XXXX : detection of occult metastases in regional lymph nodes by a polymerase chain reaction-based assay.

@entity1 @entity788 @entity5 @entity984 @entity3 @entity420
BACKGROUND: Stage I (T1-2NOM0) @entity420 is associated with a 5-year survival rate of 15-25%. Despite apparently curative resection and pathologic staging indicating localized disease, these @entity5 recur. The authors hypothesized that there exists microscopic regional disease that is not detected by surgical exploration or routine histopathology. METHODS: Because 90-95% of @entity788 exhibit codon 12 @entity984 mutations, the authors examined regional lymph nodes for mutated @entity984 as a marker of @entity3 . DNA was extracted from paraffin embedded archival specimens (primary @entity5 and histologically negative lymph nodes) of @entity1 with Stage I @entity788 . The target region of @entity984 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 @entity984 and resected jejunum or gallbladder were used as controls. The regional lymph nodes of 22 @entity1 whose @entity5 harbored mutated @entity984 were tested. RESULTS: Dilution experiments with normal and mutant control cell line DNA demonstrated an assay sensitivity for mutated @entity984 of 0.1%. Mutated @entity984 was found in at least 1 regional lymph node in 16 (73%) of 22 @entity1 with pathologic Stage I @entity788 , which suggested metastases not detected by routine histopathology. DNA sequence analysis was performed in four @entity1 and confirmed identical point mutations in the @entity5 and accompanying PCR/RFLP positive lymph nodes. CONCLUSIONS: Pathologic examination of regional lymph nodes in @entity788 specimens fails to detect metastases in many @entity1 . Lymph node micrometastasis is one reason for the poor survival rates observed among @entity1 with @entity5 . PCR/RFLP may have a role in staging early @entity788 .
