Circulating tumor cells in adjuvant breast cancer patients

Abstract

667 Background: One of the first steps in metastasis is the ability of primary breast cancer cells to detach and invade the circulation. The presence of ≥5 circulating tumor cells (CTCs) in 7.5 mL blood from metastatic breast cancer patients predicts shorter progression-free and overall survival (M Christofanilli et al NEJM 351:781–791, 2004). The purpose of our study was to determine if CTCs were present in the blood of patients who had recently completed adjuvant chemotherapy. Methods: Blood was obtained from 33 breast cancer patients within 12 months after completing adjuvant chemotherapy. No patient had evidence of metastatic cancer on imaging. CTCs were immunomagnetically separated and fluorescently stained with the CellSearch Kit. Cells were classified using the CellSpotter Analyzer as CTCs if they stained positive for DAPI (nuclear dye), and cytokeratin 8, 18 and/or 19, and if they stained negative for the leukocyte-specific antibody CD45. Results: In a control group of 145 healthy females, 8 (5.5%) had 1 CTC/7.5 mL blood. In 199 patients with benign disease, 14 (7.0%) had 1 CTC/7.5 mL, and only 1 (0.5%) had 3 CTCs/7.5 mL detected in their blood. Of the 33 total patients in this study, 3 patients (9.1%) had ≥1 CTC/7.5 mL detected in their blood samples (one patient had 1 CTC in one 7.5 mL tube, and another patient had 2 CTCs in one 7.5 mL tube. The second 7.5 mL tube from both of these patients had no CTCs. The third patient had 1 CTC in three of the four 7.5 mL tubes tested). In the other 30 patients, no CTCs were detected (0/4 tubes in 16 patients; 0/2 tubes in 14 patients). In summary, CTCs were detected in 3/33 (9.1%) adjuvant breast cancer patients, 8/145 (5.5%) healthy controls, and 15/199 (7.5%) benign disease patients. There were no significant differences in the proportion of CTCs between these groups (p≥0.30, Fisher’s exact test). Of 6 patients with 3+ IHC for HER-2/neu in the primary tumor, 2 (33%) had CTCs in their blood. Conclusions: No significant difference in the proportion of CTCs detected was observed between breast cancer patients who recently completed adjuvant chemotherapy and the control groups. Patient accrual and follow-up in this study continues to determine if the presence of elevated CTCs is associated with early recurrence of the disease. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Immunicon