Objective: To evaluate the diagnostic performance of quantitative fecal immunochemical testing (FIT) and to provide reference for designing effective colorectal cancer (CRC) screening strategy in China. Methods: Based on an ongoing randomized controlled trial comparing the colorectal cancer screening strategies, this current study involved 3 407 participants aged 50-74 years who had undergone colonoscopies. All the feces samples were collected from the participants prior to receiving the colonoscopy. Fecal hemoglobin (Hb) was tested by FIT following a standardized operation process. Diagnosis-related indicators of FIT were calculated using the colonoscopy results as the gold standard. Results: Among the 3 407 participants, the mean age (SD) as 60.5 (6.3) years and 1 753 (51.5%) were males. The participants involved 28 (0.8%) CRCs, 255 (7.5%) advanced adenomas, 677 (19.9%) nonadvanced adenomas, and 2 447 (71.8%) benign or negative findings. With an overall positivity rate of 2.8% (96/3 407) at the recommended cutoff value of 20 μg Hb/g, the sensitivities of FIT for both CRC and advanced adenoma were 57.1% (95%CI: 37.2%-75.5%) and 11.0% (95%CI: 7.4%-15.5%), respectively, with the corresponding specificity as 98.4% (95%CI: 97.8%-98.8%). At a decreased cut-off value of 5 μg Hb/g, the sensitivities for detecting CRC and advanced adenoma increased to 64.3% (95%CI: 44.1%-81.4%) and 16.5% (95%CI: 12.1%-21.6%), respectively, but the specificity reduced to 95.2% (95%CI: 94.4%-95.9%). The areas under the ROC curve for CRC and advanced adenoma were 0.908 (95%CI: 0.842-0.973) and 0.657 (95%CI: 0.621-0.692), respectively. Of the diagnostic performance, there were no significant differences noticed by different sex and age groups. Conclusions: In our study, the quantitative FIT showed modest sensitivity in detecting CRC but limited sensitivity in detecting advanced adenoma. In population-based CRC screening programs, the quantitative FIT had the advantage of adjusting the positive threshold based on the targeted detection rate and available resource load of colonoscopy.
目的： 评价定量免疫粪便隐血试验（FIT）对进展期结直肠肿瘤（结直肠癌和进展期腺瘤）的筛检效能，为进一步优化中国人群结直肠癌筛查策略提供理论参考。 方法： 基于1项正在开展的人群结直肠癌筛查随机对照试验，选取3 407例已完成结肠镜检查的50~74岁受试者作为研究对象。所有受试者在结肠镜检查前均提供粪便标本。采用定量FIT通过标准化操作流程对所有粪便标本进行检测。以结肠镜和病理结果作为金标准，计算定量FIT对进展期结直肠肿瘤的筛检效能指标。 结果： 3 407例受试者中男性占51.5%（n=1 753），年龄为（60.5±6.3）岁，共包括结直肠癌28例（0.8%）、进展期腺瘤255例（7.5%）、非进展期腺瘤677例（19.9%）、良性病变和正常者2 447例（71.8%）。当采用厂家推荐阳性截断值（20 μg Hb/g）时，总体FIT阳性率为2.8%（96/3 407），对于结直肠癌和进展期腺瘤的灵敏度分别为57.1%（95%CI：37.2%~75.5%）和11.0%（95%CI：7.4%~15.5%），特异度为98.4%（95%CI：97.8%~98.8%）。当阳性截断值调整至5 μg Hb/g时，定量FIT对于结直肠癌和进展期腺瘤的灵敏度分别增加至64.3%（95%CI：44.1%~81.4%）和16.5%（95%CI：12.1%~21.6%），特异度降低至95.2%（95%CI：94.4%~95.9%）。受试者工作曲线分析结果显示，FIT对于结直肠癌和进展期腺瘤的曲线下面积分别为0.908（95%CI：0.842~0.973）、0.657（95%CI：0.621~0.692），且在不同性别、年龄组人群中筛检效能较为一致。 结论： 在本研究中，定量FIT对结直肠癌诊断灵敏度尚可，但对进展期腺瘤的诊断灵敏度较低。在人群结直肠癌筛查中，定量FIT的阳性截断值可以根据预设检出率及结肠镜检查负荷灵活调整，具有一定优势。.
Keywords: Colorectal neoplasm; Quantitative fecal immunochemical testing; Screening.