Breast cancer recurred in 114 patients, and 66 patients died. Being CTC-positive was a significant independent predictor for both disease-free and overall survival. Patients with one to four CTCs had an 88 percent increased risk of early breast cancer recurrence and a 91 percent increased risk of death from breast cancer, according to Rack.

Prognosis was worse in patients with five or more CTCs; these patients had a fourfold risk of cancer recurrence and a threefold risk for death from the disease.

"Our study suggests testing CTCs may prove to be important to help individualize therapy for early-stage breast cancer where no measurable tumor is present," she said. "Patients who seem to be at high risk due to CTC may benefit from additional treatment options, and those that don't have CTCs may be spared side effects of some treatments."

She added, however, that prospectively randomized trials are necessary to show an improvement of survival based on CTC diagnostics. Trials testing this notion are either ongoing or about to start in Europe and the United States, according to Rack.

SOURCE American Association for Cancer Research