How does mammography improve these stats? Researchers generally agree that mammograms save lives, but—this is critical—catching breast cancer early changes the outcome in only 15 percent of cases. So consider the actual numbers: For the average 40-year-old woman, annual mammography for a decade increases one's overall chance of breast cancer survival from roughly 99.7 percent to 99.8 percent. That is, it increases the final batting average by only 0.001. According to the National Cancer Institute, there's also a downside. During this time, half of all screened women will have at least one suspicious mammogram, and one-quarter of them will end up getting a biopsy. Mammograms in women from 40 to 50 years old cause a huge number of false positives, resulting in about 100 biopsies for every life saved. Even more worrisome: It's possible the radiation from those mammograms may end up causing more cancers than they prevent.The false positives discussed here and in the Gladwell piece seem to be the real key--that mammograms before 50 do a very slight bit of good in detecting some cancer but the false positives may create a great deal of unnecessary havoc. The Slate piece recommends approaches that focus on a less blunt indicator than age but other risk factors instead. Would seem to be obvious, but after years of preaching one set of recommendations, it is hard to turn the ship around.
Wednesday, November 18, 2009
Reading is Fundamental
Seems to be a critical tipping point on mammograms lately. Gladwell has one essay on the difficulties of reading mammograms in his new book of old essays, that reading of them is as much art as science. Plenty of newspaper articles on the controversy plus one spiffy Slate post that takes the Belichick 4 and 2 decision and turns it into a decision about the probabilities of breast cancer and detection.