In multivariate Cox regression models of the effects of time-dependent covariates on progression, the covariates of metastatic tumor subtype, CTC count ≥5, and CTC expression of FGFR1 remained significant as independent prognostic factors (Table 2 and Table S2), although in an alternate multivariate model including metastatic tumor subtype, CTC count, and KRT7 (without FGFR1), KRT7 was significant (p = 0.0227) but not as strong as FGFR1 (not shown). Here, FGFR1 is linked to metastatic neoplasm.