Mao R, et al. - This study was conducted to ascertain the impact of surgical margin status on overall survival (OS) and recurrence pattern stratified by tumor burden. Researchers identified negative margin as an important determinant of survival. In patients with low tumor burden, the impact of positive margins was more pronounced.

Methods

• Researchers collected data from patients undergoing resection for colorectal liver metastases (CRLM).
• In this study, tumor burden was calculated according to a newly proposed Tumor Burden Score (TBS) system, defined as the distance from the origin on a Cartesian plane that incorporated maximum tumor size and number of liver lesions.
• They divided patients into low tumor burden group and high tumor burden group accordingly, and examined the impact of resection margin on overall survival.

Results

• Researchers identified a total of 286 patients.
• Among these, they observed R1 resection in 88 patients.
• For the entire cohort, the median TBS was 3.84.
• More advanced disease and more complex resections characterized the metastases in the R1 group.
• In comparison to an R0 resection, an R1 resection resulted in a lower 5-year overall survival rate (46.8% vs. 22.1%, p=0.001).
• In multivariate analysis, R1 resection (p=0.03), high TBS (p=0.002), lymph nodes metastases (p=0.003) and lymphovascular invasion (p=0.03) of the primary colorectal tumor were identified as the factors independently associated with worse survival.
• In patients with low TBS, the survival benefit associated with negative margins was greater (55.7% vs. 21.7%, p=0.021) than in patients with high TBS (31.8% vs. 24.5%, p=0.116).
• They noticed that R1 resection was associated with an increased true margin recurrence rate in patients with low TBS (32.3% vs. 13.4%; p=0.014) and an increased risk of new intrahepatic metastases in patients with high TBS (43.9% vs. 26.7%; p=0.034).