By: Jaivdhya Dasarathy MD, FAAFP
Reprinted from the summer 2019 issue of The Ohio Family Physician.
I have a 40-year-old woman presenting to my office for a physical and she asks, “Do I need a mammogram?”
- Annual screening at ages 40 to 84 years
- Screening annually at ages 45 to 54 years, then biennially at ages 55 to 79 years
- Biennial screening at ages 50 to 74 years.
With that in mind, let’s consider the following questions:
What Age Should the Screening Mammogram Start?
There is disagreement between different organizations about how early a woman with an average risk of breast cancer should start getting a mammogram. In 2016, the U.S Preventive Service Task Force (USPSTF) revised its guidelines and reiterated its recommendation that women between the ages of 50-74 should get a screening mammogram every two years and consult their doctor about their mammogram if they are < 50 years1.
The American Cancer Society (ACS) changed its guideline in 2015, recommending an annual mammogram from ages of 45-54 and a mammogram every 2 years from the age 55 and up2.
On the other hand, the American College of Obstetrics and Gynecology (ACOG), the American Medical Association, the National Cancer Institute, and the American College of Radiology (ACR) recommend getting an annual mammogram for women over 403.
Most of these organizations agree on not recommending a mammogram over the age of 75. The disagreement between the organizations considers all factors such as cost, over-diagnosis, anxiety of getting a mammogram, false positive results, unnecessary biopsies, and subsequent over-treatment. However, in a recent survey about getting a screening mammogram, 81% of physicians (861/1,665) recommended a mammogram between the ages of 40-444. Gynecologists are more likely to recommend mammograms than primary care physicians.
A mammogram is a screening procedure that has the potential to detect early breast cancer and it has risks and benefits like any other procedure. Women’s decisions about having a mammogram depend on age, breast density, family history of breast cancer, history of previous breast lump, and personal beliefs about the harms.
Do Mammograms Save Women?
Breast cancer is common in the United States and other developed countries, with approximately 1 in 8 women being diagnosed with breast cancer during their lifetime. Eighty percent of breast cancers diagnosed have no family history of breast cancer. One out of 64 women around the age of 40 is diagnosed with breast cancer. One-third of breast cancer deaths are attributed to women in their 40s, since cancer tends to be more aggressive in younger women.
The main benefits of a mammogram are reduction of breast cancer related death. Relative reductions vary from about 15 to 25% in randomized trials to more recent estimates of 13 to 17% in meta-analyses of observational studies with 15% for women in their 40s and 32% for women in their 60s5. Cancer Intervention and Surveillance Modeling Network (CISNET) models demonstrate that the greatest mortality reduction is achieved with annual screening of women starting at age 406. However, decreasing the number of breast cancer deaths alone cannot be the only criteria for any screening program. The harms of mammography screening, such as higher rate of false positive results, unnecessary biopsies, and over diagnosis, must be considered. Based on recent estimates from the United States, the relative amount of over diagnosis (including ductal carcinoma in situ and invasive cancer) is 31%5. The likelihood that a woman with an average risk will experience harm from the screening is higher than the likelihood that she will benefit; however, different patients will value these harms and benefits differently.
What Kinds of Risks Help Me Decide?
Patients who are at a high risk of breast cancer include: early menarche, late menopause, no children, older age at first birth (>30 years), obesity, alcohol and lack of exercise, family history of breast cancer, genetic mutations (BRCA 1/2 mutation), previous radiation to the breast, long term use of hormone replacement therapy, and dense breast tissue7. Seventy-five percent of women with breast cancer have no identifiable risk factors.
Higher mammography density is associated with increased breast cancer risk. A large population-based study showed a positive correlation between age at menarche and breast density and negative correlation between late adolescent body mass index and dense breast8.
Alcohol, weight, physical exercise, hormone replacement, and oral contraceptive pill are modifiable risk factors for breast cancer.
Although most breast cancers have no symptoms at presentation, one in 10 women with palpable breast abnormality or an abnormal mammogram will have breast cancer.
Common breast abnormalities include: palpable mass, nipple discharge, and breast pain. Approximately 10% of breast masses result in breast cancer9. All palpable abnormalities first need an ultrasound followed by a diagnostic mammogram if the patient is over 30. Nipple discharge requires evaluation with cytology with or without a mammogram. Breast pain can be diffuse or focal. Diffuse pain does not need any imaging; focal pain might require radiographic imaging.
How Frequently Should a Mammogram Be Done, Annually or Biennially? Which is Better?
Average doubling time for breast cancer is about one year. Premenopausal women diagnosed with breast cancer following a biennial screening mammogram were more likely to have bigger, more advanced tumors than women screened annually, while postmenopausal women not using hormone therapy had a similar proportion of tumors with less favorable prognostic characteristics regardless of whether their screening mammogram was biennial or annual10. Even though with less frequent mammography, tumors will be bigger and have a slightly advanced stage, biennial screening would be acceptable for post-menopausal women due to the nature of a slow growing and less aggressive tumor. Therefore, the USPSTF recommends screening average risk women biennially from ages 50-75 and the ACS recommends the same starting from age 55.
Do Women Stop Getting a Mammogram Once They Reach 75?
The prevalence of breast cancer continues with one in 12 women in their 70s and one in eight women in their 80s getting breast cancer. If women continue to be mobile, with no overwhelming health problems they should continue to get annual mammogram.
How Do I Decide in Special Situations?
Breast implant: Regular screening mammogram as per recommendation.
High-risk women: More frequent screening and early screening based on ACS or National Comprehensive Cancer Network guidelines. High-risk women include: personal history of invasive breast cancer or ductal carcinoma in situ (DCIS), atypical hyperplasia, BRCA 1/2 mutation, first degree relative with BRCA mutation, radiation treatment to the chest between ages 10-30.
How Do I Put the Evidence into Practice to Decide the Best Shared Decision with My Patient?
Despite revisions to guidelines, mammography practices have not changed due to the culture of general enthusiasm for testing in the United States, emphasis on benefits of screening, concern about missing the diagnosis and litigation, physician disagreement with guidelines, and rejection of the idea of screening mammogram harm11.
Whether to start the mammogram at age 40 or 50, or even earlier or later, must be individualized based on risk factors such as family history. As primary care physicians, we must engage patients in shared decision making. Although we cannot perfectly predict the individual risk for breast cancer, currently the best tools available to identify high-risk patients are the National Cancer Institute’s Breast Cancer Risk Assessment Tool or the Breast Cancer Surveillance Consortium’s Breast Cancer Risk Calculator. Shared decision making can be a time-consuming process for the primary care physician. Practically, it is easier to just order a routine mammogram at the age of 40. However, given the modest benefit of mammogram and real harms across all age groups, physicians are accountable to engage patients in making a shared decision about when and how often to undergo a screening mammogram. The Breast Cancer Screening Shared Decision Making Toolkit helps enable the clinician to engage patients effectively during the shared decision making12.
References available on the OAFP website.