The treatment of cancer has evolved from non-specific chemotherapy to immune checkpoint inhibitors. The costs of newer treatments are high and access is challenging for payers as there are many uncertainties relating to efficacy, safety and benefits to patients’ quality of life. Health technology assessment incorporating health economic modelling is pivotal for managing the financial risks of oncology treatments, but better methods are needed to ensure timely access to appropriate new oncology therapies. This work highlights the key issues pertaining to health economic modelling and offers potential solutions.