Curtin Karen, Slattery Martha L, Holubkov Richard, Edwards Sandra, Holden Joseph A, Samowitz Wade S
Health Research Center, Department of Family and Preventive Medicine, University of Utah, Salt Lake City, UT 84108, USA.
Appl Immunohistochem Mol Morphol. 2004 Dec;12(4):380-6. doi: 10.1097/00129039-200412000-00017.
This study compares single-strand conformation polymorphism (SSCP)/sequencing and immunohistochemistry (IHC) in a population-based colon cancer study to determine the best methods to evaluate p 53 alterations in tumors. Epidemiologic data collected from the Utah portion of a multicenter case-control study of colon cancer (n = 268) was used to compare somatic p53 mutations detected using SSCP/sequencing of exons 5 through 8 with those with p53 protein overexpression detected by IHC. A total of 136 tumors (51%) had p 53 mutations identified using SSCP/sequencing. IHC detected 164 tumors (61%) with protein overexpression (using a cut point of > or =20% positive cells) and 142 tumors (53%) when > or =50% positive cells were used. Sensitivity of IHC (> or =20% level) using SSCP/sequencing as the reference method was 85%. Specificity of IHC (> or =20% level) using SSCP/sequencing as reference was 63%. When > or =50% positive cells were used, specificity increased to 77%. Associations with age, gender, tumor site, stage, and Ki-ras were similar for both methods. An inverse relationship between microsatellite instability and p 53 was detected with the higher threshold for IHC positivity and SSCP/sequencing. SSCP/sequencing was able to discriminate between mutated p 53 and wild-type p 53 when evaluating dietary associations whereas IHC was not able to discriminate between these tumor types. Using a level of 50% or more positive cells increases specificity relative to sensitivity in comparison with lower staining levels, and is comparable with sequencing in its ability to detect an inverse relationship with the MSI. Advantages gained by sequencing are its ability to examine specific mutations and the improved ability to discriminate between cases with p 53 mutation and wild type when evaluating associations.
在一项基于人群的结肠癌研究中，本研究比较了单链构象多态性（SSCP）/测序和免疫组织化学（IHC），以确定评估肿瘤中p53改变的最佳方法。从一项多中心结肠癌病例对照研究的犹他州部分收集的流行病学数据（n = 268）用于比较通过外显子5至8的SSCP/测序检测到的体细胞p53突变与通过IHC检测到的p53蛋白过表达的突变。使用SSCP/测序共鉴定出136个肿瘤（51%）有p53突变。IHC检测到164个肿瘤（61%）有蛋白过表达（使用≥20%阳性细胞的切点），当使用≥50%阳性细胞时检测到142个肿瘤（53%）。以SSCP/测序作为参考方法，IHC（≥20%水平）的敏感性为85%。以SSCP/测序作为参考，IHC（≥20%水平）的特异性为63%。当使用≥50%阳性细胞时，特异性增加到77%。两种方法与年龄、性别、肿瘤部位、分期和Ki-ras的关联相似。在IHC阳性和SSCP/测序的较高阈值下，检测到微卫星不稳定性与p53之间呈负相关。在评估饮食关联时，SSCP/测序能够区分突变的p53和野生型p53，而IHC无法区分这些肿瘤类型。与较低的染色水平相比，使用50%或更多阳性细胞的水平可提高特异性相对于敏感性的比例，并且在检测与微卫星不稳定性的负相关关系方面与测序相当。测序的优势在于其能够检查特定突变，以及在评估关联时区分p53突变病例和野生型的能力得到提高。
