Progression-free survival

What it is

Progression-free survival is the length of time, after treatment, during which a glioma does not grow or worsen (does not "progress"). It measures how long a treatment keeps the tumor controlled and is reported for groups of patients, complementing overall survival.

Understanding Progression-free survival

While overall survival measures living longer, progression-free survival measures how long the tumor stays in check after treatment before it grows or worsens. It is a useful measure of a treatment's ability to control the tumor and is often reported in studies — for example, a treatment that lengthens progression-free survival keeps the tumor stable for longer. For some gliomas, delaying progression is itself a meaningful goal (it can mean a longer period of stability and well-being, and can postpone the need for further treatment). As an example, the IDH inhibitor vorasidenib was shown to substantially extend progression-free survival in certain grade 2 IDH-mutant gliomas. Like other statistics, progression-free survival describes groups and probabilities, not individual certainties, and individual courses vary. It is interpreted alongside overall survival and quality of life. Understanding progression-free survival in gliomas clarifies a measure of how long treatment controls the tumor.

Why it matters

Understanding progression-free survival helps patients and families interpret a measure of tumor control — how long a treatment keeps the tumor stable — which can mean a longer period of well-being, while recognizing it describes groups, not individuals.