The survival benefit of neoadjuvant chemotherapy for resectable colorectal liver metastases with high tumor burden score

Background The indications for neoadjuvant chemotherapy (NAC) in resectable colorectal liver metastases (CRLMs) remain unclear. Tumor burden score (TBS) is a prognostic tool based on tumor size and number of tumors. However, its utility in the NAC setting for initially resectable CRLM has never been investigated. Methods TBS is a distance from the origin on a Cartesian plane to the coordinates (x,y) = (tumor size in centimeter, number of tumors). TBS < 3 was defined as "TBS-low", whereas TBS >= 3 as "TBS-high". Between 2008 and 2018, 102 patients who underwent hepatectomy for resectable CRLM were retrospectively analyzed using the Kaplan-Meier method and Cox proportional hazards regression models. Results Among the TBS-low (n = 46) and TBS-high (n = 56) groups, baseline patient characteristics were mostly similar except for TBS-related parameters. NAC was more frequently administered in the TBS-high group (p = 0.038). The overall survival (OS) rates were similar between the two groups. Subgroup analysis showed that NAC was associated with non-significantly improved 5-year OS in the TBS-high group [76.1% with NAC and 54.9% without NAC (p = 0.093)]. In multivariate analysis, NAC was an independent prognostic factor for favorable OS only in the TBS-high group, while adjuvant chemotherapy (AC) was associated with improved OS only in the TBS-low group. Conclusion In patients with resectable CRLM, the TBS-high population had a survival benefit from NAC, while the TBS-low population benefited from AC. TBS may serve as an indicator for patients who will benefit from NAC.