PFS (Progression-Free Survival)

**What it means:** PFS is a common clinical trial metric. It measures **how long patients live without their disease getting worse** — specifically, without the cancer growing or spreading. It's measured from the start of treatment until the disease shows any sign of progression. **How to interpret it:** A median PFS of 5.3 months (as reported for AVZO-021 in breast cancer patients) means that half the patients lived 5.3 months or longer without disease progression. It's a standard measure in oncology trials, though it doesn't tell you about symptom improvement, quality of life, or whether the drug extended overall lifespan (which is measured by Overall Survival, or OS).