Differences in management and outcome for colon and rectal carcinoma with synchronous liver metastases: a population-based cohort study.

AIM Surgical treatment of colorectal cancer with synchronous colorectal liver metastases (SCRLM) offers three different strategies with regards to the timing of liver resection. The aim of the study was to describe the selection of surgical strategy, focusing on differences between colon and rectal cancer with SCRLM, postoperative morbidity/mortality and survival. METHOD A retrospective population-based study of patients with SCRLM registered in Swedish Colorectal Cancer Registry in the region Stockholm/Gotland during 2010-2017 and treated with surgical resection of primary tumour and liver metastases (LM). Patients were followed for five years or censored at November 22, 2018. RESULTS A total of 238 patients met the inclusion criteria during the study period. Patients with rectal cancer were treated with 'liver first' in 70%, whereas the main treatment strategies for colonic tumours were 'simultaneous resection' 44% and 'primary first' 37%. Rectal cancer had superior 5-year survival rate compared to colon tumours with SCRLM, 62 vs. 47% (p = 0.033). There was no difference in survival between treatment strategies irrespective of primary tumour location. Postoperative complications occurred most commonly among rectal tumours treated with simultaneous resection, (p = 0.024). CONCLUSION Patients with rectal cancer and SCRLM were treated with 'liver first' to a higher degree than patients with colon cancer. Patients with rectal cancer and SCRLM where both primary tumour and LM were operated, had significantly better survival than corresponding patients with colon cancer.