Abstract: An example method for quantitatively predicting a cancer patient's response to immune-based or targeted therapy and methods of treatment are described herein. In one aspect, disclosed herein are methods for assaying a cancer patient's response to immune-based or targeted therapy, comprising: measuring tumor burden, such as, measuring total metabolic tumor volume either manually or automatically, prior to administration of the immune-based or targeted therapy to create a baseline tumor burden; wherein a high baseline tumor burden indicates that the patient will have a decreased, less efficacious, and/or less durable response, response to immune-based or targeted therapy.