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 "In countries where patients need to pay co-pays, they can use up
all their savings in order to get access to those expensive new
drugs and in the end, they may not extend their lives or improve
their quality of life," Feng Xie, a professor of health economics at
McMaster University, told Reuters Health.
Xie and colleagues reanalyzed data from nearly 40 randomized trials
involving multiple cancer types. They found that "progression-free
survival," or the length of time doctors could keep the cancer under
control, was not linked with health-related quality of life.
These days, cancer researchers and drug companies often use
progression-free survival as a measure of a new drug's
effectiveness, Xie explained by phone.
"In the past, when a new drug was developed, overall survival" -
that is, how long the patient lived - "was the endpoint to evaluate.
A lot of drugs have now been approved based on the benefit of
progression-free survival," Xie said.
One reason for using progression-free survival as a marker of
effectiveness is that it can be measured sooner than overall
survival, so new drugs can make it through the pipeline quicker, Xie
and colleagues explain in JAMA Internal Medicine.
The problem, Xie said, is that progression-free survival, measured
in the short term, doesn't necessarily predict longer life. And as
the new study shows, it may also fail to predict better quality of
life.
"In cancer patients there are two important things when evaluating a
therapy: whether it extends survival and whether it improves quality
of life (even if it doesn't extend survival)," Xie explained.
Although many studies have measured progression-free survival, most
have not reported on health-related quality of life. Xie and his
colleagues were able to find 38 studies, including a total of 13,979
cancer patients with 12 different cancer types, that did look at
both endpoints.
Data pooled from all 38 studies showed no significant association
between progression-free survival and quality of life.
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The researchers had difficulty comparing data from the studies
because quality of life was not always measured in the same way. Xie
hopes that in the future, researchers will standardize the way they
measure quality of life.
Dr. Robert Ferris, director of the Hillman Cancer Center at the
University of Pittsburgh Medical Center, isn't ready to throw out
progression-free survival as an indicator of a cancer drug's
effectiveness. But the early marker may under- or over-estimate the
worth of a medication, Ferris said in a phone interview.
"Early response doesn't always predict long term survival," said
Ferris, who is not affiliated with the new research. "For example,
immunotherapy drugs are known for their long-term benefits but may
not have early rapid shrinkage of a tumor."
Also, Ferris said, measuring quality of life can be tricky.
"Everybody sees it differently," he explained. "Some might see it as
a reduction in pain. Others might see it as the ability to interact
socially or the ability to swallow or the ability to get out of bed.
Others might see it as a reduction in fatigue."
Still, progression-free survival can be used as an early indicator
that researchers are on the right track with a new drug, Ferris
said. When an experimental drug does a good job of controlling a
tumor, for example, that might give researchers the impetus to
conduct larger-scale trials.
"You have to be judicious in how you use it," Ferris concluded.
SOURCE: http://bit.ly/2QoLsZv JAMA Internal Medicine, online October
1, 2018.
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