Some Breast Cancers May Regress on Their Own

In fact, there have been 32 cases of spontaneous regression of breast cancer reported in one recent review of the medical literature. And not all actual cases of spontaneous regression end up being documented.

In addition, autopsy studies have revealed that many women die without ever knowing they had a breast cancer.

One expert was intrigued by the findings.

"The study is very provocative and it generates an interesting hypothesis: that it's possible some screen-detected breast cancers would not ever lead to death from breast cancer and are unnecessarily diagnosed and treated," said Dr. Jeanne Mandelblatt, associate director for population sciences at Georgetown University's Lombardi Comprehensive Cancer Center in Washington, D.C.

"But this study design can't prove or disprove that hypothesis," she added. "This study is inconclusive because these women were not randomized; there's no data about the tumor sizes or tumor characteristics in the two groups, and no data about the breast cancer death rate in the two groups."

Still, the finds should impact breast cancer research, experts say. "If the spontaneous remission hypothesis is credible, it should cause a major re-evaluation in the approach to breast cancer research and treatment," wrote Robert Kaplan, of the University of California, Los Angeles, and Dr. Franz Porzsolt of the Clinical Economics University of Ulm, Germany, in an editorial that accompanied the journal article. "Certainly, it is worthy of further evaluation."

Right now, however, doctors cannot tell a "bad" breast tumor from a potentially harmless one, so regular mammography screening is still valuable.

"For women, the take-home message remains that mammography done as recommended does decrease the chance of dying from breast cancer across the general population," Mandelblatt said. "Women need to know that there are risks and benefits to all medical interventions, including screening mammography, and the policy recommending mammography is based on the fact that the benefits outweigh some of these harms."

More information

There's more on mammography screening at the U.S. Agency for Healthcare Research and Quality.

SOURCES: Jay Brooks, M.D., chairman of hematology/oncology, Ochsner Health System, Baton Rouge, La.; Jeanne Mandelblatt, M.D., associate director for population sciences, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, D.C; Nov. 24, 2008, Archives of Internal Medicine