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Medline ® Abstract for Reference 118

of 'Molecular genetics of colorectal cancer'

Low level microsatellite instability may be associated with reduced cancer specific survival in sporadic stage C colorectal carcinoma.
Wright CM, Dent OF, Newland RC, Barker M, Chapuis PH, Bokey EL, Young JP, Leggett BA, Jass JR, Macdonald GA
Gut. 2005;54(1):103.
BACKGROUND: Colorectal cancers (CRCs) may be categorised according to the degree of microsatellite instability (MSI) exhibited, as MSI-high (MSI-H), MSI-low (MSI-L), or microsatellite stable (MSS). MSI-H status confers a survival advantage to patients with sporadic CRC.
AIMS: To determine if low levels of MSI are related to the clinicopathological features and prognosis of sporadic stage C CRC.
PATIENTS: A total of 255 patients who underwent resection for sporadic stage C CRC were studied. No patient received chemotherapy. Minimum follow up was five years.
METHODS: DNA extracted from archival malignant and non-malignant tissue was amplified by polymerase chain reaction using a panel of 11 microsatellites. MSI-H was defined as instability at>or =40% of markers, MSS as no instability, and MSI-L as instability at>0% but<40% of markers. Patients with MSI-H CRC were excluded from analysis as they have previously been shown to have better survival.
RESULTS: Thirty three MSI-L and 176 MSS CRCs were identified. There was no difference in biological characteristics or overall survival of MSI-L compared with MSS CRC but MSI-L was associated with poorer cancer specific survival (hazard ratio 2.0 (95% confidence interval 1.1-3.6)).
CONCLUSIONS: Sporadic MSI-L and MSS CRCs have comparable clinicopathological features. Further studies are required to assess the impact of MSI-L on prognosis.
Conjoint Gastroenterology, Laboratory, Royal Brisbane Hospital Research Foundation Clinical Research Center, Brisbane, Australia. carolinewright@hn.ozemail.com.au