Authors' response to Eluri et al. letter to the editor regarding: Colorectal cancer prevention by an optimized colonoscopy protocol in routine practice.
Authors' response to Eluri et al. letter to the editor regarding: Colorectal cancer prevention by an optimized colonoscopy protocol in routine practice.
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作者对 Eluri 等人的回应。
DOI：
10.1002/ijc.29472
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发表时间：
2015
影响因子：
6.4
通讯作者：
deGroen,PietC
中科院分区：
文献类型：
--
作者：
Xirasagar,Sudha;deGroen,PietC
Eluri等人指出，“观察到的结直肠癌CRC的显著减少主要是由于研究设计中的固有偏倚，而不是改进的筛查。”他们强烈反对排除首次结肠镜检查发现的癌症病例。我们不同意有两个原因。首先，为了评估结肠镜检查作为CRC预防工具的效果，在初次结肠镜检查时排除已经患有癌症的患者是不言自明的。我们不是唯一这样做的小组;几乎所有关于结肠镜检查疗效的研究都排除了初次结肠镜检查时发现的癌症，从1993年的国家息肉研究开始，1到2013年Nishihara等人的最新研究2，以及2014年Loberg等人的最新研究3。与我们的研究类似，这些研究使用普通人群作为对照组，因为缺乏精确可比的对照组。其次，与Winawer等人的早期研究不同，1我们的“对照”人群是剩余的南卡罗来纳州人群，他们正在接受结肠镜检查的部分筛查。这意味着在对照组中已经预防了大量的癌症，表明我们观察到的癌症预防率低估了真实效果。Eluri等人提出了一个关于我们的研究队列和普通人群之间基线CRC风险不平衡的担忧，并建议我们的研究应该包括研究队列中基线发现的癌症病例，以调整普通人群中无症状的癌症。他们引用了Pabby等人，4 Atkin et al. 5和Kahi et al. 6作为在研究队列中纳入基线癌症病例的例子。然而，这三项研究中有两项没有这样做。Pabby等人4报告了饮食息肉预防试验中间期癌症的发生率和特征，该试验包括基线时患有腺瘤的患者，并排除了基线时患有CRC的患者（参见Schatzkin等人）。7该研究没有报告相对于比较人群的标准化发病率。与“无症状癌症”概念最接近的是他们将一些间隔癌症病例分类为基线时可能遗漏的癌症。Leung等人8报告了在同一试验队列中获得的标准化发病率比，随访时间长于Pabby等人。
Eluri et al. state that the “marked observed reduction in colorectal cancer CRC is largely due to an inherent bias in study design rather than improved screening.” They strongly object to excluding cancer cases found at first colonoscopy. We disagree for two reasons. First, in order to assess the effect of colonoscopy as a CRC prevention tool, it is axiomatically essential to exclude patients who already have cancer at the time of the initial colonoscopy. We are not the only group to have done this; almost all studies of colonoscopy efficacy have excluded cancers found at initial colonoscopy, starting with the National Polyp Study of 1993, 1 through the recent study by Nishihara et al. 2 in 2013, and the most recent by Loberg et al. 3 in 2014. Similar to our study, these studies used the general population as the comparison group for lack of a precisely comparable control group. Second, unlike earlier studies such as Winawer et al., 1 our “control” population was the remaining South Carolina population that was being partially screened with colonoscopy. This means that a significant number of cancers were already being prevented in the control group, indicating that our observed cancer prevention rate is an underestimate of the true effect.Eluri et al. raise a concern about an imbalanced CRC risk at baseline between our study cohort and the general population, and suggest that our study should include cancer cases found at baseline in the study cohort to adjust for asymptomatic cancers in the general population. They cite Pabby et al., 4 Atkin et al. 5 and Kahi et al. 6 as examples of those that included cancer cases at baseline in the study cohorts. However, two of these three studies did not do so. Pabby et al. 4 reported the occurrence and characteristics of interval cancers in the dietary Polyp Prevention Trial which included patients with adenomas at baseline and excluded patients with CRC at baseline (refer Schatzkin et al.). 7 The study did not report standardized incidence ratios relative to comparison populations. The nearest approximation to the concept of “asymptomatic cancers” is their classification of some of the interval cancer cases as probable missed cancers at baseline. Leung et al. 8 reported standardized incidence ratios obtained on the same trial cohort with a longer follow-up than Pabby et al.