P5-14-24: The Long Term Prognostic Impact of Real-Time Quantitative RT-PCR Detection of Cytokeratin 19 mRNA in Preoperative Bone Marrow Aspirates of Early Breast Cancer Patients.

Abstract

Abstract Purpose: Several studies have evaluated the prognostic effect of bone marrow micrometastases at the time of surgery in early breast cancer, but few studies have long term outcome data. We report here a cohort with more than ten years follow-up. Materials and methods: 131 patients with primary operable invasive breast cancer were enrolled in the protocol from February 1998 to September 1999. Bone marrow aspirates, obtained from the iliac crest or the sternum, were analyzed with real-time quantitative reverse-transcription polymerase chain reaction (RT-PCR) for the presence of cytokeratin 19 (CK19) mRNA. All patients received standard therapy and follow-up. After a median follow-up of 133 months, data about disease recurrence (invasive disease free survival, IDFS) and survival (breast cancer specific survival (BCSS) and overall survival (OS)) were collected. A control group consisted of archived cDNA samples from 38 patients with hematological malignant antecedents in complete remission and without known gene arrangements. The upper limit of the 95% confidence interval of the level of CK19 positive cells is this group was used as cut-off (260 cytokeratin 19+ cells / 5 × 106 leucocytes) to determine bone marrow status in breast cancer patients. Results: 69 bone marrow samples from breast cancer patients (52,7 %) were considered CK19 positive. IDFS was 60.9 % and 79 % for CK19+ and CK19- patients, respectively (log-rank p-value = 0,036). When CK19 was evaluated as a continuous variable, IDFS also correlated significantly with the level of CK19 mRNA in bone marrow aspirates (p-value = 0,019). Except for lymph node status (ANOVA linear regression p-value = 0.022), there was no significant correlation between the level of CK19+ cells in the bone marrow and classical prognostic factors (pathological tumor stage, tumor size, differentiation grade, hormonal receptor status). In multivariate Cox-regression analysis correcting for tumor size, differentiation grade, lymph node status, hormone receptor status, tumor stage and treatment modalities (surgical procedure, chemotherapy, radiotherapy and antihormonal therapy), the CK19 bone marrow status still was a significant predictor of IDFS. (p-value = 0.042) Differences in BCSS (78 % of CK19 + patients and 84 % of CK19 — patients) and OS (75 % in CK 19 + patients and 74 % in CK 19 — patients) were not statistically significant. (log rank p-values 0.087 and 0.883, respectively). Conclusion: This study demonstrates the long term (>ten years) prognostic effect of CK19 mRNA detection with RT-PCR in the bone marrow of operable breast cancer patients. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-14-24.