Adults who have undergone successful
cancer treatment years or decades ago become fatigued more quickly than their
peers who don’t have cancer histories, according to a new study in the
journal Cancer from scientists at Johns Hopkins Bloomberg
School of Public Health (JHSPH).
The scientists examined data from a
long-running study of normal aging, which included periodic treadmill tests of
fatigability as well as 400-meter walks to test endurance. They found that, on
average, participants with a history of cancer treatment reported more fatigue
in the treadmill tests and were slower to complete the endurance walks,
compared to participants without a cancer history.
“The main goal of cancer treatment
has been survival, but studies like this suggest that we need also to examine
the longer-term effects on health and quality of life,” said study senior author
Jennifer A. Schrack, PhD, assistant professor in JHSPH’s Department of
Epidemiology.
Looming concerns over the long-term
adverse effects of cancer treatments are largely the result of the short-term
successes of those treatments, which have left a growing population of cancer
survivors: 16 million in the United States as of 2016. But studies suggest that
cancer treatments’ lingering impacts are clinically real and often resemble an
accelerated aging process, including cognitive impairments, heart disease,
secondary cancers, and—most commonly—fatigue.
Fatigue as a general feeling is
difficult to measure in an objective way, but Schrack and her colleagues,
including lead author Gillian Gresham, a doctoral candidate at the time of the
study, examined it in the specific context of physical exertion.
Their dataset came from the
Baltimore Longitudinal Study of Aging (BLSA), a project that has enrolled
thousands of people in the Baltimore/Washington area since 1958 and generally
follows them for life with periodic health checks. Since 2007, these checks
have included measures of endurance and “fatigability” during walks and
treadmill tests.
“Researchers at the National Cancer
Institute suggested that we look at these BLSA data to see if there were
differences in otherwise healthy older adult cancer survivors,” Schrack said.
“We were surprised by the magnitude of the differences we found.”
The fatigability test for BLSA participants
involved a treadmill walk, after which they were asked to rate their perceived
exertion.
After adjusting for gender- and
health-related differences between 334 participants who had a history of cancer
and 1,331 who didn’t, the researchers found that a cancer history was
associated with a 1.6 times greater risk of high perceived fatigability. The
mean ages were 74 years for the 334 people in the cancer history group and 69
years for the 1,331 in the no-cancer history group. By comparison, the team
found that being older than 65 years brought a 5.7 times greater risk of high
perceived fatigability—implying that the effect of a cancer history was more than
a third as large as the effect of aging past 65.
Similarly, a cancer history was
associated with 400-meter walk times averaging 14 seconds slower than those for
participants with no cancer history—which again was a bit more than a third of
the slowing effect (36 seconds) that came from aging past 65. The over-65
participants with a cancer history also deteriorated more steeply in their
endurance-walk times from one checkup to the next, compared to those without a
cancer history.
“These findings support the idea
that a history of cancer is associated with higher fatigability and that this
effect worsens with advancing age,” Schrack said.
She and her colleagues aim to follow
up with studies of larger groups of cancer survivors for whom there are more
data on cancer type, treatment type, and other important factors. Such studies
could distinguish the long-term adverse effects of different cancer treatment regimens
and could even help reveal the biological mechanisms underlying those adverse
effects.
“The long-term goal is that doctors
and patients will be able to take those specific long-term effects into account
when they decide how to treat different cancers,” Schrack said.
This article was adapted
from information provided by JHSPH.