On Oct. 20, 2015, the American Cancer Society (ACS) released updated breast cancer screening guidelines for women at AVERAGE risk of breast cancer. The guidelines recommend:
- All women should become familiar with the potential benefits, limitations, and harms associated with breast cancer screening.
- Women with an average risk of breast cancer should undergo regular screening mammography starting at age 45.
- Women who are 45 to 54 years should be screened annually.
- Women who are 55 and older should transition to biennial screening [screening every 2 years] or have the opportunity to continue screening annually.
- Women should have the opportunity to begin annual screening between the ages of 40 and 44.
- Women should continue screening as long as their overall health is good and they have a life expectancy of 10 years or more.
- The ACS does not recommend clinical breast examination for breast cancer screening among average-risk women at any age.
These new ACS guidelines reignited the simmering debate about the value of screening mammograms. Several large studies, including a review by the U.S. Preventive Services Task Force in 2009 and a study on the causes of death in the United Kingdom in 2013, questioned the value of screening mammograms.
Doctors who question the value of mammograms say that while mammograms do save lives, for each breast cancer death prevented, three to four women are overdiagnosed. Overdiagnosis means either:
- a screening mammogram finds a suspicious area that would have been eventually diagnosed as cancer by other means, without any effect on prognosis
- a screening mammogram finds a suspicious area that never would have affected a woman’s health if it hadn’t been found or treated
False positive results from screening mammograms also have helped fuel the debate about the value of breast cancer screening. When a mammogram shows an abnormal area that looks like a cancer but turns out to be normal, it’s called a false positive. Ultimately the news is good: no breast cancer. But the suspicious area usually requires follow-up with more than one doctor, extra tests, and extra procedures, including a possible biopsy. There are psychological, physical, and economic costs that come with a false positive.
One of the studies the ACS used to develop its new breast cancer screening guidelines found that menopausal status was a better indicator of how often women should have screening mammograms than age. Which makes us ask, “Then why didn’t the ACS say that rather than assigning somewhat arbitrary ages to its guidelines?”
The research was published online on Oct. 20, 2015 by the journal JAMA Oncology. Read “Breast Tumor Prognostic Characteristics and Biennial vs Annual Mammography, Age, and Menopausal Status.”
In the study, the researchers looked at the characteristics of breast cancers diagnosed in the context of the women’s ages, how often they were screened, their menopausal status, and whether or not they used postmenopausal hormone replacement therapy (HRT).
The study included 15,440 women ages 40 to 85 who were diagnosed with either invasive breast cancer or DCIS from 1996 to 2012:
- more than 85% of the women were 50 or older
- more than 78% were white
- more than 63% were postmenopausal
- 13.1% (2,027 women) were premenopausal
All the women had at least two screening mammograms at intervals of either 11-14 months (every year) or 23-26 months (every 2 years) before they were diagnosed.
Compared to premenopausal women who were screened every year, premenopausal women who were screened every 2 years were more likely to be diagnosed with cancers that were:
- stage IIB or higher
- 15 mm or larger
Doctors consider these characteristics to be less favorable, which means the cancer is considered more aggressive. So premenopausal women who were screened every 2 years were diagnosed with breast cancers that were more aggressive compared to women who were screened every year.
The number of more aggressive cancers diagnosed in postmenopausal women was about the same whether they were screened every year or every 2 years. This was also true whether or not the women took HRT.
"Our results suggest that menopausal status may be more important than age when determining screening intervals," said Diana Miglioretti, Dean’s Professor in Biostatistics at the University of California, Davis and lead author of the study. "They suggest that postmenopausal women may be safely screened every two years. In contrast, premenopausal women who are undergoing screening may want to be screened annually to increase their chances of diagnosing cancer at an early stage."
It’s important to know that this study did not look at mortality. So we don’t know if finding more cancers with characteristics that were less favorable in premenopausal women who were screened every 2 years led to more deaths from breast cancer.
It’s also important to know that not all women go through menopause the same way or at the same age. Some women who have had their ovaries removed or are using certain types of birth control that eliminate periods may not know their menopausal status.
And finally, it’s important to know that right now, there is no way to tell which breast cancers will grow so slowly that they will never impact a woman’s health and which cancers will grow and spread quickly. It is this uncertainty that makes most doctors recommend treating any breast cancer that is found, including DCIS.
At Breastcancer.org, we believe that a woman’s best chance for early detection requires coordination of our current screening tools:
- high-quality mammography
- clinical breast exam
- self-breast exam
The reality is that every woman is at risk for breast cancer, and this risk tends to increase over time. It’s important to regularly talk to your doctor about your personal level of breast cancer risk and update any health information related to your risk throughout your life. Here are some points you may want to discuss with your doctor:
- family history of breast or other related cancers (ovarian, melanoma)
- any test results for abnormal genes linked to a high risk of breast cancer
- results of past breast biopsies, even if they were benign
- personal history of being treated with radiation to the face and/or chest before age 30
- breast density
- weight, if you’re overweight or obese
- level of physical activity
- any use of postmenopausal combined hormone replacement therapy (HRT)
- the length of time you used hormonal contraceptives (birth control pills, for example), if any
- alcohol consumption, if you regularly drink more than three alcoholic beverages per week
- the amount of processed food and trans fats you eat
- your smoking history
- whether or not you had a full-term pregnancy or breastfed
Breastcancer.org stands by its recommendation that ALL women have mammograms annually starting at age 40. We also believe that monthly breast self-exam and annual physical exams by a doctor are essential parts of an overall breast cancer screening strategy. If you’re at high risk for breast cancer, you should talk to your doctor about starting annual mammograms at a younger age and consider other screening tools (such as MRI or ultrasound) to maximize the opportunity for early detection.