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 It was an observational study and can’t prove cause and effect, but
cancer survivors who watched more than five hours of TV per day were
more likely to die than those who watched less than two hours, said
lead author Hannah Arem of the National Cancer Institute in
Bethesda, Maryland.
“Our findings suggest that for the one million colorectal cancer
survivors in the US, both minimizing TV viewing (fewer than two
hours per day) and increasing exercise (4-plus hours per week) may
be associated with improved survival,” Arem told Reuters Health by
email.
In a 1995-1997 National Institutes of Health study, more than
560,000 people, ages 50 to 71, had filled out health questionnaires.
Using state cancer registries, Arem and colleagues found that by
2006, almost 4,700 of the original participants had received new
diagnoses of invasive colorectal cancer.
Nearly 3,800 of those patients were still alive, and without
metastatic cancer, when researchers mailed out new questionnaires in
2005.
At both points - 1995 and 2005 - participants estimated the hours
per week they spent in leisure activities like tennis, golf, biking,
swimming, heavy gardening, fast walking, dancing, or aerobics.
They also reported how many hours they spent watching TV or videos.
Those who spent more than seven hours per week in physical
activities were 20 percent less likely to die of any cause during
the study than less active people.
After a colon cancer diagnosis, those who exercised at least seven
hours per week were 31 percent less likely to die from any cause
than those who did not exercise at all, according to results in the
Journal of Clinical Oncology.
Physical activity levels didn’t seem to be linked to colon cancer
death specifically.
For TV time, those who reported more than five hours per day before
diagnosis were 22 percent more likely to die during the study than
those who reported less than two hours per day.
“This study provides some new evidence that watching TV after a
diagnosis of colorectal cancer may decrease overall survival as well
as survival associated with colon cancer diagnosis,” said Christine
Friedenreich, of the department of Cancer Epidemiology and
Prevention Research of CancerControl Alberta in Calgary, who was not
part of the new study.
Risk of death did not seem to increase as increments of TV time
increased, she noted.
TV time had not been studied in colorectal cancer survivors, but
these results are similar to studies of TV and mortality in the
general population, Arem said.
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People who reported more weekly leisure activity before cancer
diagnosis tended to have a lower body mass index, better reported
health, less frequent smoking and less TV viewing.
For activity and TV watching, the period after cancer diagnosis
explained the link with mortality, meaning that is an especially
important time to minimize TV and increase physical activity, the
authors write.
“There is already some evidence, albeit still preliminary and
emerging, that higher levels of sedentary behavior increases
mortality associated with other cancers,” Friedenreich told Reuters
Health by email.
Of diseases affecting men and women, colorectal cancer is the second
most common cancer killer in the U.S., killing 51,783 Americans in
2011, according to the Centers for Disease Control and Prevention.
‘Bowel cancer’ is the third most common cancer worldwide and second
most common in Europe, with highest rates in Slovakia and Norway,
according to Cancer Research U.K.
“More research is needed to understand the relationships between
physical activity and TV watching with mortality (especially
mortality due to a specific cancer) among different cancer survivor
groups,” Arem said. “Even within a given cancer site there may be
differences in mortality associations by tumor type.”
A 2009 panel of the American College of Sports Medicine recommended
at least 150 minutes per week of moderate intensity activity for
colorectal cancer survivors, similar to recommendations for the
general U.S. population, she noted.
“The existing evidence of benefit with increasing physical activity
and decreasing sedentary time (which is supported in our study)
suggests that doctors should consider referring colorectal cancer
survivors to lifestyle programs targeted to their specific health
needs,” she said.
SOURCE: http://bit.ly/1Ga5DQl Journal of Clinical Oncology, online
December 8, 2014.
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