled about breast self-awareness and encouraged to notify their health care provider if they experience a change.4 Guidelines on the utility of clinical breast exams for average-risk women vary between the societies, and so the decision to include clinical breast exams should be a part of the shared decision making process.
Screening mammography remains the preferred method for breast cancer screening for average-risk women. Digital tomography is an emerging technology that has been shown to decrease the number of callbacks, but is not recommended for routine screening at this time.2
Approximately 75% of eligible patients complete routine screening mammography. Lower income, uninsured or underinsured, and certain minority groups tend to have lower screening rates. There are resources available to help provide breast cancer screening to uninsured patients through the CDC National Breast and Cervical Cancer Early Detection Program at https://www.cdc.gov/cancer/nbccedp/. Virginia’s program, Every Women’s Life, has been CDC funded since 1993. Instructions and application forms can be obtained by contacting:
Every Woman’s Life Virginia Department of Health
109 Governor Street, 8th Floor
Richmond, VA 23219
1 (866) 395-4968 (in state)
(804) 864-8204
Fax: (804) 864-7763
http://www.vdh.virginia.gov/every-womans-life/
Citations:
1U.S. Cancer Statistics Working Group. U.S. Cancer Statistics Data Visualizations Tool, based on November 2017 submission data (1999-2015): U.S. Department of Health and Human Services, Centers for Disease Control and Prevention and National Cancer Institute; http://www.cdc.gov/cancer/dataviz , June 2018.
2Final Recommendation Statement: Breast Cancer: Screening. U.S. Preventive Services Task Force. November 2016. Accessed at
https://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/breast-cancer-screening
3Factors that Modify Breast Cancer Risk. Up-to-Date Article updated 5/24/18 and current through September 2018.
4ACOG Revises Breast Cancer Screening Guidance: Ob-Gyns Promote Shared Decision Making. American College of Obstetricians and Gynecologists. June 27, 2017. Accessed athttps://www.acog.org/About-ACOG/News-Room/News-Releases/2017/ACOG-Revises-Breast-Cancer-Screening-Guidance–ObGyns-Promote-Shared-Decision-Making