Purpose: We aimed to investigate the prognostic role of baseline and longitudinal levels of neutrophil-to-lymphocyte ratio (NLR) in patients with metastatic colorectal cancer (mCRC) treated with chemotherapy + bevacizumab (CT + B) or chemotherapy only. Additionally, we investigated whether treatment outcomes were mediated by the longitudinal biomarker.
Methods: Data from an Italian randomized phase III trial were used. The main end point was progression-free survival (PFS). To address research questions, a series of joint models of longitudinal and survival data were specified, and the direct and indirect treatment effects were quantified.
Results: Data for 239 patients, 113 (47.3%) treated with CT + B and 126 (52.7%) with CT only, were included in the analyses. The effect of NLR seemed to be mediated by the longitudinal trajectory of the biomarker. Only in the patient subgroup treated with CT + B, the baseline NLR retained a direct effect on PFS. Regarding the effect of treatment on PFS, two scenarios were observed. In the subgroup of patients with low baseline, NLR bevacizumab showed a direct protective effect only (hazard ratio [HR], 0.66 [95% CI, 0.45 to 0.98]), whereas in the subgroup with high baseline NLR, there was evidence for an adverse direct effect (HR, 1.63 [95% CI, 1.03 to 2.57]) and a protective indirect-which is mediated by the longitudinal biomarker-effect (HR, 0.71 [95% CI, 0.55 to 0.90]).
Conclusion: In our study, inflammatory indexes collected longitudinally showed a significant adverse prognostic role, thus suggesting the collection and use of such data for better clinical decision making. In the specific setting, we considered this is particularly important as the treatment effect seemed to be modified by both the baseline and longitudinal inflammation statuses. However, further research is needed to understand the possible factors underlying these results.
Trial registration: ClinicalTrials.gov NCT01878422.