A simple technique to estimate best- and worst-case survival in patients with metastatic colorectal cancer treated with chemotherapy

Abstract

Background: Patients with incurable cancer usually want specific information about prognosis, and clinicians’ estimates are often inaccurate. Studies in breast and lung cancer have suggested that simple multiples of the median overall survival (OS) can accurately estimate the time at which 90%, 75%, 25% and 10% of patients are alive. Patients and methods: We identified 46 phase III randomised clinical trials of chemotherapy in metastatic colorectal cancer, representing data from 29 011 patients. We extracted data on demographics, treatment and survival from 96 patient cohorts and assessed agreement with the estimated survival time points, calculated as 0.25, 0.5, 2 and 3 times the median OS. Results: Median OS was 16.8 months in the trials. There were 342 assessable time points. For 301 of these, the estimated survival time was within 0.75–1.33 of the actual survival time (88% agreement). The worst agreement (76%) was at the earliest (90%) level of survival. Conclusions: Simple multiples of the median OS give reasonable estimates of the times at which different survival levels are reached in patients with metastatic colorectal cancer. Taken with previous studies, these findings are likely to be valid across a large range of patients. We would encourage clinicians to think of prognosis as a trajectory, and to consider quoting survival ranges instead of point estimates, in discussions with patients.