Low-dose aspirin therapy does not appear to compromise the results of immunochemical tests for fecal occult blood, as it may with other types of FOBTs, according to a report in the Dec. 8 issue of JAMA.

The sensitivity of two different immunochemical FOBTs for detecting colorectal neoplasms was actually higher among patients taking low-dose aspirin therapy than among those not taking aspirin, particularly in cases of advanced neoplasms, said Dr. Hermann Brenner and his associates in the division of clinical epidemiology and aging research, German Cancer Research Center, Heidelberg.

Concerns have been raised that low-dose aspirin therapy might cause bleeding from upper GI lesions or insignificant colonic lesions, which would produce false-positive FOBT results. Some physicians have even called for suspension of aspirin therapy before FOBT.

But immunochemical FOBTs (iFOBTs) react to globin, which is degraded as it passes through the gastrointestinal tract. They are less likely to produce false-positives from upper GI bleeds than are the guaiac-based FOBTs that react to the heme moiety of hemoglobin, which is more stable as it passes through the digestive system.

Dr. Brenner and his colleagues assessed the relationship between aspirin therapy and iFOBT results in a large sample of adults participating in a screening colonoscopy program at 20 GI practices across southern Germany. The 1,979 study subjects (mean age, 62 years) provided stool samples before undergoing bowel preparation for colonoscopy.

A total of 233 of these subjects (12%) were taking low-dose aspirin therapy for cardiovascular prophylaxis, while the remainder had never used low-dose aspirin. The prevalence of neoplasms found on colonoscopy was similar between the two groups.

The study also found that two different iFOBTs had substantially (about 30%) higher sensitivity in detecting any neoplasm in people using aspirin therapy than in nonusers. The difference in test sensitivity was greatest in people found to have advanced malignancies, with one of the iFOBTs achieving a sensitivity of 71% among those using aspirin therapy but only a sensitivity of 36% among nonusers (P = .001).

This enhanced sensitivity was consistent across various subgroups of patients and across a broad range of cut points for test positivity. The advantages of aspirin therapy were particularly marked in men: among men taking low-dose aspirin, the sensitivity of iFOBTs was up to 46 percentage points higher than it was in men not using aspirin therapy, the investigators said (JAMA 2010;304:2513-20).

In contrast, the specificity of iFOBTs was slightly (about 5%) lower in people using aspirin therapy than in nonusers.

These findings indicate that “there is no need to stop low-dose aspirin use prior to undergoing iFOBT,” Dr. Brenner and his associates said.

“On the contrary, our results may even raise the provocative suggestion of whether temporary use of low-dose aspirin might be considered to enhance performance of iFOBTs,” they said.

Given their findings, temporary use of low-dose aspirin might yield a sensitivity for detecting advanced neoplasms of 60%-70% at a specificity of approximately 90% – levels of sensitivity and specificity that exceed those of other established stool tests and that “might come close to the sensitivity of sigmoidoscopy,” the researchers noted.

However, it would be premature to make such a recommendation before these findings are replicated in other populations “and followed up in further research, ideally including randomized trials and different types of FOBTs,” they added.

This study was somewhat limited in that despite the large sample size, there were few advanced neoplasms, resulting in broad confidence intervals around some estimates of iFOBT performance, Dr. Brenner and his colleagues said.

The study was supported in part by the German Research Foundation and the German Federal Ministry of Education and Research. The test kits were provided free of charge by the manufacturer. Dr. Brenner reported that the German Cancer Research Center has received funding from Eiken Chemical to evaluate an iFOBT that was not included in this analysis. Also, a patent application was filed at the European Patent Office for the combination of low-dose aspirin use and iFOBTs in early detection of colorectal neoplasms.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

德国癌症研究中心Hermann Brenner博士在12月8日出版的《美国医学会杂志》上发表报告称，虽然低剂量阿司匹林治疗可能对其他粪便隐血试验(FOBTs)结果有所影响，但并不干扰免疫化学法粪便隐血试验(iFOBTs)结果。

目前，许多医生因担忧低剂量阿司匹林治疗会导致上消化道病变或无临床意义的结肠病变出血可能会导致FOBTs假阳性结果，故在试验之前要求暂停阿司匹林治疗。研究者为分析低剂量阿司匹林治疗与iFOBT结果之间的关系，对1,979例受试者(平均年龄62岁)在进行结肠镜检查之前的粪便样本进行两种不同的iFOBTs，其中233例(12%)服用低剂量阿司匹林作为心血管疾病预防用药，其他受试者没有服用阿司匹林。

结果显示，两组受试者肠镜肿瘤检出率相似。两种不同的iFOBTs方法对阿司匹林治疗者的肿瘤检出灵敏度显著(约30%)高于非阿司匹林治疗者。而对于进展期恶性肿瘤患者，灵敏度差异最为明显，其中一种iFOBTs方法对阿司匹林治疗者的灵敏度为71%，而对非阿司匹林治疗者仅为36% (P = 0.001)。在不同亚组间以及宽泛的检测阳性界值范围内一致，iFOBTs方法均呈现较高的灵敏度。接受阿司匹林治疗的男性受试者iFOBTs灵敏度提高更为明显，比非阿司匹林治疗男性高出46%。然而阿司匹林治疗者iFOBTs特异性略低于(约 5%)非阿司匹林治疗者。(JAMA 2010;304:2513-20)。

研究表明，低剂量阿司匹林治疗对iFOBTs结果没有干扰，在进行iFOBT之前无需停止低剂量阿司匹林治疗。相反，在iFOBTs之前临时服用低剂量阿司匹林还可能提高iFOBTs灵敏度。

该研究由德国研究基金会和德国联邦教育与研究部部分资助。检测试剂盒由生产商免费提供。研究者已向欧洲专利局提交有关结直肠肿瘤检测前联合应用低剂量阿司匹林和iFOBTs的专利申请。

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