Demeure M J, Doffek K M, Komorowski R A, Wilson S D
Department of Surgery, Medical College of Wisconsin, Milwaukee 53226, USA.
Cancer. 1998 Oct 1;83(7):1328-34.
Stage I (T1-2NOM0) adenocarcinoma of the pancreas is associated with a 5-year survival rate of 15-25%. Despite apparently curative resection and pathologic staging indicating localized disease, these cancers recur. The authors hypothesized that there exists microscopic regional disease that is not detected by surgical exploration or routine histopathology.
Because 90-95% of pancreatic cancers exhibit codon 12 K-ras mutations, the authors examined regional lymph nodes for mutated K-ras as a marker of metastasis. DNA was extracted from paraffin embedded archival specimens (primary tumors and histologically negative lymph nodes) of patients with Stage I pancreatic adenocarcinoma. The target region of K-ras was amplified by polymerase chain reaction (PCR) and tested for codon 12 mutation by BstN1 restriction digestion (restriction fragment length polymorphism [RFLP]) that recognized normal but not mutated sequences. Cell lines that harbored normal or mutated K-ras and resected jejunum or gallbladder were used as controls. The regional lymph nodes of 22 patients whose tumors harbored mutated K-ras were tested.
Dilution experiments with normal and mutant control cell line DNA demonstrated an assay sensitivity for mutated K-ras of 0.1%. Mutated K-ras was found in at least 1 regional lymph node in 16 (73%) of 22 patients with pathologic Stage I pancreatic adenocarcinoma, which suggested metastases not detected by routine histopathology. DNA sequence analysis was performed in four patients and confirmed identical point mutations in the primary tumor and accompanying PCR/RFLP positive lymph nodes.
Pathologic examination of regional lymph nodes in pancreatic adenocarcinoma specimens fails to detect metastases in many patients. Lymph node micrometastasis is one reason for the poor survival rates observed among patients with Stage I cancers. PCR/RFLP may have a role in staging early pancreatic cancers.
I期（T1 - 2N0M0）胰腺腺癌的5年生存率为15% - 25%。尽管进行了看似根治性的切除且病理分期显示为局限性疾病，但这些癌症仍会复发。作者推测存在未被手术探查或常规组织病理学检测到的微小区域疾病。
由于90% - 95%的胰腺癌存在密码子12的K - ras突变，作者检测区域淋巴结中突变的K - ras作为转移的标志物。从I期胰腺腺癌患者的石蜡包埋存档标本（原发肿瘤和组织学阴性的淋巴结）中提取DNA。通过聚合酶链反应（PCR）扩增K - ras的目标区域，并通过识别正常但非突变序列的BstN1限制性消化（限制性片段长度多态性[RFLP]）检测密码子12突变。携带正常或突变K - ras的细胞系以及切除的空肠或胆囊用作对照。对22例肿瘤携带突变K - ras患者的区域淋巴结进行检测。
正常和突变对照细胞系DNA的稀释实验表明，该检测对突变K - ras的灵敏度为0.1%。在22例病理I期胰腺腺癌患者中，16例（73%）的至少1个区域淋巴结中发现了突变的K - ras，这表明存在未被常规组织病理学检测到的转移。对4例患者进行了DNA序列分析，证实原发肿瘤和伴随的PCR/RFLP阳性淋巴结中存在相同的点突变。
胰腺腺癌标本区域淋巴结的病理检查未能在许多患者中检测到转移。淋巴结微转移是I期癌症患者生存率低的原因之一。PCR/RFLP可能在早期胰腺癌分期中发挥作用。
