A systematic analysis highlighting deficiencies in reported outcomes for patients with stage IV colorectal cancer undergoing palliative resection of the primary tumour

Background
Management of the primary tumour in the presence of unresectable metastatic colorectal cancer (mCRC) is controversial. The role of primary tumour resection (PTR) has been investigated by a number of retrospective cohort studies, with a number on going randomised controlled trials. The aim of this study was to identify the clinical and patient-reported outcomes currently reported in studies that evaluate the role of PTR in mCRC.

Methods
Literature searches were performed in MEDLINE (via OvidSP) (1966–June 2017), EMBASE (via OvidSP) and the Cochrane Library using terms related to colorectal cancer and primary tumour resection. All studies documenting outcomes following palliative PTR were included. Eligible articles were assessed using the Risk of Bias In Non-Randomised Studies of Intervention (ROBINS-I) tool.

Results
Of 11,209 studies screened, 59 non-randomised studies reporting outcomes on 331,157 patients were included. Patient characteristics regarding performance status and co-morbidity were recorded in 26 (44.1%) and 17 (28.8%) studies. The chemotherapy regime used was reported in 27 (45.8%) studies. The operative setting and the operative approach was reported in 42 (71%) and 14 (23.7%) studies. Post-operative mortality and morbidity were reported in 33 (55.9%) and 35 (59.3%) studies. Overall survival was reported in 49 (83.1%) studies, with 5 different definitions identified. Quality of life was only reported in 1 (1.7%) study.

Conclusion
This study demonstrates significant heterogeneity in the selection and definition of outcomes reported following PTR in mCRC. There is significant heterogeneity with a significant under-reporting of important outcomes such as treatment related adverse events and patient reported outcomes.