Circulating tumor cell (CTC) counts prior to neoadjuvant chemotherapy for early-stage breast cancer predict overall survival (OS), distant disease-free survival (DDFS), and locoregional recurrence-free survival (LRFI), according to findings from a meta-analysis presented at the 2016 San Antonio Breast Cancer Symposium.1
“Post-neoadjuvant survival does not exclusively rely on breast cancer characteristics and pCR,” said François-Clément Bidard, MD, PhD, of the Institut Curie in Paris, France. “CTC complements but does not duplicate usual prognostic factors.”
CTCs seed distant metastasis, Dr Bidard noted. They are prognostic before and during therapy for patients with metastatic breast cancer, and prognostic before adjuvant therapy for patients with non-metastatic breast cancer, he said.
But in the neoadjuvant setting, study findings have been inconsistent.
To evaluate the prognostic value of CTCs for overall survival in the neoadjuvant setting, Dr Bidard and colleagues evaluated data from published and unpublished research, identifying studies of patients with early-stage breast cancers treated with neoadjuvant chemotherapy, for whom survival data were available, and for whom CTCs had been counted using the CellSearch® system.
Data for 2156 patients from 21 studies and 16 centers were included in the meta-analysis. Data represented CTC counts for 1574 patients from before they began neoadjuvant chemotherapy and from 290 patients after chemotherapy, and 1200 patients from before surgery and 285 patients after surgery, he reported.
Baseline CTC detection before neoadjuvant chemotherapy predicted OS (stratified P < 0.0001), Dr Bidard reported. No interaction was detected for tumor subtype.
“Not only is CTC predictive of OS but the CTC count correlates with OS hazard ratios [HRs],” he pointed out: patients in whom 5 or more CTCs were detected per 7.5mL had an OS HR of 6.25 (95% CI: 4.34-9.09) compared to an OS HR of 2.63 (95% CI: 1.42-4.54) for those in whom 2 CTCs were detected.
Findings were similar for the relationship between baseline (pre-chemotherapy) CTCs and both distant disease-free survival and locoregional relapse-free survival.
Detected CTCs decreased during neoadjuvant chemotherapy (from 25% of patients but did not correlate with pathological complete response (pCR), he reported.
- Bidard FC, Michiels S, Mueller V, et al. IMENEO: International MEta-analysis of circulating tumor cell detection in early breast cancer patients treated by NEOadjuvant chemotherapy Paper presented at: 39th San Antonio Breast Cancer Symposium; Dec 2016; San Antonio, TX.