Clark L C, Graham G F, Crounse R G, Grimson R, Hulka B, Shy C M
Nutr Cancer. 1984;6(1):13-21.
Although experimental studies in animals show that selenium may prevent cancer, case-control studies of internal human cancers have been difficult to interpret because neoplastic tissue sequesters selenium. We therefore conducted a case-control study to examine the association between plasma selenium level and skin cancer, a neoplasm with minimal tumor mass at the time of diagnosis. The mean selenium level among patients with either basal cell epithelioma (N = 142), squamous cell carcinoma (N = 48), or both (N = 50), was 0.141 micrograms/g. This was significantly lower than the mean plasma selenium level of the 103 control subjects, which was 0.155 micrograms/g. The noncancer control groups were drawn from current clinic patients and past clinic patients. The logistic estimate of the odds ratio for the lowest versus the highest decile of selenium for all cases combined versus the group of current patient controls was 4.39; for all cases combined versus the past patient controls, the logistic estimate of the odds ratio was 5.81.
尽管动物实验研究表明硒可能预防癌症，但对人类体内癌症的病例对照研究却难以解读，因为肿瘤组织会蓄积硒。因此，我们开展了一项病例对照研究，以检验血浆硒水平与皮肤癌之间的关联，皮肤癌是一种在诊断时肿瘤块极小的肿瘤。患有基底细胞上皮瘤（N = 142）、鳞状细胞癌（N = 48）或两者皆有（N = 50）的患者的平均硒水平为0.141微克/克。这显著低于103名对照受试者的平均血浆硒水平，后者为0.155微克/克。非癌症对照组来自当前门诊患者和既往门诊患者。所有病例合并后，最低十分位数硒与最高十分位数硒相比，相对于当前患者对照组的比值比的逻辑估计值为4.39；相对于既往患者对照组，比值比的逻辑估计值为5.81。
