Mutations of tumor suppressor genes and/or oncogenes are frequently identified in human cancers. These mutations often appear before detectable morphological changes. Identification of the mutational profile may be a useful indicator to:
- Compare the mutational fingerprint of two or more sites of cancer to determine whether the neoplastic deposits are representative of a recurrence/metastasis of cancer or a new primary (independent) cancer.
- Define the primary site of formation in relationship to multiple sites of metastatic spread.
- Differentiate multicentric carcinoma versus intra-organ spread of one cancer.
- Differentiate local recurrence of cancer versus new primary cancer formation.
- Define the presence or absence of cancer in atypical cytology by comparing the mutational fingerprint with that of known previous cancer.
Specimens derived from solid tumors including colorectal, lung, breast, gynecologic, and liver are appropriate for this analysis.
Microdissection to obtain minute representative areas of cellular atypia followed by polymerase chain
reaction (PCR) / Fragment based analysis for loss of heterozygosity (LOH) using a panel of microsatellite markers in proximity to 16 tumor suppressor genes including P16, PTEN, TP53, VHL, DPC4, and OGG1.
Analysis of oncogenes and additional markers of tumor suppressor genes may be added to the panel depending on the type of organ, tissue, or histopathology.