Cost-Effectiveness of Surveillance after Metastasectomy of Stage IV Colorectal Cancer

SIMPLE SUMMARY: Up to 65% of patients with metastatic colorectal cancer experience disease recurrence following curative-intent metastasectomy. Certain oncology organizations recommend surveillance to detect recurrent disease at an early phase to allow for the greatest benefit from additional treatment. Surveillance programs may involve colonoscopy, physical examination, carcinoembryonic antigen testing, and computed tomography at regular intervals. Even though surveillance can be highly effective, there is little evidence for its use in metastatic colorectal cancer and no clear consensus on the best strategy. We used decision analysis and a population-based cohort to evaluate the cost-effectiveness of various surveillance strategies following curative-intent metastasectomy in patients with stage IV colorectal cancer. Our results show that surveillance with clinic visits and investigations every 12 months for 5 years would be cost-effective in a Canadian context. These findings demonstrate the utility of economic analysis for guiding the management of stage IV colorectal cancer after metastasectomy. ABSTRACT: Surveillance of stage IV colorectal cancer (CRC) after curative-intent metastasectomy can be effective for detecting asymptomatic recurrence. Guidelines for various forms of surveillance exist but are supported by limited evidence. We aimed to determine the most cost-effective strategy for surveillance following curative-intent metastasectomy of stage IV CRC. We performed a decision analysis to compare four active surveillance strategies involving clinic visits and investigations elicited from National Comprehensive Cancer Network (NCCN) recommendations. Markov model inputs included data from a population-based cohort and literature-derived costs, utilities, and probabilities. The primary outcomes were costs (2021 Canadian dollars) and quality-adjusted life years (QALYs) gained. Over a 10-year base-case time horizon, surveillance with follow-ups every 12 months for 5 years was most economically favourable at a willingness-to-pay threshold of CAD 50,000 per QALY. These patterns were generally robust in the sensitivity analysis. A more intensive surveillance strategy was only favourable with a much higher willingness-to-pay threshold of approximately CAD 425,000 per QALY, with follow-ups every 3 months for 2 years then every 12 months for 3 additional years. Our findings are consistent with NCCN guidelines and justify the need for additional research to determine the impact of surveillance on CRC outcomes.