CEACAM5 and neoplasm: Clinically, and supported by correlation analysis of tumor and treatment variables (Figure 2A–D), an accurate surrogate for the in vitro fkill0 is thus obtained by estimating 〈σT,B〉 as:(2)fkill0~〈σT,B〉~σ=B,i·λ·ΔtCEAwhere λ=Nt is the frequency of chemotherapy cycles, i.e., number of cycles N per unit duration t of treatment; Δt is the duration of a single therapy cycle (≈46 h); and serum carcinoembryonic antigen (CEA) is the biomarker for total tumor burden, a surrogate for tumor size based on the correlation (Figure 2A).