Relationship between overall survival outcome and serum free light- chain measurements. (A) Comparison of OS between patients with an abnormal FLC (κ/λ) ratio to those with a normal ratio. The median OS for the 86 patients with a normal κ/λ FLC ratio (no clonal excess of light chain) was 63.6 months (95% confidence interval[CI]; 39, 92) compared with 16.2 months (95% CI; 12, 19) for the remaining 644 patients (P < .001). (B) Comparison of OS from diagnosis between patients with a high dFLC using the same cutoff for κ-AL and λ-AL patients (19.6 mg/dL). The median OS for patients with a high dFLC was 10.1 months (95% CI; 7, 13) compared with 38.2 months (95% CI; 29, 51) for those with a low dFLC (P < .001). (C) Comparison of OS from diagnosis between patients with a high dFLC using different cutoffs (individual median values) for κ-AL (29.4 mg/dL) and λ-AL patients (18.2 mg/dL) and low dFLC. The median OS among patients with a high dFLC was 10.9 months (95% CI; 8, 13) compared with 37.1 months (95% CI; 27, 47; P < .001).