Circulating cancer cells (CCC) in breast cancer (BC) patients

Abstract

504 Background: Numbers and characterization of CCC may provide information relevant to prognosis and treatment of cancer patients (Pts.). We conducted a blood sampling study in pts. with histologically confirmed BC to assess for presence of CCC. Methods: Approximately 15 ml of venous blood were collected (before systemic therapy and periodically thereafter) and processed with a negative selection procedure using double-gradient centrifugation and magnetic cell sorting to remove RBC and WBC. The cells were stained with anti-pancytokeratin-FITC cocktail and DAPI (DNA stain). Digital images of FITC-positive cells were acquired with a fluorescence microscope for enumeration of CCC. Cells from 21 pts. were also stained simultaneously with labeled Trastuzumab antibody to quantify the HER-2/neu expression relative to a fluorescence standard. Results: 74 pts were accrued and 203 blood samples were drawn; median number of samples drawn per patient was 3 (1–5). Patient characteristics: median age 52 (32–84), race Caucasian -33, African American - 38, Asian-3. Nine pts. were stage I (0-positive for CCC), 16 stage II (6 -positive), 18 stage III (5-postive), 31 stage IV (25-positive). Mean number of CCC per sample was 62, range (1–1283), stage II and III 4, range (1–37), stage IV 76, range (1–1283). Minimum of 5 CCC per sample were needed to assess HER-2/neu receptor expression as compared with strongly HER-2/neu positive control cell line SKBR-3. Eight pts. had sufficient number of CCC to test for HER-2/neu expression. In 5 pts. the CCC and tumor data concurred and were negative, 1 patient was negative by CCC but tumor measured 3+ by IHC and in 2 pts. CCC were HER-/neu positive but tumor was not tested. Conclusions: CCC are related to presence of distant metastasis; but pts. with stage II and III disease may have CCC, the prognostic significance of which is unclear. CCC numbers ranged from 1 to several hundred per draw and fluctuated in the same patient depending on the response to systemic therapy. HER-2/neu expression could be quantified in individual CCC; in most cases CCC and primary tumor data concurred, however some exceptions were noted. Supported in part by NCI SBIR grant to CCC Diagnostics. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration CCC Diagnostics LLC CCC Diagnostics LLC CCC Diagnostics