Challenges and Opportunities for Precision Surgery for Colorectal Liver Metastases

Simple Summary Colorectal cancer is a common illness. It can spread to the liver in about a quarter of people with colorectal cancer, known as metastases. Previously, people with liver metastases did not survive for long. Thankfully, this is changing. As we understand more about the underlying causes and genetics of the disease, we can tailor treatments to patients on a more individual basis. Treatments like chemotherapy have made a difference in patients' survival, and now newer treatments like immunotherapy can have even greater benefits. Surgery is also changing, with more advanced techniques allowing for better recovery for patients and more aggressive surgery. It is important for surgeons to consider a large number of individual factors when making decisions with patients about their treatment-this is what we mean by "precision surgery".Abstract The incidence of colorectal cancer and colorectal liver metastases (CRLM) is increasing globally due to an interaction of environmental and genetic factors. A minority of patients with CRLM have surgically resectable disease, but for those who have resection as part of multimodal therapy for their disease, long-term survival has been shown. Precision surgery-the idea of careful patient selection and targeting of surgical intervention, such that treatments shown to be proven to benefit on a population level are the optimal treatment for each individual patient-is the new paradigm of care. Key to this is the understanding of tumour molecular biology and clinically relevant mutations, such as KRAS, BRAF, and microsatellite instability (MSI), which can predict poorer overall outcomes and a poorer response to systemic therapy. The emergence of immunotherapy and hepatic artery infusion (HAI) pumps show potential to convert previously unresectable disease to resectable disease, in addition to established systemic and locoregional therapies, but the surgeon must be wary of poor-quality livers and the spectre of post-hepatectomy liver failure (PHLF). Volume modulation, a cornerstone of hepatic surgery for a generation, has been given a shot in the arm with the advent of liver venous depletion (LVD) ensuring significantly more hypertrophy of the future liver remnant (FLR). The optimal timing of liver resection for those patients with synchronous disease is yet to be truly established, but evidence would suggest that those patients requiring complex colorectal surgery and major liver resection are best served with a staged approach. In the operating room, parenchyma-preserving minimally invasive surgery (MIS) can dramatically reduce the surgical insult to the patient and lead to better perioperative outcomes, with quicker return to function.