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Being physically active during leisure time may lower a person’s risk of certain cancers, according to a new study.
A high level of physical activity was associated with a 20% lower risk of myeloid leukemia, a 17% lower risk of myeloma, a 9% lower risk of non-Hodgkin lymphoma, and a 7% lower risk of cancer in general.
On the other hand, a high level of physical activity was also associated with a higher risk of malignant melanoma and prostate cancer.
Steven C. Moore, PhD, of the National Cancer Institute in Bethesda, Maryland, and his colleagues reported these findings in JAMA Internal Medicine.
The researchers pooled data from 12 US and European study cohorts with self-reported physical activity (1987-2004). And they analyzed associations between physical activity and 26 types of cancer.
The study included 1.4 million participants, and 186,932 cancers were identified during a median of 11 years of follow-up.
Compared with the lowest level of leisure-time physical activity (10th percentile), the highest level of activity (90th percentile) had strong inverse associations (a 20% or greater reduction in risk) for 7 cancer types:
- Myeloid leukemia (hazard ratio [HR]=0.80 [95% CI, 0.70-0.92])
- Esophageal adenocarcinoma (HR=0.58 [95% CI, 0.37-0.89])
- Liver cancer (HR=0.73 [95% CI, 0.55-0.98])
- Lung cancer (HR=0.74 [95% CI, 0.71-0.77])
- Kidney cancer (HR=0.77 [95% CI, 0.70-0.85])
- Gastric cardia (HR=0.78 [95% CI, 0.64-0.95])
- Endometrial cancer (HR=0.79 [95% CI, 0.68-0.92]).
There were moderate inverse associations (a 10% to 20% reduction in risk) between the highest level of activity and 6 cancers:
- Myeloma (HR=0.83 [95% CI, 0.72-0.95])
- Colon cancer (HR=0.84 [95% CI, 0.77-0.91])
- Head and neck cancer (HR=0.85 [95% CI, 0.78-0.93])
- Rectal cancer (HR=0.87 [95% CI, 0.80-0.95])
- Bladder cancer (HR=0.87 [95% CI, 0.82-0.92])
- Breast cancer (HR=0.90 [95% CI, 0.87-0.93]).
And there were suggestive inverse associations between the highest level of activity and 3 cancers:
- Non-Hodgkin lymphoma (HR=0.91 [95% CI, 0.83-1.00])
- Gallbladder cancer (HR=0.72 [95% CI, 0.51-1.01])
- Small intestine cancer (HR=0.78 [95% CI, 0.60-1.00]).
However, the highest level of activity was also associated with an increased risk of prostate cancer (HR=1.05 [95% CI, 1.03-1.08]) and malignant melanoma (HR=1.27 [95% CI, 1.16-1.40]).
The researchers said the main limitation of this study is that they cannot fully exclude the possibility that diet, smoking, and other factors may have affected these results. Also, the study used self-reported physical activity, which can mean errors in recall.
Still, the team said these findings support promoting physical activity as a key component of population-wide cancer prevention and control efforts.
