人们早已知道，体育锻炼与患多种癌症的风险降低有关，但这种关系的形式以及体育锻炼的建议摄入量是否与较低的风险有关尚不清楚。现在，最新的活动指南指出，人们应该将目标定为每周进行2.5至5小时的中等强度运动或每周进行1.25至2.5小时的剧烈运动。中等强度的活动可以使您足够快或足够剧烈地运动，使每分钟消耗的能量消耗比安静地坐下来（3到6 MET）多三到六倍。剧烈运动可燃烧6 MET以上。
他们发现参与建议的活动量（7.5至15 MET小时/周）与所研究的15种癌症中的7种在统计学上显着较低的风险相关，随着MET小时的增加，减少的风险增加。身体活动与男性患结肠癌的风险较低相关（7.5 MET /周每周8％; 15 MET /周每周14％），女性乳腺癌（6％-10％），子宫内膜癌（10％- 18％），肾癌（11％-17％），骨髓瘤（14％-19％），肝癌（18％-27％）和非霍奇金淋巴瘤（女性为11％-18％）。对于一半的关联，剂量响应的形状是线性的，对于其他关联，则是非线性的。
“体育活动指南主要是基于其对诸如心血管疾病和糖尿病等慢性疾病的影响，”美国癌症协会流行病学研究高级科学总监Alpa Patel博士说。 “这些数据提供了有力的支持，这些建议的水平对预防癌症也很重要。”
Report links recommended physical activity levels to lower risk of seven cancers
More activity linked to lower risk for several cancer types
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.”
Article: Amount and Intensity of Leisure-Time Physical Activity and Lower Cancer Risk, Matthews et al. J Clin Oncol 2019; doi 10.1200/JCO.19.02407