ALK and neoplasm: Progression-free survival is not affected by such treatment switches; however, it may be prone to measurement error and bias, and it does not capture the entire treatment effect on outcomes that are important to participants (e.g., prolonged survival, quality of life).[53] Along with a longer duration of progression-free survival, improved quality of life was noted in several RCTs with the use of ALK inhibitors, suggesting that extending the period before tumour progression will be of value to patients.