Prognostic factors of hepatectomy in initially unresectable colorectal liver metastasis: Indication for conversion therapy.

The aim of the present study was to retrospectively identify prognostic factors for long-term cumulative survival following liver resection in patients with primarily unresectable colorectal cancer who had previously received conversion therapy. A multicentre study was designed to ascertain the appropriate indication for conversion therapy. The study included 34 patients who underwent conversion therapy at 5 university hospitals. Patients' background, operative factors, recurrence rate and survival rate were evaluated, and factors influencing therapy outcomes were identified. The median duration of preoperative chemotherapy was 3 months and the response rate was 39.8%. Upon resection, the median tumour size was 47 mm and the median number of tumours was 4. The recurrence-free and cumulative survival rates 5 years after liver resection were 13.7 and 39.3%, respectively. Postoperative complications developed in 12 patients. A response rate >40% was indicated with regards to the assessed prognostic factors for long-term cumulative survival following liver resection and an absence of postoperative complications was noted. It was revealed that conversion therapy should be considered prior to liver resection, particularly for patients with response rates exceeding 40%. Absence of postoperative complications is also an independent predictor of long-term cumulative survival after liver resection. In light of these findings, it was consisted that an optimal response rate >40% could be used as an indicator for surgical resection in conversion therapy. In addition, meticulous intra- and postoperative managements are important for decreasing postoperative complications and improving long-term cumulative survival.