A pooled analysis of
nine prospective studies involving more than 750,000 adults finds that
recommended amounts of leisure-time physical activity were linked to a lower
risk for seven cancers, with several cancer types having a ‘dose/response’
relationship. The study was led by investigators at the National Cancer
Institute, the American Cancer Society, and the Harvard T.H. Chan School of
Public Health and appears in the Journal of Clinical Oncology.
While
it’s long been known that physical activity is associated with a lower risk of
several cancers, less clear has been the shape of the relationship and whether
recommended amounts of physical activity are associated with lower risk.
Updated guidelines for activity now state that people should aim for 2.5 to 5
hours/week of moderate-intensity activity or 1.25 to 2.5 hours/week of vigorous
activity. Moderate-intensity activities are those that get you moving fast
enough or strenuously enough to burn off three to six times as much energy per
minute as sitting quietly (3 to 6 METs). Vigorous-intensity activities burn
more than 6 METs.
For
the current analysis, investigators pooled data from nine prospective cohorts
with self-reported leisure-time physical activity and follow-up for cancer
incidence, looking at the relationship between physical activity with incidence
of 15 types of cancer.
They
found engaging in recommended amounts of activity (7.5 to 15 MET hours/week)
was associated with a statistically significant lower risk of seven of the 15
cancer types studied, with the reduction increasing with more MET hours.
Physical activity was associated with a lower risk of colon cancer in men (8%
for 7.5 MET hours/week; 14% for 15 MET hours/week), female breast cancer
(6%-10%), endometrial cancer (10%-18%), kidney cancer (11%-17%), myeloma
(14%-19%), liver cancer (18%-27%), and non-Hodgkin lymphoma (11%-18% in women).
The dose response was linear in shape for half of the associations and
nonlinear for the others.
The
analysis had some limitations: Even with 750,000 participants, patient numbers
were limited for some cancers; participants were primarily white; there was a
limited number of cohorts with detailed physical activity measures; and the
authors relied on self-reported physical activity.
The
authors conclude: “These findings provide direct quantitative support for the
levels of activity recommended for cancer prevention and provide actionable
evidence for ongoing and future cancer prevention efforts.”
“Physical
activity guidelines have largely been based on their impact on chronic diseases
like cardiovascular disease and diabetes,” said Alpa Patel, Ph.D., senior
scientific director of epidemiology research at the American Cancer Society.
“These data provide strong support that these recommended levels are important
to cancer prevention, as well.”
No comments:
Post a Comment