ASCO2013：男性心肺适能可预测癌症风险

　　根据美国临床肿瘤学会(ASCO)新闻发布会上发布的一项研究结果，心肺适能(CRF)检测结果或可预测癌症风险及生存状况，与预测心脏病风险和生存状况等同；心肺适能处于最高水平的男性与处于最低水平的男性相比，肺癌和直结肠癌的风险分别下降68%和38%。心肺适能未能显著降低前列腺癌风险，但男性前列腺癌、肺癌或直结肠癌患者若在中年时期更健康，则死亡风险显著降低(P＜0.001)。

　　既往研究提示，体力活动较多可预防癌症的发生，与之不同的是，本研究着眼于一个非常特殊的标志物——心肺适能。在本研究中，采用最大运动耐量试验测量该指标。适能正常能预防心血管疾病，在降低生存风险方面也有助益，但适能正常是否能预防偶发性癌症、降低癌症诊断后的死亡率，人们并不清楚。为此，佛蒙特大学(伯灵顿)癌症患者心血管预防项目的主任Susan G. Lakoski医生及合作者们进行了本研究并从中推导出答案。

　　这项研究涉及17,049名男性，平均年龄为50岁，研究者们使用踏板或自行车对其进行运动耐量试验并进行危险因素评估，使用代谢当量(MET)记录这些男性的心血管功能，并将其分入CRF五分位数组内。利用Medicare医保年龄段的医保索赔数据评估肺癌、直结肠癌及前列腺癌，确定癌症诊断后的病因别死亡率。

　　结果显示，在整个20年的随访过程中，有2,885名男性被诊断为前列腺癌、肺癌或直结肠癌，769名死亡。在校正吸烟、体重指数及年龄后，与处于最低CRF五分位数的男性相比，处于最高五分位数者中偶发性肺癌、直结肠癌和前列腺癌的危险比分别为0.32(P＜0.001)、0.62(P=0.05)和1.13(P=0.14)。在发生癌症的男性中，癌症特异性死亡率和心血管特异性死亡率随着所处的CRF五分位数的增加而下降(P＜0.0001)。另外，即使仅有MET 增加，死于癌症和心血管疾病的风险也分别下降14%和23%(HR，0.86；HR， 0.77；P均＜0.001)。

Men’s Fitness in Middle Age Protects against Developing and Dying from Cancer Later in Life
Findings from a large, prospective 20-year study indicate that a high level of cardiovascular fitness in middle age reduces men‟s risk of developing and dying from lung and colorectal cancer, two of the most common cancers affecting men. Better fitness also reduces the risk of dying from, though not developing, prostate cancer.
“While poor fitness is already known to predict future cardiovascular disease, this is the first study to explore fitness as a marker of future cancer risk prognosis,” said lead study author Susan Lakoski, MD, assistant professor of medicine at the University of Vermont. “This finding makes it clear that patients should be advised that they need to achieve a certain fitness level, and not just be told that they need to exercise. And unlike exercise behavior, which relies on patient self-reporting, fitness can be objectively and accurately measured in a clinical setting.”
The study included 17,049 men who had a single cardiovascular fitness assessment as part of a specialized preventive health check-up visit at a mean age of 50 years offered at the Cooper Institute. The fitness test, which is similar to a stress test for heart disease risk, entailed walking on treadmill under a regimen of changing speed and elevation. The men‟s performance was recorded in established units of fitness called metabolic equivalents or METs. Study participants were divided into five groups (quintiles) according to their fitness performance.
Researchers subsequently analyzed Medicare claims data to identify the participants of this study who had developed lung, colorectal, or prostate cancer – the three most common types of cancer among U.S. men. Over a median follow-up period of 20-25 years, 2,332 men were diagnosed with prostate cancer, 276 were diagnosed with colorectal cancer, and 277 were diagnosed with lung cancer. There were 347 deaths due to cancer and 159 men died of cardiovascular disease.
Researchers found that the risk of being diagnosed with lung or colorectal cancer was reduced by 68 and 38 percent, respectively, in men who were the most fit, relative to those who were the least fit. Fitness did not significantly impact prostate cancer risk. In the analysis, data were adjusted for smoking and other factors, such as body mass index and age.
Among the men who developed cancer, those who were more fit at middle age had a lower risk of dying from all the three cancers studied, as well as cardiovascular disease. Even a small improvement in fitness (by 1MET) made a significant difference in survival ─ reducing the risks of dying from cancer and cardiovascular disease by 14 and 23 percent, respectively.
Another interesting finding was that men who had low fitness had an increased risk of cancer and cardiovascular disease even if they were not obese. This suggests that patients should focus on improving their fitness, regardless of their body weight. Adequate fitness level depends on gender and age. In this study, men who fell in the lowest quintile for fitness achieved less than 13.5 minutes during the treadmill exercise test if they were 40-49 years old, less than 11 minutes if they were 50-59, and less than 7.5 minutes if they were 60 or older.
ASCO Perspective: “This important study establishes cardiorespiratory fitness as an independent and strong predictor of cancer risk and prognosis in men. While more research is needed to determine if similar trends are
valid in relation to other cancers and among women, these results indicate that people can reduce their risk of cancer with relatively small lifestyle changes,” said ASCO President Sandra M. Swain, MD, FACP.
This research was supported by the National Cancer Institute.