Assessment of circulating tumor cells and serum markers for progression-free survival prediction in metastatic breast cancer : a prospective observational study
Menée sur 267 patientes atteintes d'un cancer métastatique du sein, cette étude compare les performances de divers marqueurs sanguins (cellules tumorales circulantes et marqueurs sériques) pour prédire la survie sans progression
INTRODUCTION:Circulating tumors cells (CTC) have been recently proposed as a new dynamic blood marker whose positivity at baseline is a prognostic factor and whose changes under treatment are correlated with progression-free survival (PFS) in metastatic breast cancer patients. However, serum markers levels are also used for the same purpose, and no clear comparison as been reported to date.METHODS:The IC 2006-04 enrolled prospectively 267 metastatic breast cancer patients treated by first line chemotherapy and confirmed that CTC levels are an independent prognostic factor for PFS and Overall survival (OS). A secondary pre-planned endpoint was to compare prospectively the positivity rates and the value of CTC (CellSearch(R)), of serum tumor markers (CEA, CA 15-3, CYFRA 21-1), and of serum non-tumor markers (LDH, ALP) at baseline and under treatment for PFS prediction, independently from the other known prognostic factors, using univariate analyses and concordance indexes.RESULTS:90% of patients had at least one elevated blood marker. Blood markers were correlated with poor performance status, high number of metastatic sites and with each other. In particular, CYFRA 21-1, usually used in lung cancer, was elevated in 65% of patients. 86% of patients had either CA 15-3 and/or CYFRA 21-1 elevated at baseline. Each serum marker was associated, when elevated at baseline, with a significantly shorter PFS. Serum marker changes during treatment, assessed either between baseline and week 3 or between baseline and week 6-9, were significantly associated with PFS, as reported for CTC. Concordance indexes comparison showed no clear superiority of any of the serum marker or CTC for PFS prediction.CONCLUSIONS:For the purpose of PFS prediction by measuring blood marker changes during treatment, currently available blood-derived markers (CTC and serum markers) had globally similar performances. Besides CEA and CA 15-3, CYFRA 21-1 is commonly elevated in metastatic breast cancer and has a strong prognostic value. Trial registration: NCT00898014
Breast Cancer Research , article en libre accès, 2011