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.