Tumor Cells in Blood May Indicate More Aggressive Breast Cancer

If patients with breast cancer have tumor cells circulating in the blood, they may have a more dangerous form of the disease, according to a study by researchers at The University of Texas M. D. Anderson Cancer Center.

The results could lead to more tailored treatment that would spare some patients from the most potent chemotherapy and its toxic side effects.

The study, led by Massimo Cristofanilli, M.D., assistant professor of medicine in the Department of Breast Medical Oncology, was published n the Proceedings for the 2003 Annual Meeting of the American Association of Cancer Research, found that women who have tumor cells circulating in the blood have reduced survival compared to those without circulating tumor cells.

Until recently, doctors have not been able to reliably isolate circulating tumor cells. Within the last few years, several methods have been developed to label tumor cells with antibodies that can then be measured precisely, identifying even one tumor cell in a vial of blood, says Cristofanilli. In the current study, the scientists used an automated system developed by Immunicon Corp., Huntington Valley, Pa.

"We know that invasion and metastasis are the most life threatening aspects of cancer," says Cristofanilli. "To metastasize, cancer cells must leave the site of the primary tumor, travel through the blood and proliferate in a new site. If we discovered in a newly diagnosed patient that tumor cells are already in the blood, we would be aware that we are dealing with a more aggressive cancer that may require more aggressive treatment."

In the study, Cristofanilli and his colleagues studied 41 patients who had just been diagnosed with metastatic breast cancer and were about to begin treatment at M. D. Anderson. The scientists found circulating tumor cells in 24 of the 42 patients.

The women who had no circulating tumor cells had a median survival of more than 24 months, while those who had more than three circulating tumor cells survived an average of 13.6 months. Patients with more than 50 cells circulating had a median survival of only 3.8 months. Even more, says Cristofanilli, the presence of cancer cells in the blood predicted prognosis more accurately than the site of metastatic disease or the presence of estrogen receptor on the tumor cells, the scientists said.

"The general consensus is that if a tumor is estrogen receptor positive, it is considered slower growing and less aggressive," says Cristofanilli. "Our study indicates that if cancer cells are present in the blood, the cancer may be more aggressive, regardless of estrogen receptor status."

However, he emphasizes that the study included a relatively small number of patients and a larger study is needed. In addition, he would like to study the correlation of circulating tumor cells to how patients respond to various types of treatments.

"If you look carefully, patients who are considered to have similar disease by standard clinical criteria, may in fact have tumors that have quite different biological characteristics," he says. "Some patients might do better, no matter what treatment they receive. I would like to see circulating tumor status used prospectively to group patients for future clinical trials."

The study was funded by Immunicon Corp.