A quantitative analysis of published randomized clinical trials challenges the idea that progression-free survival (PFS) should be the sole primary endpoint in cancer trials. Researchers at McMaster University in Ontario, Canada looked at 38 randomized clinical trials involving 13,979 patients with 12 different types of cancer. After gathering data from studies of clinical trials published from January 1, 2000 through May 4, 2016, they concluded that there is no significant association between survival when the disease is not becoming worse (or PFS) and health-related quality of life (HRQoL).
According to Feng Xie, study co-author and professor of health research methods and evidence at McMaster University, there are only two reasons to use PFS as a valid marker for cancer survival: 1) it is a viable indicator for overall survival and 2) it assumes that patients who live longer without cancer progression will have a better quality of life, even without extended survival.
A rigorous and trustworthy measurement of HRQoL in future studies would be worthwhile due to the cost of new oncological therapies, according to Xie and his co-authors, whose study was recently published in JAMA Internal Medicine. This would ensure that patients receive the best possible benefit from cancer therapies.
“Access to these types of drugs is costing our health care system a lot of money, and … we do not have strong enough evidence to show that some of [them] can extend a patient’s life or improve … quality of life,” Xie said.
The problem, according to Diana Zuckerman, head of the National Center for Health Research, is that the FDA lets companies use outcome measures, which do not necessarily determine health but supposedly predict health outcomes.
While endpoints might be valid and everyone agree they should predict a better outcome, this is not always the case. For instance, the fact that a particular drug might work well at controlling a diabetic’s glucose levels does not translate to the patient living longer or having a better quality of life.