Progression-free survival


Progression-free survival is "the length of time during and after the treatment of a disease, such as cancer, that a patient lives with the disease but it does not get worse". In oncology, PFS usually refers to situations in which a tumor is present, as demonstrated by laboratory testing, radiologic testing, or clinically. Similarly, "disease-free survival" is when patients have had operations and are left with no detectable disease.
Time to progression does not count patients who die from other causes but is otherwise a close equivalent to PFS. The FDA gives separate definitions and prefers PFS.

Background

PFS is widely used in oncology. The definition of "progression" generally involves imaging techniques or other aspects: biochemical progression may be defined on the basis of an increase in a tumor marker.
change in the radiological aspect of a lesion is defined according to RECIST criteria. Progression may also be due to the appearance of a new lesion or to unequivocal progression in other lesions.
Progression-free survival is used as an alternative to overall survival, only be available after a longer time than PFS. In some cancers PFS and OS are strictly related, but in others they are not. In a time trade off study in renal cancer, physicians rated PFS the most important aspect of treatment, while for patients it fell below fatigue, hand foot syndrome, and other toxicities. et al.>

Special aspects

By definition PFS refers to the date on which progression is detected. An advantage of measuring PFS over measuring OS is that PFS appears sooner than deaths, allowing faster trials.
The use of PFS for proof of effectiveness and regulatory approval is controversial. It is often used as a clinical endpoint in randomized controlled trials for cancer therapies. It is a metric frequently used by the UK National Institute for Health and Clinical Excellence and the U.S. Food and Drug Administration to evaluate the effectiveness of a cancer treatment.
PFS improvements do not always result in corresponding improvements in overall survival, and the control of the disease may come at the biological expense of side effects from the treatment itself. This has been described as an example of the McNamara fallacy.