Mammograms have long been the standard screening tool for breast cancer. They work by using X-rays to create images of the breast tissue, helping to detect abnormalities, including tumors, at an early stage. While mammograms are beneficial in certain cases, there are also some significant downsides that deserve attention.
No screening tool is perfect. Every patient should understand the drawbacks, the benefits, and the concerns.
Benefits:
- Early detection: Mammograms are effective at identifying breast cancer early, often before a lump can be felt. This is important because early-stage breast cancer is more treatable and has a higher survival rate.
- Widely available: Mammograms are a standard screening method and are easily accessible in most healthcare systems. They are often covered by insurance and recommended annually or biennially for women over 40 or with a family history of breast cancer.
- Effective for detecting calcifications: Mammograms are particularly useful for spotting calcifications—small calcium deposits in the breast that may indicate the presence of early-stage breast cancer or precancerous conditions.
Drawbacks:
- Radiation exposure: Mammograms expose women to ionizing radiation, which can actually increase the risk of tissue damage and cancers. There is a concern about cumulative exposure over many years, especially because breast tissue is highly sensitive.
- False positives: Mammograms can lead to false positives, where an abnormality is detected but turns out to be benign. This can result in unnecessary stress, additional tests, and biopsies, which carry their own risks and emotional toll.
- Less effective for dense breasts: Women with dense breast tissue often experience less accurate mammograms because dense tissue and tumors both appear white on the X-ray, making it harder to detect cancer.
- Pain and discomfort: The compression of breast tissue required during a mammogram and necessary to get a clear image, but can be painful or uncomfortable for many women.
Concerns:
- Overdiagnosis: One of the more concerning aspects of mammograms is overdiagnosis—when a mammogram detects cancers that are slow-growing and may never cause harm during a woman’s lifetime. These “indolent” cancers may lead to unnecessary treatments, including surgery, chemotherapy, or radiation, which have significant side effects.
- Limited benefit for younger women: Mammograms are less effective in younger women (under 40) due to denser breast tissue. For this group, mammograms might not be as beneficial, and the risk of false positives is higher.
- Missed cancers (false negatives): In some cases, mammograms can miss cancers, particularly in women with dense breast tissue or those with fast-growing tumors. A false negative can create a false sense of security, delaying diagnosis and treatment.
Because mammograms have become the standard of care in breast cancer screening, most doctors are expected to recommend them as part of routine health checks for women. In fact, a doctor who advises against a mammogram could be seen as deviating from established medical guidelines, raising concerns about liability or non-compliance with standard practice.
One of the most significant issues with mammograms, however, is overdiagnosis. Since it’s not possible to know whether a cancer will be harmful or not, all are treated as dangerous. This leads to unnecessary interventions such as chemotherapy, radiation, or disfiguring surgeries, which can harm otherwise healthy women.
A common contributor to overdiagnosis is carcinoma in situ, which refers to abnormal cell changes that are not technically cancer. Studies have shown that many cases of carcinoma in situ never develop into invasive cancer, yet they are often treated as if they were, leading to overtreatment.
A study recently published in the Annals of Internal Medicine found that after 10 years of annual mammograms, studies show that 50-60% of women will likely experience at least one false positive result.
False positives often lead to additional diagnostic procedures, such as more imaging tests, follow-up mammograms, or biopsies. For example, it’s estimated that 28,000 unnecessary needle biopsies are performed each year as a result of screening, and there has been a sharp increase in mastectomies, particularly for carcinoma in situ, even though many of these cases would never have progressed to invasive cancer.
It’s also estimated that 20% of breast cancers are missed by mammograms. This number increases to 50% if you have dense breasts. Dense breasts refer to breasts that have a higher proportion of fibrous and glandular tissue compared to fatty tissue. This is a normal variation and can be found in many women, particularly those who are younger, though density can persist in older women as well. Breast density is usually determined through a mammogram, but it’s not something that can be felt during a physical exam.
On a mammogram, dense tissue appears white, which is problematic because tumors and other abnormalities also show up as white. This makes it difficult to distinguish between normal dense tissue and potentially cancerous masses. In contrast, fatty tissue appears dark, providing more contrast and making it easier to detect abnormalities. For women with dense breasts, other screening methods are recommended such as ultrasound or thermography.
Some experts suggest that mammograms have taken on a near “religious” status, with an unwavering belief in their benefits, despite substantial evidence showing the risks. Mammograms are often promoted as life-saving tools that protect women from breast cancer, but research suggests that these benefits are overstated, and the harm from overdiagnosis is significant.
We’ve reached a point where mammograms are almost seen as mandatory for every woman, every year, without question. However, avoiding conversations about the potential downsides of mammograms does women a disservice. Every woman is different, with her own unique physiology and risk factors, and she may need a personalized screening plan. Blind adherence to annual mammograms for every woman may not be the best approach, and encouraging more open, informed discussions around the true impact of these screenings can help ensure that we make the most appropriate choices for our health.