ECCO: Circulating Tumor Cells May Aid in Breast Cancer Prognosis

BARCELONA, Sept. 26 -- Monitoring circulating tumor cells in women with breast cancer may be help guide treatment and refine prognoses, according to preliminary data from German investigators.

They detected more than one circulating tumor cell per 20 mL of blood before initiation of chemotherapy in 10% of breast cancer patients they studied and at least two cells per 20 mL in 5% of the women, Julia Jckstock, M.D., of the University of Munich, and colleagues, said at the European Cancer Conference.

That finding, she said, was of interest because the concentrations of circulating tumor cells did not correlate with other well-recognized prognostic breast cancer factors such as tumor size, grade, estrogen-receptor status, or HER-2 status.

Moreover, when Dr. Jckstock compared baseline blood samples from 1,767 node-positive or high-risk node-negative breast cancer patients with blood taken from 852 of those women after chemotherapy, 10% of the women who were circulating tumor cell positive before treatment remained positive after treatment.

At the same time, 7% of the women who had no evidence of circulating tumor cells before chemotherapy, had positive circulating tumor cell results following treatment.

Circulating tumor cells are a common finding in women with metastatic breast cancer, she said, which led her to theorize that "the persistence of circulating tumor cells after chemotherapy treatment is likely to be predictive of the likelihood of recurrence of cancer in these patients."

But she cautioned that the findings were very preliminary and it will require years of follow-up to confirm this observation.

If confirmed, Dr. Jckstock said that blood tests for circulating tumor cells would not only be a "simple way of monitoring chemotherapy outcome," but could allow clinicians to better target chemotherapy regimens. Additionally, for women whose circulating tumor cell tests suggest an optimal response to therapy "we could reduce the length of treatment and use less aggressive therapies, thus sparing unpleasant side effects," she said.