Gastroenterology Department, Rabin Medical Center, Beilinson Hospital, Petach Tikva, Israel.
Cancer. 2010 May 1;116(9):2115-25. doi: 10.1002/cncr.25012.
Quantified, human hemoglobin (Hb)-specific, immunochemical fecal occult blood test (IFOBT) measurements are now used for colorectal cancer (CRC) screening. The objective was to evaluate sensitivity and specificity for CRC and advanced adenomatous polyps (APs) by the fecal Hb threshold used to determine a positive test and the number of IFOBTs prepared per test, so as to determine the least number of colonoscopies required to detect a neoplasm.
Cumulative data were analyzed from a prospective cross-sectional double-blind study of 1682 consecutive, ambulatory, nonbleeding colonoscopy patients who volunteered for IFOBTs, most of above average risk, from 3 ambulatory-endoscopy centers. Fecal Hb was measured in 3 samples and analyzed by an automated instrument, and the highest result >or=50 ng Hb/mL of buffer was related to findings.
Colonoscopy identified CRC in 20 patients and advanced APs in 129. Sensitivity for either was best when any of 3 tests had >or=50 ng Hb/mL of buffer; sensitivity was 61.1% (95% confidence interval [CI], 53.2-68.9), and specificity was 87.8% (95% CI, 86.2-89.4). Positive tests identified 100% of CRCs and 55% of advanced APs every 3.1 colonoscopies. Sensitivity of a single test at the commonly used 100-ng Hb/mL threshold was lower at 31.5% (95% CI, 24.1-39.0) (P<.001), but specificity was higher at 96.4% (95% CI, 95.5-97.3) (P<.001). Positive tests identified 65% of CRCs and 26.4% of advanced APs every 2.2 colonoscopies.
The fecal Hb cutoff chosen by the screener and the number of samples collected per patient determine sensitivity and specificity for CRC/advanced AP; these factors determine the number of colonoscopies needed for positive tests and neoplasia yield. This information provides guidelines for IFOBT screening. Limitations are 1-time screening and most examinees not being at average risk for CRC.
目前，定量的、针对人血红蛋白（Hb）的免疫化学粪便隐血试验（IFOBT）已用于结直肠癌（CRC）筛查。本研究旨在通过用于确定阳性试验的粪便 Hb 阈值和每次试验准备的 IFOBT 数量来评估 CRC 和高级腺瘤性息肉（AP）的灵敏度和特异性，以确定检测到肿瘤所需的最少结肠镜检查次数。
对来自 3 个门诊内镜中心的 1682 例连续、非出血性、门诊结肠镜检查患者进行了前瞻性横断面双盲研究，这些患者自愿接受 IFOBT，大多数患者具有高于平均水平的 CRC 风险。对 3 个样本中的粪便 Hb 进行了测量，并通过自动化仪器进行了分析，且将缓冲液中 Hb 水平高于 50ng/mL 的最高值与检查结果相关联。
结肠镜检查在 20 例患者中发现 CRC，在 129 例患者中发现高级 AP。当任何 3 次检测中缓冲液的 Hb 水平均＞50ng/mL 时，两种疾病的灵敏度最佳；灵敏度为 61.1%（95%置信区间[CI]，53.2-68.9），特异性为 87.8%（95% CI，86.2-89.4）。每 3.1 次结肠镜检查可通过阳性试验识别 100%的 CRC 和 55%的高级 AP。在常用的 100ng/mL Hb 阈值下，单次检测的灵敏度为 31.5%（95% CI，24.1-39.0）（P＜0.001），但特异性为 96.4%（95% CI，95.5-97.3）（P＜0.001）。每 2.2 次结肠镜检查可通过阳性试验识别 65%的 CRC 和 26.4%的高级 AP。
筛查者选择的粪便 Hb 截止值和每位患者采集的样本数量决定了 CRC/高级 AP 的灵敏度和特异性；这些因素决定了阳性试验和肿瘤检出所需的结肠镜检查次数。这些信息为 IFOBT 筛查提供了指导。局限性在于单次筛查和大多数检查对象并非处于 CRC 的平均风险水平。
