P4-06-02: Microscopic Disease in Blood and Bone Marrow Predicts Survival in Early Stage Breast Cancer.
Authors: Lucci A , Krishnamurthy S , Lodhi A , Bhattacharyya A , Hall C , Anderson A , Bedrosian I , Singh B , Kuerer H 
Published: June 2012

Background

Disseminated tumor cells (DTCs) in the bone marrow have been identified in 30% of stage I - III breast cancer (BC) patients and predict survival. Circulating tumor cells (CTCs) in the blood predict outcome in metastatic BC, but their prognostic significance in primary BC is unclear. This study determined whether: 1) DTCs and CTCs could be identified in significant numbers of non-metastatic BC patients and 2) if these cells predict relapse-free (RFS) and overall survival (OS).

Methods: Clinical stage I-III BC patients seen at a single tertiary cancer center provided informed consent to participate in an IRB-approved study involving collection of blood (7.5 ml x 2 tubes) and bone marrow (10 ml from bilateral iliac crests), and at the time of surgery for their primary BC. DTCs were assessed using an anti-cytokeratin antibody cocktail (MNF 116, CK 8,18, and 19, CAM 5.2, and AE1/AE3) following ficoll enrichment and cytospin. A positive result for DTCs was defined by presence of one or more CK-positive cells meeting morphologic criteria for malignancy. CTCs were detected using the Cell SearchTM system. A positive result was defined as the presence of one or more cells per 7.5 ml blood since a threshold for positivity has not been established in non-metastatic BC. Statistical analyses used chi-square and Fischer's exact test.

Results: We prospectively evaluated 313 patients. Mean age was 53 years, and median follow-up was 32 months. Forty-two percent of patients (131) had T1 tumors, 36% (112) T2, 10% (30) T3, and 13% (40) had T4 disease. Forty-five percent of patients (141/312) had positive lymph nodes. DTCs were identified in 29% (91/313) and CTCs in 25% (79/313) of all patients. Seven percent (21/313) of patients had both DTCs and CTCs. In the overall cohort, 26 (8%) patients relapsed and 15 (5%) died. Ten percent (9/91) of DTC positive patients died compared to 3% (6/222) of those who did not have DTCs (p=0.01). Similarly, 6% (7/79) of those who had CTCs died compared to 3% (8/234) of those who did not (p=0.03). Fifteen percent (12/79) of CTC positive patents relapsed compared to 6% (14/234, P=0.01) of those who were CTC negative. Simultaneous presence of DTCs and CTCs was a strong predictor of RFS (log rank p=0.030, HR= 2.8, 95% C.I. 1.20- 8.10) as well as OS (log rank p=0.026, HR= 3.66, 95% C.I. 1.03- 13.00) at 2 years. Combined presence of DTCs and CTCs was a predictor of outcome and these findings persisted after adjusting for variables including hormone receptor status, HER2 status, primary tumor size, grade, and preoperative lymph node status. There was no significant correlation between DTCs and/or CTCs with other primary tumor characteristics.

Conclusions: Circulating and disseminated tumor cells can be identified in a significant number of non-metastatic breast cancer patients. Both CTCs and DTCs predicted outcome, and their combined presence was an independent predictor of survival.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-06-02.