Chronic diseases have major impact on cancer risk
medwireNews: Around a fifth of incident cancer cases and over a third of cancer deaths can be attributed to a combination of several chronic diseases and markers, indicates research published in The BMJ.
These proportions are “comparable to the combined contribution of five lifestyle risk factors,” say Xifeng Wu, from The University of Texas MD Anderson Cancer Center in Houston, USA, and collaborators who consider chronic disease “an overlooked” cancer risk factor.
Noting that current global cancer prevention strategies generally focus on lifestyle factors, they caution that “a major player will be missed” if future approaches do not target non-cancer chronic conditions.
The study included data on 405,878 individuals who participated in a standardized medical screening program in Taiwan between 1996 and 2007, which involved testing for diabetes, pulmonary disease, and markers of cardiovascular disease (blood pressure, total cholesterol, and heart rate), chronic kidney disease (proteinuria and glomerular filtration rate), and gouty arthritis (uric acid).
After adjusting for confounders, all the diseases and markers – except blood pressure and pulmonary disease – were significantly linked to an elevated risk for incident cancer. And without exception, all were significantly associated with an increased risk for cancer death.
In general the relationships were direct, with the risk rising with increasing severity of the condition or marker. For example, trace proteinuria was associated with a 1.12-fold increased risk for incident cancer, whereas proteinuria raised the risk 1.21-fold. However, total cholesterol had an inverse relationship with the risk for cancer incidence and death, and for some of the markers the associations were U-shaped.
Wu and colleagues developed composite risk scores comprising the eight chronic diseases and markers weighted by the strength of the individual associations, and found a positive dose–response relationship between the scores and cancer risk, such that the highest versus lowest scores were associated with an over twofold and fourfold elevated risk for cancer incidence and mortality, respectively.
They also calculated population attributable fractions, finding that the eight factors together were responsible for 20.5% of cancer incidence and 38.9% of cancer mortality, which were similar to the corresponding proportions of 24.8% and 39.7% attributable to five major lifestyle factors, namely, ever smoking and alcohol consumption, insufficient physical activity, inadequate fruit and vegetable intake, and non-ideal body mass index.
Of note, the authors report that the chronic disease-associated increased risk for incident cancer and death could be attenuated by physical activity by an average of 48% and 27%, respectively.
But they admit that “since physical activity was self reported and might be associated with other unmeasured health related behaviors, more studies are warranted to explore how exercise might modify chronic disease related cancer risk independent of other factors.”
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