Systematic reviews of resection of metastases in metastatic colorectal cancer

Study objectives: Three systematic literature reviews in metastatic colorectal cancer (mCRC) were performed, one to assess initial resectability rates, one to assess resection rates after conversion therapy for initially unresectable metastases, and one to assess survival following post-conversion therapy resection. Conversion therapy consists of mainly systemic therapies that are used to shrink tumours sufficiently to allow resection in previously unresectable disease.Materials and methods: Relevant articles were identified through three separate electronic searches of MEDLINE, MEDLINE In-Process, the Excerpta Medica Database (EMBASE) and the Cochrane Library, and through manual searches of the reference lists of identified articles. The MEDLINE and EMBASE searches were limited to articles published in English, whereas the Cochrane Library search had no language restrictions.Results: Sixteen studies examined initial resectability, and reported definitions of resectability and resection rates. Resection rates varied greatly, ranging from 4–55%. Seventy-four clinical studies investigated resection after conversion therapy for initially unresectable metastases (liver, lung or mixed). Again, they reported a wide variation in resection rates, with overall resection rates ranging from 1–75% and complete resection rates (R0) from 0–39%. From the 29 studies reporting post-conversion therapy resection survival data, overall median survival ranged from 20–63 months and median progression-free survival from 13 to 20 months.Conclusion: The findings from these systematic literature reviews suggest that mCRC resection data from different studies should be interpreted and compared with caution due to differences between studies in definitions of resectability, study designs, patient populations, the year when studies were conducted, and the country/centre where patients were treated.There is a need for more data on conversion therapy, particularly using monoclonal antibodies, and for long-term survival postconversion therapy resection. Pharmacy practice is encouraged to initiate or participate in retrospective or prospective research which examines conversion therapy in their institution.