Laser microdissection and microsatellite analysis of colorectal adenocarcinomas.

Background: Microsatellite instability (MSI) is an important marker in colorectal cancer. The analysis may be difficult if the tumour is heterogeneous or only scarce material is available. The aim of this study was to apply laser microdissection (LMD) to MSI analysis in an attempt to allow diagnosis in these situations.

Materials And Methods: Twenty-two primary tumours and eight lymph node metastases from twenty patients were laser microdissected and MSI analysis was performed with an optimised multiplex PCR. Differences in allelic size between tumour and blood were evaluated to determine the MSI status.

Results: The method proved efficient in as little as 4,000 microm3 formalin-treated and paraffin-embedded tumour tissue. The result of microsatellite analysis was independent of sample location in the primary tumour and its metastasis.

Conclusion: LMD followed by a multiplex PCR is a useful method for MSI analysis in cases of tumour heterogeneity and scarce tumour material.