Department of Cancer Biology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina, USA.
Cancer Epidemiol Biomarkers Prev. 2012 Oct;21(10):1768-73. doi: 10.1158/1055-9965.EPI-12-0585. Epub 2012 Aug 22.
Higher levels of total and ionized serum calcium have been shown to predict fatal prostate cancer in prospective studies. Because the follow-up time in these studies was relatively short, these associations could reflect the effect of clinically significant but occult prostate tumors on serum calcium levels. If this were true, prostate cancer mortality rates among men with higher levels of serum calcium should be higher during the early follow-up period and should decline thereafter.
We tested this hypothesis by estimating the relative risk of death from prostate cancer in the National Health and Nutrition Examination Survey III for incremental increases in total and ionized serum calcium using Cox proportional hazards regression with time-dependent effects.
Forty-nine (49) fatal prostate cancers occurred over 204 months of follow-up and 1,069,327 person-months of observation. Men with higher total serum calcium and higher serum ionized calcium had increased risks of fatal prostate cancer during the first 96 months of follow-up [Relative Hazard (RH) = 1.50 per 0.1 mmol/L total serum calcium, 95% confidence interval (CI) = 1.04-2.17; RH = 1.72 per 0.05 mmol/L ionized calcium, 95% CI = 1.11-2.66]. Evidence of an association between total and ionized serum calcium and prostate cancer deaths was not significant after 96 months.
Our analyses support the hypothesis that the elevated risk for fatal prostate cancer observed in men with high serum calcium is because of the presence of extant, but occult prostate cancer.
These findings have implications for the potential use of serum calcium in the detection of clinically significant prostate cancer.
前瞻性研究表明，血清总钙和离子钙水平升高可预测致命性前列腺癌。由于这些研究的随访时间相对较短，这些关联可能反映了临床上显著但隐匿性前列腺肿瘤对血清钙水平的影响。如果是这样，血清钙水平较高的男性的前列腺癌死亡率在早期随访期间应该更高，此后应该下降。
我们通过使用具有时间依赖性效应的 Cox 比例风险回归来估计 National Health and Nutrition Examination Survey III 中总血清钙和离子血清钙的递增与致命性前列腺癌死亡的相对风险，检验了这一假设。
在 204 个月的随访和 1069327 人-月的观察中，有 49 例致命性前列腺癌发生。总血清钙和血清离子钙较高的男性在前 96 个月的随访中致命性前列腺癌的风险增加[相对危险度（RH）= 0.1mmol/L 总血清钙每增加 0.1mmol/L，95%置信区间（CI）= 1.04-2.17；RH= 0.05mmol/L 离子钙每增加 0.05mmol/L，95%CI=1.11-2.66]。在 96 个月后，总血清钙和离子钙与前列腺癌死亡之间的关联没有统计学意义。
我们的分析支持这样的假设，即血清钙水平升高的男性致命性前列腺癌风险增加是由于存在现有的、但隐匿性的前列腺癌。
这些发现对潜在使用血清钙检测临床上显著的前列腺癌具有影响。
