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Mammograms Annually or Not?

The latest news on mammography has a long history worth summarizing.

In 1980 a huge study was undertaken in Canada, investigating whether women who had annual careful breast exams derived any added benefit from also getting a routine, annual screening mammogram. (If anyone finds a lump, the woman herself or the breast examiner, a diagnostic mammogram is ordered to identify that lump.) The study was inspired by a previously noted discrepancy by age, whereby older women, but not younger women, benefitted from mammography. The women were treated differently for the first 5 years, and have been followed up now for 25 years. The total number was almost 90,000 women who underwent either exam or exam plus mammography.

It is important to clarify that the breast exam in the study was a careful exam. A thorough breast exam should take several minutes, depending on the size of your breast, up to 5 minutes per breast, and include both gentle and deeper palpation!

The women studied were between 40-49 and 50-59. Older women were not included in this study, but there was no age discrepancy between the two groups in this study. Confirming the accuracy of the “randomization” of the two groups, it turned out that the two groups were almost exactly equal in the number of breast cancer deaths, a good marker of serious breast cancer cases.

However, differences between the two groups did emerge. The exam plus mammo group had an excess of breast cancers diagnosed, to the tune of 106 women who were diagnosed and treated for cancer, but for a cancer that was never going to be life-threatening. Working with the numbers, it turns out that one woman is “over-diagnosed” for every 424 women receiving annual mammography during the five year study period.

Two important takeaways from this: make sure you get a careful exam of your breasts in your annual visit to your doctor, and  make your own personal decision about whether or not to get an annual mammogram. 

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