BACKGROUND Flattened diurnal salivary cortisol patterns predict shorter subsequent survival with breast, lung, and renal cell carcinomas. The underlying cause of this flattened slope is undetermined, though it has been hypothesized to be secondary to a deficit in the amplitude of the circadian clock. To gain greater insight into the portions of the diurnal salivary curve that are associated with cancer survival, we examined (1) which points in the diurnal curve are predictive of the slope of the curve and (2) whether elevated evening cortisol levels alone are associated with reduced HPA-axis feedback inhibition (i.e., decreased sensitivity to the dexamethasone suppression test). METHOD We examined study hypotheses on adult women with advanced breast cancer (age = 54.3 ± 9.58 years; n = 99) using non-parametric Wilcoxon's rank-sum tests, Spearman correlation coefficients and an accuracy formula based on a confusion matrix. Cortisol was sampled five times per day for three consecutive days, with dexamethasone administered late on the second day. RESULTS Salivary cortisol concentrations did not vary between those with flat and steep slopes during the morning (p's > .05), but did vary in the evening (p's < 0.05). Furthermore, the concentration of the 2100h alone was 86% accurate in discriminating between individuals classified as having "flat" or "steep" slopes. Dexamethasone suppression was only associated with diurnal salivary cortisol slope (p = .0042). CONCLUSIONS Evening cortisol levels are a sensitive indicator flattened diurnal cortisol slope, suggesting evening cortisol may also be a useful predictor of breast cancer survival. Future research should focus on determining the causes of abnormally increased evening cortisol.

中文翻译：

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晚间唾液皮质醇作为转移性乳腺癌女性的单一压力标志物

背景扁平的昼夜唾液皮质醇模式预示着乳腺癌、肺癌和肾细胞癌的后续生存期较短。这种变平的斜率的根本原因尚未确定，尽管有人假设它是生物钟幅度不足的次要原因。为了更深入地了解与癌症存活率相关的昼夜唾液曲线部分，我们检查了 (1) 昼夜曲线中的哪些点可以预测曲线的斜率，以及 (2) 是否仅与夜间皮质醇水平升高有关HPA 轴反馈抑制降低（即对地塞米松抑制试验的敏感性降低）。方法 我们使用非参数 Wilcoxon 秩和检验检验了关于患有晚期乳腺癌的成年女性（年龄 = 54.3 ± 9.58 岁；n = 99）的研究假设，Spearman 相关系数和基于混淆矩阵的准确率公式。连续三天每天对皮质醇取样五次，在第二天晚些时候给予地塞米松。结果 早上平坦和陡峭斜坡之间的唾液皮质醇浓度没有变化（p > .05），但在晚上确实有所不同（p < 0.05）。此外，单独的 2100h 浓度在区分被分类为具有“平坦”或“陡峭”斜率的个体时准确率为 86%。地塞米松抑制仅与昼夜唾液皮质醇斜率相关 (p = .0042)。结论 夜间皮质醇水平是一个敏感的指标，使昼夜皮质醇斜率变平，这表明夜间皮质醇也可能是乳腺癌存活率的有用预测指标。