Neoadjuvant chemotherapy weakens the prognostic value of the pathological tumor burden score for colorectal cancer liver metastases.

Background: The pathological tumor burden score (TBS) has been proven to be a better risk stratification tool for liver metastasis of colorectal cancer than the traditional clinical risk score (CRS). The aim of this study was to evaluate the prognostic value of the pathological tumor burden score in patients with or without neoadjuvant chemotherapy (NAC).

Methods: A total of 348 patients with colorectal liver metastases (CRLM) who underwent curative hepatic resection were retrospectively enrolled from September 1999 to December 2016. Univariable and multivariable Cox regression analyses were conducted to identify the independent predictors of prognosis. Kaplan-Meier curves and log-rank tests were used to determine whether TBS has enough discriminatory ability under certain grouping.

Results: Patients who received NAC had a higher median TBS than patients who did not receive NAC (4.07 vs. 2.69, P < 0.001). Among patients who did not receive NAC, those with TBS > 3 showed a significantly worse 3-year RFS (41.1% vs. 63.6%, P < 0.001) and 3-year OS rate (73.3% vs. 84.1%, P = 0.003) than those with TBS ≤ 3. Among the patients who received NAC, those with TBS ≤ 3 or TBS > 3 showed comparable 3-year RFS (33.3% vs. 26.4%, P = 0.400) and 3-year OS rates (76.5% vs. 58.2%, P = 0.064) to those who did not. Regardless of the regimen and response to NAC, there was no significant difference about 3-year RFS and 3-year OS rates between the TBS ≤ 3 and TBS > 3 groups.

Conclusion: Pathological TBS can be applied to predict the RFS and OS of patients suffering from CRLM who did not receive NAC. However, pathological TBS might not be regard as prognosis in patients who did receive NAC.