Expression profile of CTC and corresponding tumors in primary breast cancer patients

538

Background: The target of adjuvant therapy in breast cancer is minimal residual disease (MRD). However, treatment decisions are based on expression of predictive markers (ER; PR, HER-2) of the primary tumor. Based on current studies, presence of MRD may be reflected by the detection of circulating tumor cells (CTC). Therefore, the aim of the study was to characterize CTC by multiplex-PCR for the expression of HER-2, ER, and PR and compare the expression profiles of CTCs with those of the corresponding primary tumors. Methods: CTC from blood of 431 patients with primary breast cancer were analyzed for EpCAM, MUC1, and HER-2 transcripts with the AdnaTest BreastCancer (AdnaGen AG, Germany). A blood samples was CTC positive when at least one of the markers was detected. Expression of the ER and PR receptor was assessed in an additional RT-PCR. The ER, PR and HER2 receptor status of the primary tumors was determined by immunohistochemistry. The DAKO-Score for the expression of HER-2 was determined with the HercepTest. Results: The overall detection rate for CTC was 13% (58/431 patients) with the expression rates of 38% for HER-2 (22/58 patients), 25% for ER (12/48) and 4% for PR (2/48), respectively. ER positivity of the primary tumor was demonstrated in 45/58 (78%) of these patients, PR positivity in 41/58 (71%) patients and HER-2 in 9/58 (16%) patients, respectively. The concordance rate between ER, PR, and HER-2 status of CTCs and the primary tumor was 29%, 25%, and 53%, respectively Interestingly, the spread of CTC was mostly found in triple negative tumors (p = 0.01) and CTC in general were mostly found to be triple-negative regardless of the ER, PR, and HER-2 status of the primary tumor. Conclusions: Since the expression profile between CTC and the primary tumor differs, the consequence for the selection of adjuvant treatment targeting minimal residual disease has to be further evaluated in clinical trials.

No significant financial relationships to disclose.

Estrogen receptor (ER) status of disseminated tumor cells in the bone marrow of breast cancer patients

21013

Background: The presence of disseminated tumor cells (DTC) in bone marrow (BM) of primary breast cancer patients is associated with poor prognosis. These patients may benefit from adjuvant endocrine therapy since cytotoxic agents are not able to completely eliminate DTCs as previously shown. Only patients with hormone receptor positive breast cancer are eligible for hormonal treatment. The ERa status is routinely defined in primary tumor tissue. However, the ERa status of DTC may differ compared to the primary tumor. Therefore, the aims of this study were (1) to determine the ERa status of DTC in BM of breast cancer patients, (2) and to compare the ERa status of DTC and corresponding primary tumors. Methods: BM aspirates from 251 primary breast cancer patients were included into the study. A double immunofluorescence staining procedure was established for the identification of cytokeratin-positive (CK)/ERa positive cells. ERa status of the primary tumor was immunohistochemically assessed using the same antibody against ERa. Results: In 105 of 251 (42%) breast cancer patients CK-positive cells could be detected in BM. The number of detected cells ranged between 1 and 13 / cells per 2*106 mononuclear cells. Disseminated tumor cells demonstrated ERa positivity in 13 (12%) of these 105 patients. The ERa expression on DTC was heterogeneous in 10 of 13 (79%) patients. Concordance rate of ERa status between primary tumor and DTC was 27%. Only 11 of 83 patients with ER a positive tumors had also ERa positives DTC. Conclusions: (1)The hormone receptor status between primary tumor and corresponding DTC is disconcordant. (2)This discrepancy may explain the rate of non-responders to adjuvant endocrine therapy despite ER-positive primary tumors. (3)These patients may benefit from adjuvant therapy regimens based on antibody strategies or bisphosphonates.

No significant financial relationships to disclose.