Progression-free survival (PFS) is a surrogate endpoint defined as follows (by ChatGPT):
Essentially, PFS is the length of time a patient's disease does not worsen or progress during a clinical study or treatment regimen. For example, in cancer research, it measures the time from the start of treatment until the cancer shows signs of growth, spread, or recurrence.
Understanding PFS is critical because it helps clinicians and researchers evaluate the effectiveness of treatments in controlling the disease. Longer PFS showed that treatment successfully slowed disease progression. This metric is especially important in clinical trials when comparing different treatments or drugs.
A key question is, do patients care about PFS? The answer is probably yes, since better PFS is often (but not always) associated with longer survival. However, do patients value PFS regardless of OS? Perhaps so if they had better quality of life (i.e., fewer symptoms) during the preprogressive phase. Or, they may feel less anxious if they know their cancer is not progressing.
What does the literature say?
A paper by Raphael et al. (2019) A systematic literature review was conducted on studies assessing whether patients with advanced cancer understand and value PFS. Overall, 17 studies met the inclusion criteria. These:
Ten studies specifically presented the term to patients progression-free survival Select as an attribute.Of the words used to define the attribute of PFS, 6 studies used this term Survive. Five studies clarified that PFS may not translate into better overall survival, and another five studies explained that improvements in PFS may not reflect how patients feel. No studies have clarified that PFS events may represent progression or death, and no studies have defined for patients what constitutes progression. The studies reviewed in this article underrepresented ethnic and racial minorities (mean percentage of white patients, 88%; range, 77%-96%). Although only a few studies have evaluated this, given the different relative preferences assigned to cost and efficacy outcomes in North American versus Asian studies, values and preferences may differ across cultural contexts.
As can be seen from the table below, there is significant heterogeneity in the way PFS is presented to cancer patient respondents.
In some studies, PFS is the most important attribute. In other cases, quality of life factors are more important. But overall, it is clear that more research is needed to fully understand how patients perceive the value of PFS.
