Warning: I am not writing about Angelina Jolie. I am not asking whether women like Jolie, with a strong family histories of breast cancer and known genetic mutations, should consider having bilateral mastectomies. Women like Jolie face extremely high lifetime risks of breast cancer, and thus must make difficult decisions about whether to receive prophylactic mastectomies – surgical removal of healthy breasts in an effort to prevent them from harboring future cancers. I’m not writing about people like that.
Instead, I am writing about women who actually have been diagnosed with breast cancer, but who do not have any known genetic mutation predisposing them to such tumors. I’m wondering in these cases: Is it rational for women to ask their doctors to not only remove the affected breast, but also to perform a contralateral prophylactic mastectomy (hereon: CPM) – a procedure to remove the unaffected breast?
I will tell you my answer right now, so I can walk you through my reasoning without misleading you as to my intentions. I think the decision whether to receive CPM is a very difficult one. Unfortunately, many women make this decision even though they are poorly informed about the pros and cons of the procedure. Given what they believe about CPM, it is totally rational to receive that procedure. But if they were better informed? Then, honestly, I’m not sure so many women would receive that procedure.
But I might be wrong. I expect that CPM decisions, like many decisions most of us make in our lives, are often influenced by highly intuitive thought processes, ones often not influenced by informational campaigns. In short, I refuse to call this decision rational or irrational. Instead, I see it as a really hard call. But it’s a hard call we need to understand, because of what it tells us about the challenges of making good medical decisions.
Let’s start with the information that, plausibly, ought to guide such decisions. When women without genetic mutations (hereon: non-carriers) experience cancer in one breast, their risk of experiencing a cancer in the other breast is usually not dramatically different from the general population risk. To put a number on that: studies put the 10 year risk of contralateral cancer at about 5%. And with new breast cancer treatments, that risk has declined even further. So we are talking about an annual risk of less than a half a percent per year.
A second fact of note: there is no evidence, none, that CPM reduces a woman’s chance of dying of breast cancer. With such a low risk of a contralateral cancer arising, and such aggressive monitoring of such cancer in women with breast cancer histories, most such cancers are found at very early and very treatable stages.
This last fact is important to keep in mind when we look at why women choose CPM. According to a recent study in The Annals of Internal Medicine, more than 90% of women who receive CPM say they did so to increase their chance of long-term survival. Indeed, the majority of non-carriers who receive CPM significantly overestimate the impact the procedure will have on their risk of breast cancer recurrence, and on their chance of long-term survival.
In other words, many CPM decisions are either uninformed, or are being influenced by misperceptions. This finding is concerning given the dramatic rise in CPM rates in recent years. Back in the 90s, less than 5% of non-carriers received CPM after breast cancer diagnoses. Today, that figure is approaching 25% in many cancer centers.
I am in no way prepared to say that women who receive CPM are making poor choices. (To read the rest of this article, please visit Forbes.)