Progression-Free Survival

Progression-Free Survival (PFS) is the length of time during and after treatment that a patient lives with the disease without it getting worse on imaging or clinical exams. It is measured from a defined starting point, usually the first day of treatment or enrollment in a clinical trial, until the cancer grows, spreads, or the patient dies from any cause. PFS is a common way researchers measure whether a treatment is working before overall survival data are mature.

Origin

The term emerged in oncology clinical trials in the 1980s–1990s as researchers sought earlier endpoints than overall survival to evaluate new cancer drugs. It was formalized through regulatory guidance from the U.S. Food and Drug Administration and the European Medicines Agency, and is now standardized in mesothelioma trials using response criteria such as modified RECIST.

Significance in Asbestos Context

For mesothelioma patients, PFS is one of the main numbers reported in studies of chemotherapy, immunotherapy (such as nivolumab plus ipilimumab), and surgical multimodal therapy, so it directly affects which treatments are offered and in what order. In a legal case, PFS data from a patient's medical record (scans showing stable disease versus progression) helps establish the clinical course, the burden of treatment, and the time during which the patient could function, all of which feed into damages for pain, suffering, and lost quality of life. Defendants sometimes argue that a longer PFS suggests less severe disease, while plaintiffs use the same data to document the continuous medical surveillance and anxiety of living with an incurable cancer. Because PFS is a surrogate endpoint, it is not the same as cure or long-term survival, and experts may disagree about how much weight to give it.

Example Sentence

The oncologist explained that the immunotherapy combination had shown a median progression-free survival of about seven months in pleural mesothelioma trials, which helped the family understand what to expect from the next scan.

Related Terms

Overall Survival, Modified RECIST, Mesothelioma, Surrogate Endpoint, Clinical Trial, Disease Progression

Notes

• Ask your oncologist what scanning schedule will be used to measure progression (typically CT every 6–9 weeks) and request copies of every radiology report. These become key evidence of disease course in a claim.
• Keep a personal log of symptoms, treatments, and side effects alongside the scan dates; PFS numbers from trials are averages and your individual timeline matters more for both medical decisions and damages.
• If you are considering a clinical trial, ask whether the trial's primary endpoint is PFS or overall survival, and what the difference means for you. A drug that improves PFS doesn't always extend life.
• Preserve all imaging reports, tumor measurements, and oncology notes describing 'stable disease,' 'partial response,' or 'progression,' as these specific terms carry defined meanings that your legal team's medical expert will rely on.