The criteria categorize tumor responses into four main categories: Complete Response (CR), Partial Response (PR), Stable Disease (SD), and Progressive Disease (PD). A complete response indicates the disappearance of all target lesions, whereas a partial response signifies at least a 30% decrease in the sum of the diameters of target lesions. Stable disease reflects no significant change, while progressive disease denotes a 20% increase in the sum of diameters or the appearance of new lesions.