In cancer, as in other areas of medicine, early detection can save lives. But the screening tests used to find early tumors also detect disease that would never cause problems — disease you'll die with but not from. Managing those cases means giving potentially harmful treatment to patients who won't benefit.
DCIS, or ductal carcinoma in situ, is the poster child of this dilemma. Before routine mammograms, only about 1 percent of U.S. breast cancer cases were DCIS. Now nearly 65,000 women a year — about 22 percent of those with breast cancer — are diagnosed with DCIS.
DCIS, also known as Stage 0 breast cancer, is not life-threatening, and not all cases will progress to invasive cancer. But because there is no reliable way to determine which ones will, nearly all DCIS is surgically removed with a lumpectomy or mastectomy (and sometimes the healthy breast is removed prophylactically). Most DCIS patients also are offered radiation and drugs.