Response to Faitot et al “Two-stage Hepatectomy Versus 1-Stage Resection Combined With Radiofrequency for Bilobar Colorectal Metastases: A Case-matched Analysis of Surgical and Oncological Outcomes”

Parenchymal sparing surgery brings treatment of colorectal liver metastases into the precision medicine era

The treatment of advanced colorectal liver metastases (CRLMs) follows the biphasic pattern characteristic of oncological surgery. A phase of escalation-the therapeutic aggressiveness-is followed by a phase of de-escalation aimed at decreasing the morbidity, while preserving the gains in survival. From a maximum of three lesions, the rule no longer limits the number, provided the intervention does not cause lethal liver failure. Technically feasible non-anatomical resections, two-stage hepatectomies, portal vein obliteration and so forth, have pushed the boundaries of surgery far. However, the impact and the biology of metastatic processes have been long ignored. Parenchymal sparing surgery (PSS) is a de-escalation strategy that targets only metastasis by minimising the risk of stimulating tumour growth, while enabling iterative interventions. Reducing the loss of healthy parenchyma increases the tolerance of the liver to interval chemotherapy. Technically, PSS could use any type of hepatectomy, providing it is centred on the metastatic load alongside intraoperative ablation. The PSS concept sometimes wrongly comes across as a debate between minor versus major hepatectomies. Hence, we propose a clear definition, both quantitative and qualitative, of what PSS is and what it is not. Conversely, the degree of selectivity of PSS as a percentage of the volume of resected metastases versus the volume of total liver removed has not been stopped to date and should be the subject of prospective studies. Ultimately, the treatment of advanced CRLMs, of which PSS is a part, needs to be personalised by the multidisciplinary team by adapting its response to each new recurrence.

Parenchymal sparing surgery for colorectal liver metastases: The need for a common definition

BACKGROUND

The definition of parenchymal sparing surgery (PSS) for colorectal liver metastases (CRLM) diverges requiring a clarification of the concept.

METHOD

A consecutive series of patients were treated by PSS for their CRLMs, either by resection or intra-operative ablation (IOA), whenever possible a one-stage surgery and minimal usage of portal vein embolization. Post-operative complications were the primary endpoint with a special focus on post-operative liver failure.

RESULTS

Three hundred and eighty-seven patients underwent a PSS out of which 328 patients received a median of 9 pre-operative cycles of chemotherapy. One hundred and twenty-eight patients had a major resection, combined with IOA in 137 patients and IOA alone in 50 cases. The 5yr-overall survival was 50.3%. There was no difference in post-operative complications between minor and major resections, validating our PSS definition based on the Tumor burden/Healthy liver ratio and not just the retrieved volume.

CONCLUSIONS

PSS is defined as a high ratio of tumoral burden per specimen retrieved while favoring one-stage surgery approach. Our series, using combined resections and IOAs, matches this definition well. Furthermore, complications were correlated neither to chemotherapy nor to liver-induced toxicities, contrary to extended hepatectomies.