OBJECTIVES: To assess the value of additional research for testing carcinoembroynic antigen (CEA), cancer antigen (CA)15-3 and CA 27.29 biomarkers for earlier detection and treatment of recurrent breast cancer. METHODS: We developed a decision-analytic model to estimate the expected value of perfect information (EVPI) and expected value of sample information (EVSI) for a treatment strategy involving biomarker testing every 3-6 months for the five years following completion of primary therapy (in addition to standard care), versus standard care alone.  Model parameters and uncertainty ranges were derived from published literature and expert opinion. EVPI and EVSI were assessed at various willingness-to-pay thresholds.  The affected population was estimated from published recurrence data over a discounted 10-year time horizon. RESULTS: At a willingness-to-pay of $150,000 per quality-adjusted life year, the biomarker strategy and standard-care strategy resulted in average net-benefits of $598,000 and $600,000, respectively. The standard care strategy produced greater net-benefit in 57% of simulations. Among the 43% of simulations where standard care produced greater net-benefit, the average difference was $11,200. With an affected population of approximately 417,000 patients, the EVPI was $2.1 billion. Preliminary EVSI estimates range from $36 to $76 million at sample sizes between 500 to 5,000 patients per arm, respectively. CONCLUSIONS: Our findings indicate that research assessing the use of breast cancer recurrence biomarkers and consequent earlier treatment could be highly valuable. The EVPI of approximately $2.1 billion represents the upper bound of the value of additional research, and is driven by the affected population, testing sensitivity and specificity, costs, and uncertainty in the choice of optimal strategy. We are currently conducting EVSI analyses for various trial designs, compared to the cost of conducting these trials. Our analysis allows decision makers to quantitatively assess and prioritize research efforts in biomarker testing for breast cancer recurrence relative to alternative research investments.