As many as 60,000 American women each year are told they have a very early stage of breast cancer — Stage 0, as it is commonly known — a possible precursor to what could be a deadly tumor. And almost every one of the women has either a lumpectomy or a mastectomy, and often a double mastectomy, removing a healthy breast as well.
Yet it now appears that treatment may make no difference in their outcomes. Patients with this condition had close to the same likelihood of dying of breast cancer as women in the general population, and the few who died did so despite treatment, not for lack of it, researchers reported Thursday in JAMA Oncology.
Their conclusions were based on the most extensive collection of data ever analyzed on the condition, known as ductal carcinoma in situ, or D.C.I.S.: 100,000 women followed for 20 years. The findings are likely to fan debate about whether tens of thousands of patients are undergoing unnecessary and sometimes disfiguring treatments for premalignant conditions that are unlikely to develop into life-threatening cancers.
Diagnoses of D.C.I.S., involving abnormal cells confined to the milk ducts of the breast, have soared in recent decades. They now account for as much as a quarter of cancer diagnoses made with mammography, as radiologists find smaller and smaller lesions. But the new data on outcomes raises provocative questions: Is D.C.I.S. cancer, a precursor to the disease or just a risk factor for some women? Is there any reason for most patients with the diagnosis to receive brutal therapies? If treatment does not make a difference, should women even be told they have the condition?
Such questions are unlikely to be resolved by the new study. Some doctors, including the chief breast cancer surgeon at Memorial Sloan Kettering Cancer Center, said they did not see reason to change the current approach.
Dr. Otis W. Brawley, chief medical officer at the American Cancer Society, said he was not ready to abandon treatment until a large clinical trial is done that randomly assigns women to receive mastectomies, lumpectomies or no treatment for D.C.I.S., and that shows treatment is unnecessary for most patients. But Dr. Brawley, who was not involved in the study, also said he had no doubt that treatment had been excessive.
“In medicine, we have a tendency to get too enthusiastic about a technique and overuse it,” Dr. Brawley said. “This has happened with the treatment of D.C.I.S.”