WASHINGTON (AP) — A new report estimates that the U.S. spends $4 billion a year on unnecessary medical costs due to mammograms that generate false alarms, and on treatment of certain breast tumors that are unlikely to cause problems. The Health Affairs study published Monday adds to a medical debate about the costs and benefits of some cancer screenings. Breast cancer is the second most common cause of cancer deaths among American women, claiming nearly 41,000 lives a year. Annual mammograms starting at age 40 have long been considered standard for preventive care, because cancer is easier to treat if detected early. But recently there's been disagreement about screening for younger women.Read more on NewsOK.com