Exercise during leisure time may reduce the risk of 13 types of cancers, including liver cancer and breast cancer, a major study said last Monday.

上周一的一项调查研究表明，业余时间做锻炼能降低包括肝癌、乳癌在内的13种癌症的发病率。

Hundreds of previous studies have examined associations between physical activity and cancer risk and shown reduced risks for colon¹, breast, and endometrial cancers. However, these results have been inconclusive for most cancer types due to small numbers of participants in the studies.

之前已经有数百项调查研究过身体锻炼和癌症之间的关系，这些研究发现，体育锻炼可以降低直肠癌、乳房癌和子宫癌的发病率。然而由于调查对象的数量有限，所以很多癌症类型并没有被包括在内。

In the new study, Steven Moore of the U.S. National Cancer Institute and colleagues examined data from 1.44 million people, aged 19 to 98, from the United States and Europe.

在这一项新调查当中，美国国家癌症研究所的史蒂芬·摩尔和其同事以美国和欧洲各国的年龄从19岁到98岁不等、共计144万人作为调查样本。

Participants were asked whether they did moderate or vigorous intensity² activities in their free time, like walking, running or swimming, and how much physical activity they got.

调查参与者会被问及在业余时间是否进行中度或高强度锻炼，比如散步、跑步和游泳；还有进行了多少身体锻炼。

The study confirmed that leisure-time physical activity, as assessed by self-reported surveys, was associated with a lower risk of colon (16 percent), breast (10 percent), and endometrial (21 percent) cancers.

这项调查结果表明，业余锻炼能降低癌症发病率，比如直肠癌发病率降低了16%，乳房癌降低了10%，子宫癌降低了21%。

The researchers also determined³ that leisure-time physical activity was associated with a lower risk of 10 additional cancers, with the greatest risk reductions for esophageal adenocarcinoma(42 percent), liver(27 percent), gastric⁴ cardia (22 percent), kidney (23 percent), and myeloid leukemia (20 percent).

研究者还确定了身体锻炼能降低另外其他10种癌症的风险，降低幅度最大的是食管腺癌（42%），其次是肝癌（27%），贲门癌（22%），肾癌（23%），骨髓性白血病（20%）。

Risk was reduced for lung cancer, but only for current and former smokers⁵, and the reasons for this are still being studied.

另外，肺癌的发病率也会降低，但只是限于新老烟民，具体原因还在调查中。

Overall, a higher level of exercise was associated with a 7 percent lower risk of total cancer.

总体来说，身体锻炼多的人群的癌症发病率可降低7%左右。

"Our results support that these associations are broadly generalizable to different populations, including people who are overweight or obese⁶, or those with a history of smoking," said Moore. "Health care professionals counseling inactive adults should promote physical activity as a component⁷ of a healthy lifestyle and cancer prevention."

摩尔说道：“我们的调查结果适用于广泛的不同人群，包括肥胖人群和老烟民。卫生保健专业人员鼓励成年人要通过提高体育锻炼来形成健康的生活方式，预防癌症。”