High microsatellite instability occurs in about 15% of colorectal cancers.
Clinical as well as pathological features differ from tumors exhibiting low microsatellite instability or microsatellite stability.
Conflicting data exists about the relevance of microsatellite instability in predicting the prognosis of colorectal cancer.
There is also conflicting evidence about the benefit of 5-fluorouracil based chemotherapy in patients with colorectal cancer.
Dr Lamberti and colleagues from Germany investigated the usefulness of microsatellite instability as a predictor of distinct clinical attributes influencing recurrence rate.
The team also evaluated disease-free survival subject to the use of adjuvant or palliative chemotherapy with 5-fluorouracil in stage 2 to 4 of colorectal cancer.
The researchers collected data and tumours of 416 consecutive stage 1 to 4 in colorectal cancer patients from 2000 to 2002.
|Microsatellite stability tumors were identified in 82%|
|International Journal of Colorectal Diseases|
The team followed the patients for a median time of 33 months.
Microsatellite loci recommended by the National Cancer Institute were analyzed.
The researchers used cox proportional hazard modelling to compare clinical data and survival.
The team evaluated the associations for microsatellite instability and 5-fluorouracil treatment status with high microsatellite instability colorectal cancer.
The researchers assessed the associations of microsatellite instability and 5-fluorouracil with low microsatellite instability or stability in colorectal cancer.
The researchers identified high microsatellite instability in 13%, low microsatellite instability in 5%, and microsatellite stability tumors in 82%.
Colorectal cancer with high microsatellite instability tended to have a decreased likelihood of metastasising to regional lymph nodes.
However, the researchers noted that age of diagnosis and tumor location did not differ.
The team found no difference between high microsatellite instability and microsatellite stability groups regarding disease-free, and overall survival when chemotherapy was not taken into account.
Furthermore, survival under application of 5-fluorouracil did not correlate with microsatellite instability status.
Dr Lamberti's team concludes, “No clear influence of microsatellite instability status on overall survival and response to 5-fluorouracil chemotherapy was found.”