BETA CAROTENE AND NON MELANOMA SKIN CANCER IN THE PHS

我们建议在医师健康研究（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，这是一项针对22,071名年龄在40-84岁的美国男性医生的阿司匹林和β -胡萝卜素的随机试验。试验开始于1982年，随机期结束于1995年12月，平均13年的随机化，主要是在1982年，从14,916名无心肌梗塞，中风或癌症（不包括非黑色素瘤皮肤癌）的试验参与者开始。这些都在零下82摄氏度的环境中保存和储存。在试验期间，共有3,613名医生报告发生了NMSC事件。其中，2541人提供了基线血浆标本。采用嵌套病例-对照设计，我们将分析1300例病例和1300例年龄和吸烟状况相匹配的对照样本。我们将检验一种假设，即补充随机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。此外，我们将确定在随机分配到β -胡萝卜素安慰剂组的患者中，NMSC的风险是否与基线血浆中β -胡萝卜素、α -生育酚或视黄醇的水平呈负相关。嵌套病例对照方法提供了一种有效的方法来检验假设，使用的血液样本是花费相当大的费用收集的，并且在PHS中保存得很好。

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.