Clinical relevance of circulating CK-19 mRNA-positive cells detected during the period of adjuvant tamoxifen treatment in patients with early breast cancer

Abstract

10534 Background: To evaluate the effect of adjuvant treatment with tamoxifen on the CK-19 mRNA+ circulating tumor cells (CTCs) in patients with early-stage breast cancer. Methods: CTCs were prospectively and longitudinally detected using a specific real-time PCR for CK-19 mRNA in 119 patients with estrogen and/or progesterone receptor-positive tumors during the period of tamoxifen administration. Results: Twenty-two (18.5%) patients had detectable CK-19 mRNA+ CTCs after the completion of adjuvant chemotherapy and in 15 (68.2%) of them adjuvant tamoxifen could not eliminate these cells (persistently positive). In 68 (57.1%) patients no CK-19 mRNA+ CTCs could be detected throughout the follow up period (persistently negative). Seven (46.7%) of the 15 persistently positive and six (8.8%) of the 68 persistently negative patients developed disease recurrence (p=0.00026). Persistence of CK-19 mRNA+ CTCs was associated with a significantly shorter median disease-free interval (p=0.0001) and overall survival (0.0005). Multivariate analysis revealed that the detection of CK-19 mRNA+ CTCs during the administration of tamoxifen was associated with an increased risk of relapse (HR=22.318, p=0.00006) and death (HR=13.954, p< 0.00001). Conclusions: The detection of CK-19 mRNA+ CTCs throughout the period of adjuvant tamoxifen treatment is an independent poor prognostic factor in patients with early breast cancer. No significant financial relationships to disclose.