The prognostic value of circulating tumor cells in patients with melanoma: a systematic review and meta-analysis.
BACKGROUND
The detection of circulating tumor cells (CTC) in patients with melanoma represents an appealing prognostic tool, but no consensus exists on this topic. We aimed to comprehensively and quantitatively summarize the evidence for the use of CTC to predict patients' clinical outcome.


METHODS
Fifty-three studies enrolling 5,433 patients were reviewed. Correlation of CTC status with tumor-node-metastasis disease stage and patients' overall (OS) and progression-free (PFS) survival was assessed by means of association statistics and meta-analysis, respectively.


RESULTS
CTC status correlated with both tumor-node-metastasis stage (stage I, 32%; stage II, 41.7%; stage III, 41.1%; stage IV, 47.4%; P(trend) < 0.0001) and survival (OS: hazard ratio, 2.42; 95% confidence interval, 1.7-3.45, P < 0.0001; PFS: hazard ratio, 2.45; 95% confidence interval, 1.78-3.38; P < 0.0001). However, statistical heterogeneity was significant for both OS and PFS, likely underscoring the wide variability in study design. Furthermore, CTC positivity rates in early stages were higher and in the metastatic setting were lower than expected, which indicates an unsatisfactory accuracy of currently available CTC detection assays.


CONCLUSIONS
Our findings suggest that CTC might have a clinically valuable prognostic power in patients with melanoma. However, the heterogeneity of the studies thus far published warrants caution not to overestimate the favorable results of pooled data.
Mocellin
Simone
S
Department of Oncological and Surgical Sciences, Surgery Branch, University of Padova, Padua, Italy. mocellins@hotmail.com
Hoon
Dave
D
Ambrosi
Alessandro
A
Nitti
Donato
D
Rossi
Carlo Riccardo
CR
D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018572:Disease-Free Survival; D008207:Lymphatic Metastasis; D008545:Melanoma / Q000097:blood / Q000473:pathology; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000473:pathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016019:Survival Analysis