微卫星多态性分析鉴别非小细胞肺癌术后肺内转移与第二原发癌

Distinguishing second primary tumors from lung metastasis in patients with postoperative non-small cell lung cancer by microsatellite analysis

目的利用微卫星多态性分析探寻非小细胞肺癌(NSCLC)术后肺内复发转移与第二原发肿瘤(Second primary tumor,SPT)的分子遗传学差异以助鉴别诊断。方法 1994年1月至2002年8月接受手术治疗的21例Ⅰ～Ⅲ_A 期 NSCLC 患者,术后2～7年(中位2.8年)发现病理类型与原发 NSCLC 相同的肺内孤立肿瘤(腺癌7例,鳞癌14例),将之与相应的原发 NSCLC 石蜡包埋组织配对,以非恶性肺组织为对照,在显微组织切割基础上分离其 DNA,应用 PCR 为基础的微卫星分析方法检测8个定位于染色体3p、9p 及17p 区域的高密度微卫星位点,确定每一位点在相应配对肿瘤组织中杂合性丢失的异同,并结合临床特点分析肺内孤立肿瘤是复发转移还是 SPT。结果根据临床及影像学特点,9例患者肺内孤立肿瘤转移的可能性较大,其中7例配对肿瘤组织在3p、9p 及17p 8个微卫星标志上等位基因杂合性丢失的位点相同,提示肺内孤立肿瘤与原发 NSCLC 具有共同的克隆起源,支持肺内转移癌的诊断。4例肺内孤立肿瘤患者的临床病理及影像学特点倾向 SPT,其配对肿瘤3p、9p 及17p 上8个微卫星位点等位基因杂合性丢失条带不一致,表明肺内孤立肿瘤克隆起源相异于原发 NSCLC,支持临床 SPT 的诊断。另8例肺内孤立肿瘤患者术前不能判定系 SPT 还是肺内转移,其中6例配对组织3p 或3p 与17p 微卫星位点杂合性丢失模式一致,但9p 或17p 杂合性丢失不一致,临床随访发现该6例肺内孤立肿瘤术后6～13个月内可见肺内或远处转移,支持肺内孤立肿瘤为转移癌的诊断;2例配对肿瘤虽有一致的9p 或17p 微卫星位点杂合性丢失,但3p 的杂合性丢失模式不一致,临床倾向 SPT。结论对 NSCLC 术后肺内孤立病灶,3p、9p、17p 微卫星多态性分析其等位基因杂合性丢失有助于鉴别系肺内转移还是 SPT,其中3p 的杂合性丢失可能是鉴别诊断的重要生物学标志,需扩大样本进一步研究。

Objective In patients with resected early stage non-small cell lung cancer（ NSCLC）, intrapulmonary solitary tumor represents either second primary tumor（SPT） or a metastasis. This study is to discern SPT from lung metastasis in patients with postoperative NSCLC followed a solitary intrapulmonary tumor by microsatellite analysis. Methods Twenty-one patients with stage Ⅰ-ⅢA NSCLC resected by surgery during 1994. 1 - 2002. 8 were studied. Paired tumors from 21 patients with NSCLC and a solitary lung nodule were analyzed for their loss of heterozygosity（LOH） on chromosomal arms 3p, 9p and 17p. DNA from microdissectad tumors and non-malignant lung tissues was subjected to polymerase chain reactionbased microsatellite analysis using 8 microsatellite markers. An effort was also made to distinguish SPT from lung metastasis on the basis of clinical and histopathologic features. Results The paired tumors from 7 patients had concordant patterns of LOH at all microsatellite loci suggesting the same clonal origin, and supporting metastatic spread, where 4 paired rumors had discordant patterns of at all loci suggesting independent tumor origin. These observations were supported by the clinical and pathologic findings. Additional 6 paired tumors had concordant allelic loss on 3p and discordant loss on the other, clinical characteristics supporting metastatic disease. In contrast, 2 paired tumors had concordant allelic loss on 9p or 17p but discordant loss on the 3p, clinical data supporting SPT. Conclusions The paired tumors from 7 patients had concordant patterns of LOH at all microsatellite loci suggesting the same clonal origin, and supporting metastatic spread, where 4 paired tumors had discordant patterns of at all loci suggesting independent tumor origin. These observations were supported by the clinical and pathologic findings. Additional 6 paired tumors had concordant allelic loss on 3p and discordant loss on the other, clinical characteristics supporting metastatic disease. In contrast, 2 paired tumors had concordant allelic loss on 9p or 17p but discordant loss on the 3p, clinical data supporting SPT.