Cancer and chronic kidney disease prevalence both increase with age. As a consequence, physicians are more frequently encountering older people with cancer who need dialysis, or patients on dialysis diagnosed with cancer. Decisions in this context are particularly complex and multifaceted. In this Review, we aim to provide an overview of the key points to address when making a treatment strategy in these patients. We provide information on what happens if dialysis is not started or is stopped, and how physicians should deal with such patients. Informed decisions about dialysis require a personalised care plan that considers the prognosis and treatment options for each condition while also respecting patient preferences. The concept of prognosis should include quality-of-life considerations, functional status, and burden of care. Close collaboration between oncologists, nephrologists, and geriatricians is crucial to making optimal treatment decisions, and several tools are available for estimating cancer prognosis, prognosis of renal disease, and general age-related prognosis. Emerging evidence shows that these geriatric assessment tools, which measure degrees of frailty, are useful in patients with chronic kidney disease. In this Review, we try to hand tools to practising physicians, to guide decision making regarding the initiation and termination of dialysis in patients with advanced cancer. SML is supported by the US National Cancer Institute Cancer Center Support Grant (award number: P30CA008748). BS and HW are senior clinical investigators of the Research Foundation Flanders (BS: FWO 1842919N. HW: FWO G067014N).
