The research, to be presented at the San Antonio Breast Cancer Symposium on Wednesday, Dec. 3, is the first prospective study to evaluate the hypothesis that DCIS (a common type of breast lesion that is harmless as long as it is confined to the milk ducts) can be treated by removing it along with a wide margin of healthy tissue on all sides. If surgery alone proved to be effective, women with DCIS could be spared the inconvenience of daily radiation treatments and their slight worsening of the breast's appearance, and the treatment costs would be lower.
At least one previous study had indicated that women who had wide excision of their DCIS and skipped radiation therapy had no higher risk of a recurrence DCIS than those who received it.
"This was a good hypothesis, but it certainly didn't work out in our study," said Jay Harris, M.D., chief of radiation oncology at Dana-Farber and the study's senior author. "The recurrence rate was surprise: We were all much more optimistic about not doing radiation."
The Dana-Farber research began in 1994 to test the hypothesis prospectively – enrolling patients at the time of treatment for DCIS and monitoring them for recurrences over subsequent years. To qualify, patients were required to have a DCIS lesion less than an inch across. The research was headed by Julia Wong, M.D., a radiation oncologist at Dana-Farber and Brigham and Women's in Boston, who is giving an oral presentation of the work at the San Antonio conference.
But as the study progressed toward its intended goal of treating 200 patients, the rate of recurrence (both repeated DCIS lesions and more-serious invasive cancers) rose to a level that had been previously agreed on as grounds to halt the study, and no new patients were enrolled as of July 2002.
The patients were accrued from Dana-Farber, Brigham and Women's Hospital, Beth Israel Deaconess Medical Center, and Massachusetts General Hospital. Among the 157 patients who had been followed for an average of about 3 ½ years, 13 had recurrences in the same breast that had previously been treated. Nine patients were diagnosed with a second DCIS lesion, and four had invasive breast cancer (it had spread outside the milk ducts into breast tissues). None of the patients had experienced spreading to the lymph nodes or beyond, and were treated with standard therapy.
"I think this study potentially will have a significant effect nationwide" on the treatment of DCIS, said Harris.
The American Cancer Society projected that more than 47,000 cases of DCIS will be diagnosed in 2003, the great majority on screening mammograms. Physicians believe that some proportion of DCIS lesions eventually spread beyond the milk ducts and become potentially dangerous invasive cancers. However, they cannot predict the fate of an individual DCIS lesion, and uncertainty exists about how aggressively to treat the disease.
Dana-Farber Cancer Institute is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute.