Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts;
Clin Epidemiol. 2010 Oct 22;2:241-6. doi: 10.2147/CLEP.S13811.
Translational epidemiology studies often use archived tumor specimens to evaluate genetic hypotheses involving cancer outcomes. When the exposure of interest is a germline polymorphism, a key concern is whether the genotype assayed from tumor-derived DNA is representative of the germline. We evaluated the concordance between breast tumor-derived and normal lymph node-derived genotypes for three polymorphic tamoxifen-metabolizing enzymes.
We assayed paired DNA samples extracted from archived tumor and normal lymph node tissues from 106 breast cancer patients. We used TaqMan assays to determine the genotypes of three enzyme variants hypothesized to modify tamoxifen effectiveness, ie, CYP2D64, UGT2B152, and UGT1A8*2. We assessed genotype agreement between the two DNA sources by calculating the percent agreement and the weighted kappa statistic.
We successfully obtained genotypes for CYP2D64, UGT2B152, and UGT1A82 in 99%, 100%, and 84% of the paired samples, respectively. Genotype concordance was perfect for the CYP2D64 and UGT1A82 variants (weighted kappa for both = 1.00; 95% confidence interval [CI] 1.00, 1.00). For UGT2B152, one pair out of 106 gave a discordant result that persisted over several assay repeats.
We observed strong agreement between DNA from breast tumors and normal lymphatic tissue in the genotyping of polymorphisms in three tamoxifen-metabolizing enzymes. Genotyping DNA extracted from tumor tissue avoids the time-consuming practice of microdissecting adjacent normal tissue when other normal tissue sources are not available. Therefore, the demonstrated reliability of tumor-derived DNA allows resources to be spent instead on increasing sample size or the number of polymorphisms examined.
转化流行病学研究常利用存档的肿瘤标本来评估与癌症结局相关的遗传假说。当感兴趣的暴露是种系多态性时，一个关键问题是从肿瘤衍生 DNA 中检测到的基因型是否代表种系。我们评估了三种多态性他莫昔芬代谢酶的乳腺癌衍生肿瘤和正常淋巴结衍生基因型之间的一致性。
我们检测了 106 例乳腺癌患者存档的肿瘤和正常淋巴结组织提取的配对 DNA 样本。我们使用 TaqMan 测定法来确定三种被假设为改变他莫昔芬疗效的酶变体的基因型，即 CYP2D64、UGT2B152 和 UGT1A8*2。我们通过计算百分比一致性和加权 kappa 统计量来评估两种 DNA 来源的基因型一致性。
我们成功地获得了 99%、100%和 84%配对样本中 CYP2D64、UGT2B152 和 UGT1A82 的基因型。CYP2D64 和 UGT1A82 变体的基因型一致性非常完美（两个变体的加权 kappa 值均为 1.00；95%置信区间[CI]为 1.00，1.00）。对于 UGT2B152，106 对中有一对出现不一致的结果，且在几次重复检测中都存在。
我们观察到三种他莫昔芬代谢酶多态性基因分型中，来自乳腺癌肿瘤和正常淋巴组织的 DNA 之间具有很强的一致性。当其他正常组织来源不可用时，从肿瘤组织中提取的 DNA 进行基因分型可避免耗时的对相邻正常组织进行显微解剖的做法。因此，所证明的肿瘤衍生 DNA 的可靠性可以使资源用于增加样本量或检查的多态性数量。
