Neoadjuvant chemotherapy for resectable colorectal liver metastases: what is the evidence? Results of a systematic review of comparative studies.

Background: The role of preoperative chemotherapy for resectable colorectal liver metastases is still highly controversial. The purpose of this systematic review is to summarize the current evidence on this topic.

Methods: A systematic literature search was performed to identify all studies published from January 2003 up to and including January 2014 regarding patients with initially resectable colorectal liver metastases. Data were examined for information about indications, operation, neoadjuvant and adjuvant therapies, perioperative results, and survival.

Results: Fourteen retrospective studies published between 2003 and 2014 satisfied the inclusion criteria, including 1607 patients who underwent pre-operative chemotherapy and liver resection (NEO-CHT group), and 1785 patients submitted to hepatectomy with or without post-operative chemotherapy (SURG group). Postoperative mortality rates ranged from 0 to 5% in the NEO-CHT group and from 0 to 4% in SURG group. Complications ranged from 7 to 63% in both groups. Adopted pre-operative chemotherapy protocols were highly heterogeneous. The 5-year overall survival rates ranged from 38.9 to 74% in the NEO-CHT group and from 20.7 to 56% in the SURG group, with no significant difference in seven of eight studies.

Discussion: This review shows that there is a lack of clear evidence on the role of neoadjuvant chemotherapy in the treatment of resectable colorectal metastases in the literature. The majority of studies were retrospective and there was high heterogeneity among them in the treatment protocols. The EORTC 40983 trial and the majority of retrospective studies did not find any overall survival advantage in patients treated with neoadjuvant therapy. Additional high-quality studies (randomized) are needed to shed light on this topic.