NUTRITIONAL PREVENTION OF CANCER

这个项目的目的是建立化学预防的潜力 补充必需的微量元素硒(Se)。这 化学预防研究项目有机会得出结论 展示了补充硒的癌症预防潜力 在中国进行的随机双盲初级癌症预防试验 美国的低饲料硒地区，因为美国的大部分地区。 人口生活在相对低硒的地区(试验的诊所位于 )，该项目的结果对公共卫生的影响是 非常相关和重要。这项试验的结果直接 适用于有非黑色素瘤皮肤病史的个体 癌症；它们也可能与其他人群相关，特别是 其他癌症风险较高的个人。这项研究可以为我们提供 补充SC有可能减少的初步证据 所有死因和癌症的死亡率以及 癌症发病率。 这项研究是一项双盲、安慰剂对照的III期癌症。 在非黑色素瘤皮肤癌高危人群中的预防试验， 用一种营养素来检验最初的试验假设 补充剂可降低癌症发病率和死亡率。人口是 自由生活且基本健康(除了有非黑色素瘤病史 皮肤癌)，并去低地七家皮肤科诊所之一就诊 美国东部沿海平原的牧草区域。该试验将 利用200微克。和400微克。剂量的SC和安慰剂。现有 在200微克上的病人。补充费将维持在该水平 剂量和新患者将被随机分配到400微克。剂量。400人 微克。剂量可以很好地分离血浆Se水平 治疗和安慰剂组，并增强统计能力 审判。 审判的外部安全监测和咨询委员会已经 建议将具体目标扩大到以下几个卫生目标 癌症发病率和死亡率。因此，具体目标是相关的。 三个问题：癌症发病率、死亡率和癌症筛查。这个 与癌症发病率相关的具体目标是：为了证明， 与安慰剂相比，补充硒将显著降低 非黑色素瘤皮肤癌(特别是鳞状细胞癌)的发病率 皮肤癌)，所有癌部位加在一起(非 黑色素瘤皮肤癌)、肺癌、前列腺癌和 结直肠癌和癌前疾病的发病率， 尤其是结直肠腺瘤性息肉。与死亡率相关的有 为了证明补充硒可以降低各种原因引起的死亡率 合并死亡和所有癌症合并死亡(特别是肺癌 癌症)。与癌症筛查相关的具体目标是实现 癌症筛查方案，特别针对结肠癌和前列腺癌 特定的抗原。其他目标是评估更高剂量的Se 补充和建立长期安全的硒 补充。

The purpose of this project is to establish the chemopreventive potential of supplementation with the essential trace element Selenium (Se). This chemoprevention research project has the opportunity to conclusively demonstrate the cancer prevention potential of Se supplementation in a randomized double-blind primary cancer prevention trial conducted in the low forage Se region of the U.S. Because the majority of the U.S. population lives in relatively low-Se areas (where the trial's clinics are located), the public health implications of this project's results are very relevant and significant. The results of this trial are directly generalizable to those individuals with a history of non-melanoma skin cancer; they may also be relevant for other populations, especially individuals at elevated risk for other cancers. This study can provide the initial evidence that Sc supplementation has the potential to decrease both mortality from all causes of death and cancer as well as the incidence of cancers. This study is a double-blind, placebo controlled phase III cancer prevention trial in a population at high risk of non-melanoma skin cancer, using a single nutrient to test the primary trial hypothesis that Se supplementation reduces cancer incidence and mortality. The population is free-living and essentially healthy (except for a history of non-melanoma skin cancer) and attends one of seven dermatology clinics in the low forage Se area of the eastern coastal plain of the U.S. The trial will utilize 200 mcg. and 400 mcg. doses of Sc as well as a placebo. Existing patients that are on the 200 mcg. supplement will be maintained at that dose and new patients will be randomized to the 400 mcg. dose. The 400 mcg. dose allows for excellent separation of plasma Se levels between the treatment and placebo groups and enhances the statistical power of the trial. The trial's external Safety Monitoring and Advisory Committee has recommended that the specific aims be expanded to the health endpoints of cancer incidence and mortality. Therefore, the specific aims are related to three issues: cancer incidence, mortality, and cancer screening. The specific aims related to cancer incidence are: to demonstrate that, compared to the placebo, Se supplementation will significantly reduce the incidence of non-melanoma skin cancer (specifically squamous cell carcinoma of the skin), that of all cancer sites combined (except non- melanoma skin cancer), the site-specific incidence of lung, prostate, and colorectal cancer, and the incidence of preneoplastic disease, specifically colorectal adenomatous polyps. Those related to mortality are to demonstrate that Se supplementation reduces mortality from all causes of death combined and from all cancers combined (specifically lung cancer). The specific aim related to cancer screening is to implement cancer screening protocols, specifically for colon cancer and prostate specific antigen. Additional aims are to evaluate higher doses of Se supplementation and to establish the long term safety of Se supplementation.