近日,，阿姆斯特丹大學(xué)的一項(xiàng)研究表明,，在中危患者中,，第2輪糞便免疫化學(xué)試驗(yàn)(FIT)對(duì)結(jié)直腸癌的陽(yáng)性預(yù)測(cè)值(PPV)為第1輪試驗(yàn)的PPV的一半,。此外，第1輪愈創(chuàng)木脂糞便潛血試驗(yàn)的PPV與第1輪FIT無(wú)顯著差異,。相關(guān)論文發(fā)表在《胃腸病學(xué)》(Gastroenterology)雜志上,。
在這項(xiàng)研究中，阿姆斯特丹大學(xué)學(xué)術(shù)醫(yī)療中心的Maaike J. Denters博士及其同事將4,990例50~74歲的中?；颊唠S機(jī)分入愈創(chuàng)木脂糞便潛血試驗(yàn)組(n=2,119)或FIT組(n=2,871),。在將試劑盒發(fā)放給患者后,，通過(guò)郵寄形式收回。對(duì)愈創(chuàng)木脂糞便潛血試驗(yàn)組患者無(wú)飲食方面的要求,。2年后,，對(duì)第1輪試驗(yàn)結(jié)果陰性的所有患者發(fā)放FIT試劑盒。要求第1輪和第2輪試驗(yàn)結(jié)果均陽(yáng)性的患者到篩查中心接受咨詢,，并建議進(jìn)行結(jié)腸鏡檢查,，除非存在禁忌證。
共有293例患者的第1輪試驗(yàn)結(jié)果為陽(yáng)性,，其中233例來(lái)自FIT組,，60例來(lái)自愈創(chuàng)木脂組,。因此,，F(xiàn)IT組和愈創(chuàng)木脂組的陽(yáng)性率分別為8.1%和2.8%。共239例陽(yáng)性患者進(jìn)行結(jié)腸鏡檢查,。在愈創(chuàng)木脂組53 例陽(yáng)性患者中,，24例患者的最終結(jié)果為晚期腺瘤，表明對(duì)晚期腺瘤的PPV為45%(晚期腺瘤定義為≥10 mm的任何腺瘤,，或伴有20%以上的絨毛成分,，或伴有高度異型增生)；8例患者檢出結(jié)直腸癌,，表明對(duì)癌癥的PPV為15%,。在FIT組186例陽(yáng)性患者中，88例檢出晚期腺瘤(PPV=47%),，12例檢出癌癥(PPV=6%),。總體而言,，在第1輪所有陽(yáng)性患者中,，共20例患者檢出癌癥，提示對(duì)癌癥的PPV為8%,。
在愈創(chuàng)木脂糞便潛血試驗(yàn)后進(jìn)行FIT的患者中,，有122例患者在第2輪試驗(yàn)結(jié)果為陽(yáng)性后進(jìn)行了結(jié)腸鏡檢查，其中53例檢出晚期腺瘤(PPV=43%),，5例檢出癌癥(PPV=4%),。同樣，在FIT后再次進(jìn)行FIT的患者中,，50例檢出晚期腺瘤(PPV=38%),，4例檢出癌癥(PPV=3%)。在第2輪中,，共9例患者檢出癌癥(癌癥例數(shù)為第1輪的一半),，表明對(duì)癌癥的PPV僅為4%,。盡管第2輪篩查對(duì)結(jié)直腸癌的PPV明顯降低，但該輪篩查檢出的腺瘤數(shù)量較多,。
與其他研究采用的提示FIT陽(yáng)性的血紅蛋白閾值(75 ng/ml或100 ng/ml)相比,，該研究所采用的閾值(50 ng/ml)較低，這可能是該研究的局限性所在,。研究者表示,，在這一閾值進(jìn)行更多輪的篩查將很可能觀察到仍然較高的陽(yáng)性率，因此需進(jìn)行的結(jié)腸鏡檢查也較多,，而PPV將進(jìn)一步降低,。閾值的選擇對(duì)于平衡這2個(gè)參數(shù)至關(guān)重要，并且受到經(jīng)濟(jì),、行為和其他因素的影響,，而且不同國(guó)家選擇的閾值也各不相同。（生物谷Bioon.com）
doi:10.1053/j.gastro.2011.11.024
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Lower Risk of Advanced Neoplasia Among Patients With a Previous Negative Result From a Fecal Test for Colorectal Cancer
Maaike J. Denters, Marije Deutekom, Patrick M. Bossuyt, An K. Stroobants, Paul Fockens, Evelien Dekker
Background & Aims
Consecutive rounds of fecal occult blood tests (FOBTs) are used to screen for colorectal cancer (CRC); they detect precursor lesions and early-stage disease. We assessed whether the positivity rate and the positive predictive values (PPVs) for advanced neoplasia and CRC decrease with repeated testing by using fecal immunochemical tests (FITs).
Methods
Data were collected from 2 rounds of screening. In the first round, average-risk persons (50 to 74 years old) were randomly assigned to groups that received the guaiac FOBT or FIT. In the second round, the subjects received only FIT (1594 received FIT after guaiac FOBT and 2022 received FIT after FIT). The positivity rate and PPV for advanced neoplasia and CRC were compared between second-round participants with a previous negative test result (FIT after guaiac FOBT or FIT after FIT) and first-round participants (guaiac FOBT or FIT).
Results
The rate of positive results from FIT was 7.4% in the FIT-after-FIT group, compared with 8.1% in the first-round FIT group (P = .34). A significant decrease was observed in the PPV for advanced neoplasia between the first and second round from 55% (132/239) to 44% (112/252; P = .017). The PPV for CRC was 8% (20/239) in the first round versus 4% (9/252) in the second round (P = .024). Ten interval cancers were diagnosed. There were no significant differences in stages of cancers detected in the first and second round or the interval cancers.
Conclusions
The rate of positive results from FIT does not decrease after repeated CRC screening, but the PPVs of FIT for advanced neoplasia and for CRC are significantly lower among second-round participants who tested negative in the first round.
