Mammogram stats

Every year in the US, hundreds of thousands of women are diagnosed with an early stage of breast cancer. But most early breast cancers are actually precancerous tumors that may or may not progress to true cancer. Thus, three out of four who are diagnosed with breast cancer suffer the complications of surgery, radiation therapy, hormone therapy, and chemotherapy with no benefit. Moreover, about one in four mammograms result in false positives, requiring multiple follow-up treatments and doctor visits, only to learn that they had no cancer after all.

No recent study has ever shown that mammograms have prolonged the lives of American women. Although mammograms save some lives, given the advances in breast cancer treatments, mammograms haven’t had an impact on overall mortality.

Here are the recent stats: For every 1,000 women screened every two years, most will have a false-positive mammogram during the next ten years, 146 will have an unnecessary biopsy, 7 will have a fatal case of breast cancer prevented, and 19 will be diagnosed with a cancer that never would have killed them. Among the 19 per 1000 who are over-diagnosed, 99 percent will have surgery, 70 percent radiation therapy, 70 percent hormone therapy, and 25 percent chemotherapy—all without benefit.

Scientists have no way of knowing who will benefit by screening. You might reasonably choose to have mammograms on the off chance that you might be one of the seven who has her life saved by screening, but also recognizing that you might be one of the nineteen who will undergo unnecessary treatment. Or, like me, you could skip the whole business. (I think I had one or two mammograms about 30 years ago.)

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