REVIEW Simultaneous versus staged colorectal and hepatic resections for colorectal cancer with synchronous hepatic metastases: a meta-analysis of outcomes and clinical characteristics Shahin Hajibandeh 1 & Shahab Hajibandeh 2 & Abida Sultana 1 & Gabriella Ferris 1 & Josiah Mwendwa 1 & Ali Yasen Y. Mohamedahmed 1 & Shafquat Zaman 1 & Rajeev Peravali 1 Accepted: 6 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Objectives To evaluate the comparative outcomes and clinical characteristics of simultaneous and staged colorectal and hepatic resections for colorectal cancer with synchronous hepatic metastases. Methods We conducted a systematic search of electronic information sources, and bibliographic reference lists. Perioperative morbidity and mortality, anastomotic leak, wound infection, bile leak, bleeding, intra-abdominal abscess, sub-phrenic abscess, reoperation, recurrence, 5-year overall survival, procedure time, and length of hospital stay were the evaluated outcome param- eters. Combined overall effect sizes were calculated using random-effects model. Results We identified 41 comparative studies reporting a total of 12,081 patients who underwent simultaneous (n = 5013) or staged (n = 7068) resections for colorectal cancer with synchronous hepatic metastases. There were significantly lower use of neoadjuvant chemotherapy (p = 0.003), higher right-sided colonic resections (p < 0.00001), and minor hepatic resections (p < 0.00001) in the simultaneous group. The simultaneous resection was associated with significantly lower rate of bleeding (OR 0.60, p = 0.03) and shorter length of hospital stay (MD - 5.40, p < 0.00001) compared to the staged resection. However, no significant difference was found in perioperative morbidity (OR1.04, p = 0.63), mortality (RD 0.00, p = 0.19), anastomotic leak (RD 0.01, p = 0.33), bile leak (OR 0.83, p = 0.50), wound infection (OR 1.17, p = 0.19), intra-abdominal abscess (RD 0.01, p = 0.26), sub-phrenic abscess (OR 1.26, p = 0.48), reoperation (OR 1.32, p = 0.18), recurrence (OR 1.33, p = 0.10), 5-year overall survival (OR 0.88, p = 0.19), or procedure time (MD - 23.64, p = 041) between two groups. Conclusions Despite demonstrating nearly comparable outcomes, the best available evidence (level 2) regarding simultaneous and staged colorectal and hepatic resections for colorectal cancer with synchronous hepatic metastases is associated with major selection bias. It is time to conduct high-quality randomised studies with respect to burden and laterality of disease. We recommend the staged approach for complex cases. Keywords Colorectal cancer . Liver metastasis . Simultaneous resection . Staged resection Introduction Liver metastases secondary to colorectal cancer are the most frequently occurring metastatic lesions [1]. Approximately 15% to 25% of patients with colorectal cancer present with synchronous liver metastases at the time of initial presentation [1, 2]. Moreover, 50% of colorectal cancer patients develop liver metastasis during the course of their disease [3]. It has been estimated that around 20–50% of patients with resectable colorectal cancer have liver metastases present synchronously [2]. A complete resection of hepatic metastasis has been dem- onstrated to improve survival and be associated with 5-year survival of up to 40% [4–6]. Shahin Hajibandeh and Shahab Hajibandeh contributed equally to this work. Shahin Hajibandeh and Shahab Hajibandeh are joined first authorship is proposed. * Shahin Hajibandeh shahin_hajibandeh@yahoo.com 1 Department of General Surgery, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, UK 2 Department of General Surgery, Glan Clwyd Hospital, Rhyl, Denbighshire, UK International Journal of Colorectal Disease https://doi.org/10.1007/s00384-020-03694-9