Progression-free survival — stability without growth

Progression-free survival is an objective clinical trial endpoint defined as the duration from treatment initiation (or study randomisation) until documented tumour progression or death from any cause. Unlike overall survival, PFS focuses directly on tumour stability and growth inhibition.

In oncology research, PFS serves as an essential regulatory endpoint for evaluating targeted agents and chemotherapies. Because it can be measured earlier than overall survival and is unconfounded by subsequent lines of salvage therapy, PFS provides clear evidence regarding a drug's direct ability to arrest disease progression.

PFS is meaningful because periods without tumour growth typically correlate with symptom stability, preserved organ function, and sustained quality of life. For many patients, maintaining a stable tumour means fewer disease-related complications, such as pain, fatigue, or breathing difficulties.

Furthermore, understanding PFS data from published clinical trials helps you and your physician weigh the anticipated benefits of a proposed treatment against its known toxicities, supporting realistic and balanced decisions regarding whether to start or maintain a specific therapy regimen.

PFS is assessed through periodic surveillance scans (CT, MRI, or PET) evaluated using criteria like RECIST. It does not measure a distinct biological biomarker itself, but rather tracks measurable tumour dimensions and clinical signs over scheduled assessment intervals.

PFS is widely utilised as a primary or secondary endpoint across advanced solid tumours, including metastatic breast, colorectal, ovarian, and lung cancers. It is also a fundamental measure in evaluating therapies for haematological conditions such as indolent non-Hodgkin lymphoma and multiple myeloma.

A regimen demonstrating superior PFS in trials is often approved as standard care. In clinical practice, as long as a patient remains within their personal progression-free window without severe toxicity, their current regimen is typically continued to sustain disease control.