Ms M is a 58-year old woman with a history of stage II ER1 breast cancer treated with surgery, radiation, and chemotherapy 4 years ago. She remains on endocrine therapy. At her follow-up clinic visit, she asks her oncologist Dr R about an advertisement she saw for circulating tumor DNA (ctDNA) testing. She read that the test could show if her cancer is still there or at risk of coming back. The test is commercially available, but Dr R has not used it routinely because of unclear evidence of its impact on outcomes. Dr R reviews the recent literature but is unable to find definitive information on what a positive test means for the likelihood or timing of recurrence. They note that the company's website does not give clear recommendations for further testing or treatment in the event of a positive result. They wonder how to respond to Ms M's request. How should they advise her about the possible results and uncertainties? If Dr R decides to order the test for Ms M, should they offer it to other patients who did not specifically request it? How will Dr R's response impact Ms M's care moving forward?