Defined criteria for resectability improves rates of secondary resection after systemic therapy for liver limited metastatic colorectal cancer

Aims: Long-term survival has been demonstrated for patients with irresectable colorectal liver metastases who are brought to resection by chemotherapy. However, it remains unclear whether improved long-term outcome seen with modern therapies translates to increased rates of secondary resection and whether response rates correlate with rates of secondary liver resection.

Methods: A systematic review of literature published between January 1998 and September 2013 was performed. Phase II/III trials were included if they reported the rate of objective response and the rate of secondary resection of initially irresectable metastases. For the phase III trials, the ratio between response and resection rates within the trials was investigated as well as the correlation for both parameters in all trials.

Results: Twenty-five studies were identified. Response rate demonstrated a strong correlation with rates of secondary resection (R(2)=0.44, p=0.008). Ratios of response/resection between both arms of 10 randomised control trials (RCTs) were calculated to control for selection bias, and showed that in a randomised setting response rates correlate with increased rates of secondary resection in an intra-trial comparison (R(2)=0.87, p=0.002). Linear regression analysis demonstrated a significant difference between studies where criteria for resectability were defined (median 39.5%), and those where it was not (median 11%) (p=0.006).

Conclusion: There is a clear correlation between radiological response and rates of secondary resection, with studies that define resectability achieving much higher rates. All trials investigating first line treatment in patients with metastatic colorectal cancer should have criteria for resection, with conversion to secondary resection as a defined study end-point.