· The direction-finding technology employed by the global positioning system in your car is now being used in the treatment of prostate cancer, according to ABC News's Cutting Edge Reports. The network describes the benefits of the newly targeted radiation treatment called the Calypso 4D Localization System on its Web site, http://abcnews.go.com/Health. Doctors implant tiny electromagnetic sensors into the prostate that updates a tumor's position and sends the coordinates to a computer. This ensures the radiation beam targets only the tumor and not the surrounding tissue and organs. Scientists are hoping that this technology, which was recently approved by the FDA, will soon be applied to other moving tumors, such as lung cancer, in which the tumor can shift position as the patient breathes.

· Sharon Moalem, who holds a PhD in neurogenetics, and Jonathan Prince, former speechwriter for President Bill Clinton, explain in Survival of the Sickest: A Medical Maverick Discovers Why We Need Disease (William Morrow, $25.95) why diseases persist in modern society despite rapid technological advances.

Informed by the kinds of medical oddities and eclectic facts that helped make bestsellers of "The Tipping Point" and "Freakonomics," the book suggests that evolution through natural selection favors a long life with disease over a short one without it. Along the way, the authors address such conundrums as: Do tanning salons lower cholesterol? Was diabetes evolution's response to the last Ice Age? Tidbits to leaven any conversation.

-- Rachel Zavala