Sawhney Mandeep S, Farrar William D, Gudiseva Srivani, Nelson Douglas B, Lederle Frank A, Rector Thomas S, Bond John H
Section of Gastroenterology, Minneapolis VA Medical Center, Minneapolis, Minnesota 55417, USA.
Gastroenterology. 2006 Dec;131(6):1700-5. doi: 10.1053/j.gastro.2006.10.022.
BACKGROUND & AIMS: Colon cancers that develop after a complete colonoscopy may be the result of "failure of colonoscopy" or rapid tumor growth. Tumors that develop via the mismatch repair gene pathway demonstrate rapid tumor growth. The aim of this study was to determine if interval colon cancers were more likely than noninterval cancers to result from the loss of function of mismatch repair genes and hence demonstrate microsatellite instability (MSI).
We searched our institution's cancer registry for interval cancers, defined as colon cancers that developed within 5 years of a complete colonoscopy. These were frequency matched in a 1:2 ratio by age and sex to patients with noninterval cancers (defined as colon cancers diagnosed on a patient's first recorded colonoscopy). Archived cancer specimens for all subjects were retrieved and tested for MSI.
Of the 993 colon cancers diagnosed during the study period, 51 (5.1%) were identified as an interval cancer, and 112 subjects with noninterval cancer served as a comparison group. Study subjects were almost all men. MSI was found in 30.4% of interval cancers compared with 10.3% of noninterval cancers (P = .003). After adjusting for age, interval cancers were 3.7 times more likely to show MSI than noninterval cancers (95% confidence interval, 1.5-9.1). This association was strongest for tumors located in the distal colon (odds ratio, 17.5; P = .008). No difference in TNM stage at diagnosis, histologic type or grade, or 5-year survival was found between groups.
Interval colon cancers were almost 4 times as likely as noninterval colon cancers to be associated with mismatch repair gene dysfunction.
全结肠镜检查后发生的结肠癌可能是“结肠镜检查失败”或肿瘤快速生长的结果。通过错配修复基因途径发生的肿瘤表现出快速的肿瘤生长。本研究的目的是确定间期结肠癌是否比非间期癌更有可能是由于错配修复基因功能丧失导致的，从而表现出微卫星不稳定性（MSI）。
我们在本机构的癌症登记处搜索间期癌，间期癌定义为在全结肠镜检查后5年内发生的结肠癌。按年龄和性别以1:2的比例将这些患者与非间期癌患者（定义为在患者首次记录的结肠镜检查中诊断出的结肠癌）进行频率匹配。检索所有受试者的存档癌症标本并检测MSI。
在研究期间诊断的993例结肠癌中，51例（5.1%）被确定为间期癌，112例非间期癌患者作为对照组。研究对象几乎全是男性。间期癌中发现MSI的比例为30.4%，而非间期癌为10.3%（P = .003）。在调整年龄后，间期癌显示MSI的可能性是非间期癌的3.7倍（95%置信区间，1.5 - 9.1）。这种关联在位于结肠远端的肿瘤中最强（优势比，17.5；P = .008）。两组在诊断时的TNM分期、组织学类型或分级以及5年生存率方面未发现差异。
间期结肠癌与错配修复基因功能障碍相关的可能性几乎是非间期结肠癌的4倍。
