Nodular Regenerative Hyperplasia in Patients Undergoing Liver Resection for Colorectal Metastases After Chemotherapy: Risk Factors, Preoperative Assessment and Clinical Impact.

Background: Nodular regenerative hyperplasia (NRH) is a severe form of chemotherapy-related liver injury (CALI) that may worsen the short-term outcome of liver resection (LR) for colorectal metastases (CRLM). The present study aimed to clarify the incidence, risk factors, preoperative assessment, and clinical impact of NRH.

Methods: Overall, 406 patients undergoing 478 LRs for CRLM after chemotherapy between 2000 and 2012 were studied. All resection specimens were reviewed. After Gomori staining, NRH was graded according to the Wanless score.

Results: NRH was diagnosed in 87 (18.2 %) patients, grades 2-3 in 14 (2.9 %) patients. At multivariate analysis, the prevalence of NRH was increased after oxaliplatin administration (21.4 vs. 8.4 %; p = 0.003), and reduced by the addition of bevacizumab (11.7 vs. 19.8 %; p = 0.020). Two parameters predicted the presence of NRH: the APRI score (AST to platelet ratio index: 25.5 % if >0.36 vs. 9.8 % if ≤0.36; p = 0.004), and the platelet count (63.6 % if <100 × 10(3)/mm(3) vs. 25.3 % if 100-200 × 10(3)/mm(3) vs. 11.9 % if >200 × 10(3)/mm(3); p = 0.032). Ninety-day mortality and liver failure rates were 0.6 and 3.6 %. NRH was an independent predictor of postoperative liver failure (9.2 % if present vs. 2.3 % if not present; p = 0.021). In patients with grades 2-3 NRH, the rate of liver failure was 14.3 %, 25.0 % after major hepatectomy. No other forms of CALI impacted short-term outcomes.

Conclusions: NRH was the most relevant form of CALI, increasing the risk of postoperative liver failure. Oxaliplatin increased the incidence of NRH, while bevacizumab decreased it. The APRI score and platelet count were useful tools for predicting NRH.