Detecting cancer cells in the blood stream as means to predict recurrence

The present study evaluated whether the presence of cancer cells in the blood stream predicts a worse prognosis in women with operable breast cancer. The main finding was that progression-free survival (time before cancer progression) and overall survival were lower if circulating cancer cells were detected in the blood.

Detection of tumor cells in the blood (‘circulating’) is a relatively new technique which may help identify high risk groups among breast cancer patients. The test is performed by drawing a small quantity of blood (7.5 ml). It is hypothesized that these microscopic cells are responsible for cancer recurrence and spread to other organs. Previous studies revealed that around 20% of breast cancer patients may have tumor cells in the blood stream in the early stages of the disease.

The present study included 302 patients (with stage 1-3 breast cancer) undergoing surgery only (either partial or total mastectomy) to treat breast cancer. Participants did not receive previous chemotherapy. 7.5 ml of blood was collected from each patient to be analyzed for the presence of cancer cells. 24% of the patients had at least one circulating tumor cell in the blood sample, while 5% had three or more. After an average follow-up of 35 months, progression-free survival (time before cancer progress or reoccur) was lower in patients with circulating tumor cells. Overall survival was also decreased in the presence of circulating cancer cells. These results were proportional to the number of tumor cells found in the blood sample.

The findings suggest that some patients have a higher risk of cancer recurrence which is not related to the cancer stage. By detecting circulating tumor cells in the blood stream, these patients may receive different chemotherapy regimens to improve their survival and lower the risk of cancer recurrence.

Larger studies are still needed to see if this test will indeed improve breast cancer prognosis.