Improved screening has resulted in the overdiagnosis and overtreatment of cancers that are not life-threatening, without significantly reducing the death rate from the disease, and the time has come to alter how cancer is detected, treated and defined, a panel of medical experts said Monday.

“Screening and patient awareness have increased the chance of identifying a spectrum of cancers, some of which are not life threatening,” a working group of the National Cancer Institute wrote in a commentary in the online version of the Journal of the American Medical Association. “Policies that prevent or reduce the chances of overdiagnosis and avoid overtreatment are needed, while maintaining those gains by which early detection is a major contributor to decreasing mortality.”

The opinion was published on the same day as an influential recommendation from the U.S. Preventive Services Task Force that called for annual CT scanning for lung cancer for high-risk patients — older heavy smokers and former smokers.

Laura J. Esserman, co-chair of the committee and director of the Breast Care Center at the University of California at San Francisco, said the messages of the two papers dovetail: Additional screening should be reserved for high-risk groups, and not every finding must result in action.

“More is not always better,” she said. “It’s pretty clear that cancer — the word now refers to a wide range of conditions, some of which will not progress and will not kill you. . . . We have to be a little bit more savvy.”

Breast and prostate cancers are prime examples, said Otis Brawley, chief medical officer of the American Cancer Society. “Looking at the epidemiology, a third of women have localized breast cancers that look like cancer but are never going to kill them,” he said. Yet a diagnosis that contains the word ‘cancer’ often causes so much anxiety for the patient and pressure on a physician to act that many women unnecessarily undergo radiation treatment or mastectomies, he said.

“We cure these women who have these localized tumors, but they didn’t need to be cured,” Brawley said.“That’s a hard concept for even doctors to understand now.”

On the other hand, the committee noted, early detection and removal of precancerous colon and cervical lesions has reduced the incidence of those cancers.

The committee recommended changing the names of some conditions and reserving the term “cancer” for lesions “with a reasonable likelihood of lethal progression if left untreated.”

For example, it suggested that “ductal carcinoma in situ,” the presence of abnormal cells in the milk duct of the breast, is not invasive and should not be labeled a cancer.

“Right now, we have women getting bilateral mastectomies for ductal carcinoma in situ, which is not a cancer,” Brawley said. “It’s the world turned upside down.”