BETA CAROTENE AND NON MELANOMA SKIN CANCER IN THE PHS

我们建议在医生健康研究（PHS）中确定的非黑色素瘤皮肤癌（NMSC）病例和对照组中分析基线血液样本中的β-胡萝卜素，α-生育酚和视黄醇，PHS是一项在22，071名40-84岁的美国男性医生中进行的阿司匹林和β-胡萝卜素的随机试验。该试验开始于1982年，随机化阶段于1995年12月结束，平均随机化时间为13年，主要在1982年，来自14，916名既往无MI、中风或癌症（不包括非黑色素瘤皮肤癌）的试验参与者。它们一直保持并储存在-82摄氏度。在试验期间，共有3，613名医生报告发生NMSC事件。其中，2，541例提供了基线血浆标本。采用巢式病例对照设计，我们将分析来自1300例病例和1300例对照的样本，这些病例和对照在年龄和吸烟状况上匹配。我们将检验补充随机β-胡萝卜素的益处可能取决于血浆β-胡萝卜素的基线水平，甚至可能仅限于基线水平最低的人的假设。此外，我们将确定NMSC的风险是否与随机接受β-胡萝卜素安慰剂的患者中β-胡萝卜素、α-生育酚或视黄醇的基线血浆水平呈负相关。巢式病例对照方法提供了一种有效的方法来检验假设，使用血液样本，收集在相当大的费用和储存在PHS的巨大cre。

We propose to analyze baseline blood samples for beta-carotene, alpha- tocopherol and retinol among cases and controls of non-melanoma skin cancer (NMSC) that were ascertained in the Physicians' Health Study (PHS), a randomized trial of aspirin and beta-carotene among 22,071 U.S. male physicians aged 40-84 years. The trial begin in 1982, and the randomized period ended in December, 1995, for an average of 13 years of randomization, mostly in 1982, from 14,916 trial participants who were free from prior MI, stroke or cancer (excluding non-melanoma skin cancer). These have been maintained and stored at -82 degrees Celsius. During the trial period, a total of 3,613 physicians reported developing incident NMSC. Of these, 2,541 have provided baseline plasma specimens. Using a nested case-control design, we will analyze the specimens from a sample of 1300 cases and 1300 controls matched on age and smoking status. We will examine the hypothesis that the benefit of supplementation with randomized beta-carotene may depend on baseline levels of plasma beta-carotene, and may even be limited to those with the lowest baseline levels. In addition, we will determine whether risk of NMSC is inversely related to baseline plasma levels of beta-carotene, alpha-tocopherol, or retinol among those randomized to beta-carotene placebo. The nested case-control approaches provides an efficient means of testing hypotheses using blood samples that were collected at considerable expense and stored with great cre in the PHS.