The troubling “overdiagnosis” of breast cancer

Breast cancer is a scary diagnosis. Unfortunately, though, one in eight American women will have that terrifying news delivered in their lifetimes.

Usually the diagnosis comes on the heels of a mammogram — the first-line screening test the CDC recommends every other year for women over age 50.

But there’s been a lot of debate about mammograms lately.
Here’s why: When a women hears those dreaded words — “You have breast cancer” — she’s often faced with a troubling choice. Sixty-eight percent of the time, the tumor is small. And while some of those small tumors develop into dangerous cancers, many never become a problem. The trouble is, that it’s impossible to tell at the outset which tumors will cause problems later and which won’t. So without complete information, women are forced to decide whether to have potentially unnecessary treatment or to wait and see, and maybe risk the cancer spreading.

This is an issue I confront at least once or twice per week in my practice. It is devastating to the woman and her family and leaves you wondering what to do. On one hand, you don’t want to live with cancer in your body. On the other, the treatments — mastectomy, chemotherapy, radiation — have lasting and serious effects. They’re not to be undertaken lightly.

A study published recently in the New England Journal of Medicine added fuel to the mammography controversy by looking at it from a statistical perspective. And they found that mammography screening results in an overdiagnosis of breast cancer “beyond what is generally recognized.”

Overdiagnosis refers to cancer diagnoses based on the tumors that wouldn’t end up becoming a problem. Ones that would never lead to clinical symptoms if left untreated.

To determine the prevalence of overdiagnosis, the authors looked at data from breast cancer diagnoses in the 1970s, before mammograms were common practice, and compared them to diagnoses from the early 2000s. And they found that the incidence of large tumors decreased during that time by 30 cases per 100,000 women, while small tumor incidence increased by 162 cases per 100,000 women.

That sounds pretty impressive, until you realize that rates of the most aggressive form of breast cancer — metastatic breast cancer — haven’t budged. Even as fewer large tumors are being found and more small ones are being caught early, the rates of aggressive cancer remain the same.

According to this study’s authors, that’s because of overdiagnosis. Only a small fraction of the small tumors that are being “caught early” would be expected to become large. Meanwhile, many more women are being faced with the decision to have radical procedures — such as double mastectomies, followed by chemotherapy, and radiation. Without knowing if any of it is necessary!

What these researchers are trying to point out is that while mammography screening has its benefits, it also has risks. And one of those risks is unnecessary, life-altering treatment.

Now of course, there are many within the scientific community who argue the other side of this coin. They believe that the increased diagnosis of small tumors, and the fact that aggressive cancer rates has remained steady — is proof that cancer is on the rise.

Clearly I am in the camp that believes what we’re seeing is an epidemic of overdiaganosis. I mean, what is better for Big Pharma than more disease — especially cancer. After all, with such a frightening diagnosis, people are much more willing to undergo very expensive therapies.

When it comes to breast cancer, I believe we should move toward better, more targeted screening of women who are at a higher risk, rather than broadly screening the general population. After all, most people are not at high risk of developing harmful breast cancer.

And in the meantime, perhaps we should be smarter about mammograms, and stop making them “standard operating procedure.” Instead, maybe it should be a choice that each woman makes for herself.