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.”