Colorectal Cancer Liver Metastases: Is an R1 Hepatic Resection Accepted?

Abstract

Metastatic colorectal cancer is associated with a rather dismal 5-year overall survival. The liver is the most commonly affected organ. Improved 5-year survival rates after successful hepatic resections for metastases confined to the liver have been reported. Certainly, a hepatectomy that results in an incomplete tumor resection, in terms of leaving macroscopic residual tumor in the future liver remnant, is not associated with survival benefits. However, the prognostic implications of a microscopically positive surgical margin or a clear margin of less than 1 mm (R1) on pathology are debatable. Although it has been a field of extensive research, the relevant literature often reports contradictory results. The purpose of the present study was to define, assess the risk factors for, and, ultimately, analyze the effect that an R1 hepatic resection for colorectal cancer liver metastases might have on local recurrence rates and long-term prognosis by reviewing the relevant literature. Achieving an R0 hepatic resection, optimally with more than 1 mm of clear margin, should always be the goal. However, in the era of the aggressive multimodality treatment of liver metastatic colorectal cancer, an R1 resection might be the cost of increasing the pool of patients finally eligible for resection. The majority of literature reports have highlighted the detrimental effect of R1 resections on local recurrence and overall survival. However, there are indeed studies that degraded the prognostic handicap as a consequence of an R1 resection in selected patients and highlighted the presence of RAS mutations, the response to chemotherapy, and, in general, factors that reflect the biology of the disease as important, if not the determinant, prognostic factors. In these patients, the aggressive disease biology seems to outperform the resection margin status as a prognostic factor, and the recorded differences between R1 and R0 resections are equalized. Properly and accurately defining this patient group is a future challenge in the field of the surgical treatment of colorectal cancer liver metastases.

The Impact of KRAS Status on the Required Surgical Margin Width for Colorectal Liver Metastasis Resection

“…Several studies have assessed the required surgical margin width. Although a few studies have reported that the era of advances in chemotherapy and multimodal therapies may make R1 resection acceptable [ 12 ], R0 resection for CRLM is the gold standard in the world [ 3 , 23 , 24 ] and the “1 cm rule” has been widely adopted. A surgical margin of > 1 cm offers a low LRR and favorable prognosis in some studies [ 5 , 9 , 25 ]; however, sometimes a 1 cm resection margin is difficult to achieve due to a shortage of the remnant liver reserve and the location of the major intrahepatic vessels.…”

Colorectal Cancer Liver Metastasis—State-of-the-Art and Future Perspectives

“…In conclusion, R1 resections are associated with local recurrence and worse long-term results but are still a better option than no resection [200]. We believe that the future challenge in the field of surgical resection of CRLM is to integrate the disease biology in the resection margins.…”

“…In the literature, an R1 resection varies between an involved margin (width = 0 mm) or a margin width less than 1 mm, and the absence of a universally adopted definition can mislead the interpretation of different research results that reported R1 as a worse OS with significance as a predictor of survival [200]. Some concerns have equally been raised in relation to the margin width and the HGP since patients with non-desmoplastic HGP are at higher risk of a positive resection margin [182,201].…”