Simplified prognostic model in patients with oxaliplatin-based or irinotecan-based first-line chemotherapy for metastatic colorectal cancer: a GERCOR study

Abstract

Background: The present study was done to establish a prognostic model for patients and trials using an oxaliplatin-based or irinotecan-based first-line chemotherapy in metastatic colorectal cancer.

Patients and methods: Eight hundred three patients treated with FOLFOX or FOLFIRI in three prospective trials were randomly separated into learning (n = 535) and validation (n = 268) samples. Eleven baseline variables were evaluated in univariate and multivariate analysis as prognostic factors for overall survival, and a prognostic score was developed.

Results: Independent prognostic factors identified in multivariate analysis for overall survival were performance status (PS) (p < .001), serum lactate dehydrogenase (LDH) (p < .001), and number of metastatic sites (p = .005). A prognostic score based on these three variables was found efficient (Harrell's C index 0.61). This new model was improved by selecting only PS and LDH (Harrell's C index 0.64). Three risk groups for death could be identified: a low-risk group (n = 184; median overall survival [OS] 29.8 months), an intermediate-risk group (n = 223; median OS 19.5 months), and a high-risk group (n = 128; median OS 13.9 months). Median survival for the low-, intermediate-, and high-risk groups were 26.8, 21.1, and 16.5 months, respectively, in the validation sample (Harrell's C index 0.63).

Conclusions: Serum LDH level was the main prognostic factor in predicting survival, followed by WHO PS. We identified three risk groups for death depending on these two baseline parameters. This simple prognostic model can be useful for clinician's use and patient stratification in future clinical trials.

Figure 1.

Overall survival according to independent prognostic factors in learning sample (A–C) and validation sample (D–F). (A): WHO PS (learning sample), (B): serum LDH level (learning sample), (C): number of metastatic sites (learning sample), (D): WHO PS (validation sample), (E): serum LDH level (validation sample), and (F): number of metastatic sites (validation sample). Abbreviations: LDH, lactate dehydrogenase; PS, performance status; WHO, World Health Organization.

Figure 2.

Survivals in high-, intermediate-, and low-risk groups in Köhne and GERCOR models (learning and validation samples). (A): Köhne model in learning sample, (B): GERCOR model in learning sample, (C): Köhne model in validation sample, and (D): GERCOR model in validation sample.

Figure 3.

GERCOR prognostic model. Abbreviations: CI, confidence interval; LDH, lactate dehydrogenase; OS, overall survival; PS performance status; ULN, upper limit of normal.