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Abstract Background Presence of disseminated tumor cells (DTCs) in bone marrow (BM) after completion of systemic adjuvant treatment predicts reduced survival in breast cancer. The present study explores the use of DTCs to identify adjuvant insufficiently treated patients to be offered secondary adjuvant treatment intervention, and as a surrogate marker for therapy response. Methods A total of 1121 patients with pN1-3 or pT1c/T2G2-3pN0-status were enrolled. All had completed primary surgery and received 6 cycles of anthracycline-containing chemotherapy. BM-aspiration was performed 8-12 weeks after chemotherapy (BM1), followed by a second BM-aspiration 6 months later (BM2). DTC-status was determined by morphological evaluation of immunocytochemically detected cytokeratin-positive cells. If DTCs were present at BM2, docetaxel (100 mg/m2, 3qw, 6 courses) was administered, followed by DTC-analysis 1 month (BM3) and 13 months (BM4) after the last docetaxel infusion. Results Clinical follow-up (FU) is still ongoing. Here, the descriptive data from the study are presented. Of 1085 patients with a reported DTC result at both BM1 and BM2, 94 patients (8.7%) were BM1 positive and 83 (7.6%) were BM2 positive. The concordance between BM1 and BM2 was 86.5%. Both at BM1 and BM2 DTC-status was significantly associated with lobular carcinomas (p = 0.02 and p = 0.03, respectively; chi-square). In addition, DTC-status at BM2 was also associated with pN-status (p = 0.009) and pT-status (p = 0.03). At BM1 28.8% and 12.8% of the DTC-positive patients had ≥2 DTCs and ≥3 DTCs, respectively. At BM2, the corresponding frequencies were 47.0% and 25.3%. Of 72 docetaxel-treated patients analyzed at BM3 and/or BM4, only 15 (20.8%) had persistent DTCs. Of 17 patients with ≥3 DTCs before docetaxel treatment, 12 patients turned negative after treatment (70.6%). The change to DTC-negativity was associated with the presence of ductal carcinoma (p = 0.009). Conclusions After docetaxel treatment, the majority of patients experienced disappearance of DTCs. As this is not a randomized trial, the results can be due to effects of adjuvant (docetaxel/endocrine/trastuzumab) treatment and/or limitations of the methodology. The clinical significance of these results awaits mature FU data, but indicates a possibility for clinical use of DTC-status as a residual disease-monitoring tool and as a surrogate marker of treatment response. Trial registration Clin Trials Gov NCT00248703

Background: Disseminated tumor cells (DTCs) have potential to predict the effect of adjuvant treatment. The purpose of this study was to compare two methods, reverse transcription quantitative PCR (RT-qPCR) and immunocytochemisty (ICC), for detecting breast cancer DTCs in bone marrow (BM) from early breast cancer patients., Methods: We investigated a subset (n = 313) of BM samples obtained from 271 early breast cancer patients in the "Secondary Adjuvant Taxotere Treatment" (SATT)-trial. All patients in this study had node positive or intermediate/high-risk node negative non-metastatic disease. The DTCs were detected by ICC using AE1-AE3 anti-cytokeratin monoclonal antibodies. Patients with DTCs detected in their BM by ICC after standard adjuvant fluorouracil, cyclophosphamide, epirubicin (FEC) chemotherapy were offered docetaxel treatment. For comparison, 5 × 106 mononuclear cells from the aliquoted BM samples were also analyzed by RT-qPCR using a multimarker (MM) assay based on the tumor cell mRNA markers keratin 19 (KRT19), mammaglobin A (hMAM), and TWIST1. In the MM-assay, a sample was defined as positive for DTCs if at least one of the mRNA markers was positive., Results: The MM RT-qPCR assay identified DTCs in 124 (40%) of the 313 BM samples compared with 23/313 (7%) of the samples analyzed by ICC. The concordance between the MM RT-qPCR and ICC was 61% (Kappa value = 0.04) and twelve of the BM samples were positive by both methods. By RT-qPCR, 46/313 (15%) samples were positive for KRT19, 97/313 (31%) for TWIST1, and 3/313 (1%) for hMAM mRNA. There were no statistically significant associations between the individual mRNA markers., Conclusion: The RT-qPCR based method demonstrated more DTC-positive samples than ICC. The relatively low concordance of positive DTC-status between the two different assessment methods suggests that they may be complementary. The clinical relevance of the methods will be evaluated based on future clinical outcome data., Trial Registration: ClinicalTrials.gov: NCT00248703.