The impact of surgical resection of the primary tumor on the development of synchronous colorectal liver metastasis: a systematic review

Background: In recent years different therapeutic strategies for synchronously liver metastasized colorectal cancer were described. Apart from the classical staged surgical approach, simultaneous and liver-first strategies are now commonly used. One theoretical drawback of the classical approach is, however, the stimulatory effect on liver metastases growth that may result from resection of the primary tumour. This systematic review, therefore, aims to investigate the current insights on the stimulatory effects of colorectal surgery on the growth of synchronous colorectal liver metastases in humans. Methods: The systematic review was conducted according to the PRISMA statement. A literature search was performed using PubMed and Embase. Articles investigating the effects of colorectal surgery on synchronous colorectal liver metastases were included. Primary endpoints were metastatic tumor volume, metabolic and proliferative activity and tumour vascularization. Results: Four articles meeting the selection criteria were found involving 200 patients. These studies investigate the effects of resection of the primary tumour on synchronous liver metastases using histological and radiological techniques. These papers support a possible stimulatory effect of resection of the primary tumor. Conclusions: Some limited evidence supports the hypothesis that colorectal surgery might stimulate the growth and development of synchronous colorectal liver metastases.