Are you confused about whether to have a mammogram? Join the crowd. Everywhere you turn, there’s conflicting information about the mammography controversy.
The American Cancer Society says one thing, and the U.S. Preventive Services Task Force (USPSTF) says another. Bureaucrats and politicians—who have no medical background whatsoever but are eager to appease—join the fray with impassioned pronouncements about these screenings.
What get lost in all this noise are the hard facts. Let’s look at some of the latest scientific research on routine mammography screening.
Overdiagnosis and Overtreatment
Screening mammography has not reduced the incidence of advanced breast cancer or lowered death rates. However, false positive mammograms are common. Screening has spawned an epidemic of false positives (suspicious findings that turn out to be normal), as well as overdiagnosis (diagnosis of disease that will never cause illness or death), and overtreatment (unnecessary medical interventions).
The rationale for screening is that detection and treatment of breast cancer in its earliest stages will prevent the development of advanced disease and deaths. Problem is, it’s a faulty rationale.
Breast cancer screening has never been shown to reduce overall mortality rates. Since mammography programs were launched in the 1970s, deaths from breast cancer have declined, but that decline has been offset by deaths from other causes in women who were screened, including adverse effects of overtreatment (e.g., increased risk of heart and lung problems from radiation therapy). Furthermore, the frequency of advanced cancers—the deadly kind that mammograms are supposed to prevent—has held steady. The most likely reason for the reduction in breast cancer deaths is the development of better treatments, not early detection.
Evidence has been building for years. A 2017 study comparing long-term outcomes of Danish women who had mammograms with those who did not concluded that screening did not reduce the incidence of advanced tumors.
Another recent study, which tracked 8 million Dutch women over 24 years, found that the Netherlands’ biennial (every two years) screening program has had little effect on advanced cancer or cancer deaths.
Serious Collateral Damage
It is increasingly clear that breast cancer screening has not lived up to its early promise and ongoing hype. Even worse, it inflicts tremendous collateral damage. Mammography may not prevent advanced cancer, but it is very good at picking up “suspicious” benign changes and early-stage disease.
More than half of women who have yearly mammograms in their 40s have at least one false positive by age 50. Of course it’s a relief when it turns out to be benign, but it’s still stressful, and additional tests (X-rays, biopsies, surgeries, etc.) have risks of their own.
Overdiagnosis is even more harmful. Not only does it burden women with the erroneous belief that they have a potentially fatal disease, but it also leads to unnecessary treatment. The studies discussed earlier found that a third to half of the breast cancers detected on screening represented overdiagnosis!
For example, 20–25 percent of cancers seen on mammograms are ductal carcinoma in situ (DCIS): noninvasive disease confined to the milk ducts. DCIS—called stage 0 breast cancer by some experts but not even considered to be cancer by others—is not life threatening. Although it can progress to invasive disease, in most cases it does not. Nevertheless, the usual course is lumpectomy and radiation or a complete mastectomy, often followed by years of hormone therapy, with all their attendant risks.
Cancer is a terrifying diagnosis, and many patients just want it gone, no matter how slight the risk. However, the fact remains that treating early-stage cancers that would have gone undetected if not for screening mammograms—and would never adversely affect health if left alone—can only cause harm.
Despite these serious flaws, screening mammography has achieved a cult-like following. Virtually all primary care and OB/GYN physicians recommend it. More conservative doctors may go with guidelines from the USPSTF, an independent advisory expert panel that recommends mammograms every other year for women ages 50–74. More will follow the American Cancer Society’s schedule of annual mammograms from ages 45 to 54, then every other year after that.
But most side with the American College of Radiology, an organization of radiologists and radiation oncologists that calls for yearly mammograms for all women over age 40. Screening advocates such as nonprofits and physician groups—many with financial support from imaging centers, device manufacturers, drug companies, and other vested interests—and their cheerleaders in the media have turned breast cancer awareness into an emotionally charged circus.
Even the US legislature is in on the gig. After the USPSTF came out with their recommendation to delay screening until age 50, Congress passed laws overriding it and requiring insurers to cover mammograms starting at age 40. These efforts have paid off. More than 65 percent of US women in their 40s and older have had a mammogram in the past two years, and screening is a $10 billion a year business.
Facts, Not Fear
Do not mistake this as a personal bias against cancer screenings. Many screenings that have proven effective in reducing deaths, such as cervical and colorectal cancer. That is not the case with breast cancer screening.
One day, a valid screening tool will eventually be developed—one that can analyze tumor aggressiveness and determine who would benefit from treatment and who would be harmed by overtreatment. Until then, regular mammograms for high-risk individuals are appropriate, but asymptomatic women with no family history should rethink the wisdom of screening.
Whether or not you have a mammogram is a personal choice, but I urge you to learn more about this and discuss it with your doctor. Your decision should be based on facts, not fear.