FCF1 and neoplasm: We also explored the clinical significance of each individual gene of our CTC-specific signature with respect to the tumor features, and we observed that TFF1 was associated with the tumor proliferation index and with the histological subtype and was more frequently detected in M+ compared to M0 cases, that also TFF3 detection frequency was higher in M+ cases, and that FCF1 was associated to the histological subtype (Supplementary Table S3).