Representation of peritoneal metastases in published clinical trials of metastatic colorectal cancer.

Abstract

725 Background: Peritoneal metastases occur in 6-15% of patients with metastatic colorectal cancer. Non-invasive detection of peritoneal metastases is difficult given limitations in discrimination of cross sectional imaging. We hypothesized that patients with peritoneal metastases are underrepresented in clinical trials. Methods: Randomized controlled trials of systemic chemotherapy for metastatic colorectal cancer between 2003-16 were included after a PubMed search. Articles were restricted to those published in leading oncology journals and with ≥100 patients (total). Protocol designs were hand searched to identify whether clinical trials explicitly included or reported on patients with peritoneal metastases. Results: Of 72 clinical trials identified, 7 (10%) studies specifically reported inclusion of peritoneal disease (Table 1). Of 45,783 patients enrolled in all trials, 670 patients (1.5%) specifically had peritoneal metastases. Response for peritoneal disease was measured using Response Evaluation Criteria in Solid Tumors (RECIST) criteria in 6 (of 7, 86%) and modified World Health Organization (WHO) criteria in 1 but not reported in the final manuscript or supplementary material. Peritoneal specific outcomes were not reported in any study. No studies included metastatic colorectal cancer patients with peritoneal metastases alone. Conclusions: Patients with peritoneal metastases are underrepresented in published clinical trials. Specific efforts to include patients, measure burden of disease and response to therapy and report peritoneal specific outcomes are essential to draw generalizable inferences. [Table: see text]