Abstract P2-10-25: Prognostic value of relative change in tumor marker CA 27.29 in early stage breast cancer – The SUCCESS trial

Background: MUC1 based tumor markers like CA27.29 (TM) in breast cancer are routinely used in metastatic disease as early marker for treatment efficacy. However, in early stage disease data is sparse. In this analysis, we looked at the impact of individual change in CA27.29 on prognosis instead of using a threshold. Methods: The SUCCESS Trial compares FEC-docetaxel (Doc) vs. FEC-Doc-Gemcitabine (Doc-G) regime and two vs. five year treatment with Zoledronat in 3754 patients (pts) with primary breast cancer (N+ or high risk N0). We measured CA27.29 after surgery but before chemotherapy (CHT) as baseline and compared it to CA27.29 levels 2 years thereafter with the ST AIA-PACK Ca27.29 reagent using MUC-1 for AIA-600II (Tosoh Bioscience, Tessenderlo, Belgium). Results: CA27.29 data is available of 2,015 pts. 119 pts (5.9%) had TM over the threshold of 32U/ml before CHT and 56 (2.8%) 2years thereafter. To examine the relative change of tumor marker, pts were divided into 3 groups: increase: change >=5 U/ml; stable: change = −5 U/ml. 123 (6.1%) pts had increasing (>=5 U/ml), 1419 (70.4%) had stable, 473 (23.5%) had decreasing TM levels from before CHT to 2 years thereafter. The majority of pts with increasing TM (86 pts; 69.9%) had levels below the usual threshold of 32U/ml at all times. Patients with an increase >=5 U/ml had an 81% increased risk for recurrence (HR = 1.810 [CI: 1.111–2.948]) and reduced overall survival (HR = 1.020 [CI: 1.004–1.037]). In the multivariate analysis taking into account tumor size, nodal status, grading, age, hormonal and HER2/neu receptor status increasing CA27.29 levels were an independent prognostic marker. Conclusions: An increase of the tumor marker CA27.29 2 years after CHT compared to pre-chemotherapy baseline was associated with a worse prognosis. By using this approach, more patients at risk for recurrence were detected than with the standard threshold approach. Therefore, the use of relative change could help to identify more patients at risk for relapse who might benefit from an intensified follow up. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-10-25.