Every health magazine on the supermarket checkout aisle touts it. Women's health activists have long championed its practice. And most cancer doctors strongly maintain that it belongs as a standard of care.

So why is it that studies keep coming to the conclusion that breast self-exams are highly unlikely to reduce breast cancer deaths and, in fact, might do more harm than good to healthy women?

This disconnect between recommendation and research cropped up again in early August, when a review by the Cochrane Collaborative — an international group that evaluates medical science — agreed with two earlier studies showing no evidence that screening reduces deaths.

In saying that breast self-exams "cannot be recommended," the organization's statement warns that research "suggests harm in terms of increased numbers of benign lesions identified and an increased number of biopsies performed."

Two earlier studies involving Russian and Chinese women came to similar conclusions.

Dr. David B. Thomas, who headed Seattle's Fred Hutchinson Cancer Research Center's 2002 study of 250,000 Chinese women, told MSNBC.com: "Our study shows that (a self-exam) is probably a waste of time. You're not going to get women sufficiently motivated to practice it well enough and frequently enough to make that big of a difference."

Also now weighing in against self-exams: the American Cancer Society; the U.S. Preventative Service Task Force, an expert panel that issues the federal government's official advice on preventive medicine; the National Breast Cancer Coalition; and the Journal for the National Cancer Institute.

And yet, there are just as many health-care providers who maintain that not having women do monthly breast self-exams is even more risky.

One vocal advocate is Dr. Balazs ("Ernie") Bodai, the director of Kaiser Permanente's breast surgical services in Sacramento, Calif., who gained renown for creating the breast-cancer awareness stamp.

"Talk to any busy breast cancer surgeon, and they'll tell you 30 percent of the diagnoses are made by the patient — not that they have cancer but they found their own lumps," Bodai says. "Just this morning, I saw a 37-year-old woman with a normal mammogram, but she found a lump and was proactive about it. And it turned out to be cancer."

Even more vocal is Dr. Marisa Weiss, a breast oncologist and founder of Breastcancer.org, who says the Cochrane guidelines are ill-advised.

"The world of early detection of breast cancer is imperfect," Weiss says in a statement. "(But) this report robs women of one of the key tools in what is already a limited arsenal for detection. ... It sends the wrong message to women about their role in their own health care."

Susan Stone, chief of certified nurse midwives for Kaiser Permanente in Sacramento, deals with women daily. She stresses self-exams.

"The midwifery model of care is based on empowering women to be the experts on their own bodies and health," she says. "I encourage women to check their own breasts once in a while so they can know what's normal for them."