Progression-Free Survival (PFS) is a clinical trial endpoint that measures the length of time during and after treatment that a patient lives with a disease (typically cancer) without it worsening.

PFS is defined as the time from the start of treatment (or randomization) until:

• Objective disease progression, as determined by standardized criteria (e.g., RECIST), or
• Death from any cause, whichever occurs first.

• Indicates the period of disease control under a given therapy.
• Does not require death to be observed.
• Commonly used in oncology trials as a surrogate endpoint for overall survival (OS), especially when OS is difficult to measure in a timely manner.
• Higher PFS values may suggest greater efficacy of the therapeutic intervention.

• May not always correlate with overall survival.
• Interpretation can be affected by assessment intervals and imaging frequency.
• Subject to investigator bias if not blinded.

• Overall Survival (OS)
• Response Evaluation Criteria in Solid Tumors (RECIST)
• Disease-Free Survival (DFS)