Based on this evidence, patients with DCIS who are HER2/neu-positive might benefit from a biologic agent such as trastuzumab, which specifically targets the HER2/neu receptor, while those without this marker may be fine with a less aggressive therapeutic approach than is currently recommended for DCIS, the researchers concluded.

"Most patients with DCIS … will not die of their disease; it's a highly curable disease," said Sharon Nofech-Mozes, MD, clinical fellow, Sunnybrook and Women's College Hospital, Toronto, Ontario, Canada. "Yet, with no further treatment rather than surgical resection, 25% [of these cancers] will recur, and about half of them will recur as invasive cancer."

All patients with DCIS are now subjected to 6 weeks of radiotherapy after they undergo breast resection. "If you go back and do the math, you realize that most of these patients would never have recurred, so they are subjected to 6 weeks of radiation unnecessarily," Dr. Nofech-Mozes said.

To identify novel pathological markers assessed using immunohistochemistry that could be used to determine which patients with DCIS are at high risk for invasive disease, Dr. Nofech-Mozes and colleagues reviewed 133 cases of pure DCIS treated with breast conserving surgery between 1982 and 2000.

"The idea was to identify a high risk group of patients who will actually benefit from the addition of radiotherapy and spare the radiotherapy for the majority of patients who are now getting it," she explained.

Patients were followed for a median of 8.91 years to determine who would develop invasive disease, and the investigators then assessed which pathological markers were most predictive of outcome.

In her poster presentation today, Dr. Nofech-Mozes said that in the area of DCIS, this study represents a large sample size. The follow-up period was also long enough to capture the majority of cases of invasive carcinoma that would occur in this cohort of patients, she said.

Among the 9 pathological markers they investigated, the researchers found the presence of 1 to be predictive of invasive disease: HER2/neu.

"This is the same marker that is targeted by herceptin [trastuzumab]," she said.

She also said that if the findings of this study are true, then each patient with DCIS should be tested for HER2/neu routinely. "It may be that these patients should be targeted with molecular therapy like Herceptin somewhere down the road. But this must be confirmed in a larger study."


[Presentation title: Molecular Markers for Invasive Recurrence in DCIS. Poster 72]

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