Feasibility Study of Preoperative Exercise Intervention in the Resection of Colorectal Liver Metastasis.

Prehabilitation in Liver Surgery

Introduction Thirty per cent of patients with colorectal cancer have metastatic disease at time of presentation, and a further 20% will develop liver metastases after the primary colorectal malignancy has been resected. Liver resection offers the prospect of cure for a proportion of these patients and, with the increasing use of effective neo-adjuvant chemotherapy, this proportion is increasing. However, liver surgery is associated with significant morbidity and mortality and this may be higher in patients with comorbidity, poor cardiorespiratory fitness and in those who have received neo-adjuvant chemotherapy.

Cardiopulmonary exercise testing (CPET) is a non-invasive assessment of cardiovascular and pulmonary function, which can be quantified by measures such as anaerobic threshold (AT) and VO2peak. The anaerobic threshold is a measure of sustainable exercise, where the VO2peak is a measure of maximal exercise capacity. The AT has been assessed in different surgical groups and has been shown as a useful predictor of postoperative complications and survival. Early work has demonstrated that short periods of preoperative exercise intervention can improve AT and VO2peak. However, no work has to date been undertaken in patients prior to liver surgery.

Hepatic glucose metabolism provides much of the energy requirements of the postoperative period. Work has demonstrated that exercise training increases hepatic glucose production, and that its inhibition has a marked effect on endurance capability. This may be particularly relevant when surgical resections can involve resection of up to 80% of hepatic tissue. However, a link between hepatic gluconeogenic capacity and fitness as assessed by cardiopulmonary exercise testing has not been established.

A demonstrable link between gluconeogenic capacity and cardiopulmonary fitness and an explanation of its underpinning physiology would help explain some of the systemic effects of drug hepatotoxicity. It would also allow development of strategies to improve gluconeogenic capacity that may reduce complications and improve tolerance of many hepatoxic agents such as chemotherapy.