Radiation therapist Jean Etienne holds a range compensator, which shapes the depth to which the proton beam enters a patient's body to target a tumor. Rebecca Davis/NPR hide caption

itoggle caption Rebecca Davis/NPR

Terry Dyroff, at home in Silver Spring, Md., got a PSA blood test that led to a prostate biopsy. The biopsy found no cancer, but it gave him a life-threatening infection. Jose Luis Magana/AP hide caption

itoggle caption Jose Luis Magana/AP

The problem of breast cancer overdiagnosis with mammograms is similar to the dilemma faced by men diagnosed with prostate cancer because of a PSA test. Damian Dovarganes/AP hide caption

itoggle caption Damian Dovarganes/AP

Former House Speaker Newt Gingrich makes a point during the presidential debate sponsored at Dartmouth College in Hanover, New Hampshire, Tuesday night.

Toni Sandys/The Washington Post via AP hide caption

itoggle caption Toni Sandys/The Washington Post via AP