False Positives and Overdiagnoses

When you read about “false positive” rates in mammograms, what comes to mind? Or about breast cancer “overdiagnoses”? There have been a few articles on those topics lately, so below is a brief explanation of what false positives and overdiagnoses are and what the latest findings mean to mammography screening. 

In “research speak,” a false positive on a mammogram is when a mammogram picks up an abnormal finding. This finding is anything that would require further investigation, from a cyst to calcifications to a solid mass. It also includes mammograms where a radiologist thinks that something might be present in the image, but there is nothing concerning after further scans. A false-positive finding in a mammogram does NOT mean that someone is told that they have cancer when they actually do not. Mammograms cannot diagnose breast cancer; only a microscopic examination of tumor tissue after a biopsy can do that. 

While “false positive” is technically correct when it comes to explaining the results of a mammogram, this term can be scary for people outside of the medical field to hear and something that journalists can intentionally or unintentionally exploit as “clickbait.” However, false positives are still something the medical community should work to reduce. False positives lead to increased costs for further testing and anxiety in patients. Still, VBCF believes the answer is not fewer mammograms but rather improved screening technology to improve test accuracy. 

If you get a callback for a mammogram so they can get a better picture of something, keep in mind that only 10% of callbacks lead to cancer diagnoses. It is very important to follow through on a callback, but try not to worry about the situation. Mammograms are a great tool, but they aren’t perfect. Callbacks indicate that the radiologist needs more pictures to give a clear interpretation of anything they see. One good piece of news is that a study recently confirmed what many professionals have believed for a while, 3D mammograms result in fewer false positives and unnecessary callbacks than standard digital mammograms.

Breast cancer overdiagnosis is another popular issue, similar to false positives, that can lead people to question the value of breast cancer screening. When breast cancer is determined to be “overdiagnosed,” that means that though the tissue is cancerous, it likely would have never threatened the patient’s life, so treatment is determined to be unnecessary after the fact. An individual Stage 0 tumor, or ductal carcinoma in situ (DCIS), might never have the capacity to spread beyond the breast duct. 

Here’s the problem: it isn’t yet known how to tell which small, non-invasive tumors will spread or when and which could continue existing harmlessly within the body. Because of this, the medical community (and patients) often err on the side of caution and treat the cancer, meaning that the patient will undergo surgery and perhaps radiation and hormone treatment that may or may not have been lifesaving. 

One group that is a more frequent source of breast cancer overdiagnoses are women over the age of 75. It can be easy to fall into a trap that suggests that women should no longer receive regular mammograms over a certain age, but age alone does not describe one’s health or quality of life. Though cancer is more common as people age, it also tends to grow more slowly, meaning that breast cancer could pose no threat to the person’s life for years. And as people age, they are also more likely to have chronic or other conditions, meaning that treatment for breast cancer in some people would cause undue harm to health and finances for little to no survival benefit. 

As the medical community continues to learn more about what causes breast cancer to spread, it’s important for those over 75 to have conversations with their medical team about continuing to get mammograms, taking into account their current health and quality of life. A recent study has shown that there is less breast cancer overdiagnosis than previously thought, which is a good sign. Again, VBCF believes that increased research into which DCIS tumors will grow to become invasive and not restricting access to mammograms is the right way to address this issue.

As always, talk to your medical provider about the recommended breast cancer screening and frequency that is right for you.