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

周一，一项调查研究发现，业余时间做锻炼能降低13种癌症发病率，包括肝癌、乳癌。

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

之前数百项调查已经研究过身体锻炼和癌症之间的关系，发现体育锻炼可以降低直肠癌、乳房癌和子宫癌的发病率。然而由于调查对象数量有限，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, who were followed for a median of 11 years.

由美国国家癌症研究所Steven Moore和其同事进行了一项为期11年的调查，调查覆盖美国和欧洲144万人，年龄从19岁到98岁不等。

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

调查参与者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;进行了多少身体锻炼。

During the study peroid, about 187,000 new cases of cancer occurred in the study participants.

在调查过程中，参与者出现了187000种新型的癌症。

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.

调查证实业余锻炼能降低癌症发病率，直肠癌发病率降低16%，乳房癌10%，子宫癌21%。

The researchers also determined 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), gastric 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%)。

Myeloma and cancers of the head and neck, rectum, and bladder also showed reduced risks that were significant, but not as strong.

白血病，头部和颈部、直肠和膀胱部位的癌症风险也会降低，但不是很明显。

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

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.

总起来说，身体锻炼多的人群可降低7%的癌症发病率。

Most of the associations remained regardless of body size, suggesting that exercise acts through mechanisms other than lowering body weight to reduce cancer risk.

很多关联没有考虑身体重量因素，建议通过机械来锻炼身体，而不是单纯靠减肥来降低癌症风险。

"Our results support that these associations are broadly generalizable to different populations, including people who are overweight or obese, or those with a history of smoking," said Moore.

“我们的调查结果适用于广泛的人群，包括肥胖人群和老烟民，” Moore说道。

"Health care professionals counseling inactive adults should promote physical activity as a component of a healthy lifestyle and cancer prevention."

“健康专业老师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。”