Is a mammogram worthwhile?
Some older women might be better off not knowing since they are likely to die of other causes
The shutdowns and fears provoked by the COVID-19 pandemic threw a monkey wrench into many aspects of routine medical care, especially for older people justifiably wary about being exposed to the virus in a medical setting. While many facilities have now created “safe spaces” to resume in-person exams, some of the resulting postponements of routine checkups can have a major impact on the severity of an undetected or untreated disease and sometimes even the chances of survival.
One of these is screening mammography, especially for women 75 and older, a group that has received conflicting advice for years about the need for, and ideal frequency of, routine breast exams.
On one hand, there’s no denying that breast cancer becomes increasingly common as women age and that finding this cancer in its early stages typically results in simpler and more effective treatment. Indeed, the earliest stage of invasive breast cancer has a fiveyear survival rate of 99%.
On the other hand, some older women might be better off not ever knowing they have breast cancer because they are likely to die of some other cause long before an undiagnosed and untreated breast cancer threatens their health and lives. Yet once a woman is told she has breast cancer after a routine mammogram, she faces a decision about treatment that can have a negative impact on her emotional and physical well-being.
Further complicating matters is the current inability of cancer specialists to say with certainty which breast cancers found on a mammogram may not warrant any treatment because they are too slowgrowing to be life-threatening or may even have the potential to disappear on their own. A Norwegian study published in 2008 found fewer invasive breast cancers among women screened only once in six years than among a comparable group screened biannually for six years, suggesting that some mammogram-detected cancers in the latter group would have regressed spontaneously.
Although the incidence and mortality associated with breast cancer increase with age, there is some evidence to suggest that in general, the disease in older women tends to be less aggressive and more likely to have a favorable prognosis. It is now possible to get a genetic test called Oncotype DX that predicts the risk of a breast cancer recurrence and the disease’s likely response to chemotherapy.
Given the many conflicting guidelines and confusing statistics, making a rational decision about screening can be quite challenging, especially for women who know others found to have curable cancers in their later years.
The American Cancer Society guidelines for women with an average risk of developing breast cancer advises yearly mammograms starting at age 45 (or 40 if a woman prefers), changing to every other year (or every year if preferred) at age 55 and continuing every year or two for as long as they remain healthy enough to have a life expectancy of 10 or more years.
The U.S. Preventive Services Task Force, however, recommends stopping routine mammograms at age 75 regardless of a woman’s remaining life expectancy. Yet there are other professional guidelines recommending continued exams for women in generally good health who have a life expectancy of at least five years.
Then there is data from an analysis of 763,256 mammography screenings done between 2007 and 2017 that found cancer in 3,944 women, 10% of whom were 75 and older. The study’s author, Dr. Stamatia Destounis, radiologist at Elizabeth Wende Breast Care in Rochester, New York, reported that most of the cancers in the older women were invasive and of a grade that should get treated. Nearly two-thirds had the potential to spread and grow quickly.
Destounis told Healthline, “There are benefits of screening yearly after age 75. Mammography continues to detect invasive cancers in this population that are node negative and low stage, allowing these women to undergo less invasive treatment. The age to stop screening should be based on each woman’s health status and not defined by her age.”
Still, there is one fact that all older women should know: According to Diana Miglioretti, a biostatistician at the University of California in Davis, “There is no evidence from randomized controlled trials on whether screening women ages 75 or older reduces breast cancer mortality. Evidence suggests the benefits of screening are not seen until 10 years later.” She said there is also a risk of overdiagnosis that increases with age — finding a cancer that would not have harmed the woman in her lifetime.
In an interview, Dr. Mara A. Schonberg, internist at Beth Israel Deaconess Medical Center in Boston, echoed Miglioretti’s concerns. “Overdetection in older women is a problem, and even finding breast cancer is not always good. It takes at least 10 years of screening 1,000 women aged 50 to 74 to avoid one breast cancer death, and probably even longer in women over 75 in whom breast cancer tends to be more indolent. It’s not clear that all the aggressive treatment older women get is needed.”
Furthermore, among 1,000 women age 75 to 84 who continue to have mammograms for five years, 100 will get false alarms, creating anxiety and prompting a slew of tests that do not find cancer. With continued mammography, within five years three such older women in 1,000 will die of breast cancer, as against four women who do not have mammograms, Schonberg reported. She also noted that among women age 75 to 84 who die in the next five years, 12 times more will succumb to heart disease than to breast cancer.
To help women decide about whether continuing to get regular mammograms after age 75 is in their best interests, Schonberg and her colleagues devised a decision aid.
It asks 10 questions about age and health status, including body weight, physical ability, smoking history and preexisting health conditions like diabetes. The lower a woman’s health risks, the lower her score, and the more likely that a mammogram may help her live longer.
Schonberg said she hopes that before handing their older patients prescriptions for a mammogram, doctors would first have them complete the decision aid.