How much do we really need mammograms?

With the recent controversy surrounding prostate cancer screening, it’s now time to look at mammograms and breast cancer screening.

Like the PSA test, there is little data saying that mammograms decrease the mortality rate from breast cancer. And indeed, some of the harms of breast cancer screening are being publicized in the UK.

The number needed to treat, a statistic that is gaining increasing relevance in mainstream health reporting, is mentioned prominently in this NY Times article: “A 2006 analysis by the Nordic Cochrane Center collaborative, an independent research and information center based in Copenhagen, found that for every 2,000 women age 50 to 70 who are screened for 10 years, one woman will be saved from dying of breast cancer, while 10 will have their lives disrupted unnecessarily by overtreatment.”

And the price of overdiagnosis and overtreatment can be significant, ranging from a breast biopsy to a mastectomy.

Merrill Goozner comments on the article, and like other forms of cancer screening, the vocal minority whose lives were saved from screening likely will have the emotional pull over the data suggesting mammogram’s lack of efficacy.

“What’s best for population health (and usually more economical) is no consolation for individuals who test positive and must make individual choices,” writes Mr. Goozner. “That’s why telling patients at that moment what their real odds are — the number needed to treat before one life will be saved — is crucial to informed medical decision-making.”

Indeed.

Comments

Nancy
Every time I get scanned for something an “incidental finding” shows up requiring more scans, tests and upset and amounting to nothing. I’m at the point now where I avoid preventative tests because they are more headache than they are worth.
Healthcare Observer
Many breast specialists do acknowledge that the raw benefit of screening alone is less than hoped for. But many also see screening as a fundamental enabler in the establishment of high performance breast cancer clinics – so there is much more to it.
Jen
While I understand the point – I would still argue it is worthwhile to have 10 lives disrupted by overtreatment than even one life lost from a lack of early detection.
I do agree, though, that we need to make time for these types of conversations as well as the emotional stories of the lives saved. Because if our technology today isn’t good enough – the public needs to know so we can do something about it.
IMO – in this case, a flawed system is better than nothing. But we can’t hide behind it forever.
Diora
Jen, this “disruption” can have consequences that go beyond inconvenience. Surgery, for example, has risks and while these risks may be small, when you consider a large numbers of women affected, they will add up. Overtreatment may damage someone’s health or quality of life forever. Is one woman’s life saved worth an unnecessary mastectomy (and associated risks of surgery)? What about 5 unnecessary mastectomies? What about unnecessary radiation treatment that increases one’s risk for heart disease and even sarcoma later in life? Yes, risks may be small, but so is the probability of an individual benefiting. Even anxiety from false positives that can be accompanied by a raise in blood pressure may be harmful to someone’s health. Again, you may say that this is a small price to pay for a decreased risk of dying from breast cancer, but when you consider that your risk of having at least one false positive within 10 years of screening is almost 50%, the number of women affected might be quite large.
Also, keep in mind that no study showed the decrease of all cause mortality from screening, only breast cancer mortality. So if, for example, more screened women die from heart disease, it is impossible to determine.
Another problem with emotional “my life was saved” stories is that in any particular case there is no real certainty that a particular life was indeed saved. In some cases the early cancer represented over-diagnosis so a woman may have lived a long life without ever knowing she had cancer. In other cases, the cancer could have still been curable if detected later. Yet in another case, the cancer can still come back and kill you anyway. It’s only in a subset of these “my life was saved” stories where one’s life was really saved.
I imagine that many women would indeed prefer mammograms, and it is fine. But I think that some women may refuse, and I believe their choice has to be respected. Currently there is this pervasive mentality that women have to be persuaded, dragged, shamed into having mammograms because it is “a responsible thing to do”. I think this has to stop. We are thinking and intelligent human beings who are capable of making our decision, but to do so we need accurate information.

How much do we really need mammograms?

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