Microsatellite instability in poorly differentiated adenocarcinomas of the colon and rectum: relationship to clinicopathological features.
BACKGROUND
Poorly differentiated adenocarcinomas of the colon and rectum (Por) feature the worst prognosis among the various types of colorectal carcinomas. Por is highly associated with microsatellite instability (MSI), although MSI is associated with an improved prognosis in colorectal cancers.


OBJECTIVE
To investigate the influence of MSI on clinicopathological features and survival of patients affected by Por.


METHODS
53 patients affected by Por were investigated. DNA extracted from tumour sections and the corresponding normal tissue was analysed by PCR at five microsatellite loci: BAT25, BAT26, D2S123, D5S346 and D17S250. Tumours with alterations at two or more loci were classified as MSI-Por. The others were classified as microsatellite stability (MSS)-Por. The clinicopathological features and survival of patients with MSI-Por and MSS-Por were investigated.


RESULTS
Of the 53 patients who were examined, 12 (22.6%) were MSI-Por, whereas 41 (77.4%) were MSS-Por. Significant differences were found between MSI-Por and MSS-Por regarding the following clinicopathological features: age, gender, lymph-node metastasis (MSI-Por: 4/12; MSS-Por: 33/41), TNM stage (MSI-Por: T1/T2/T3/T4 = 2/6/2/2; MSS-Por: 3/3/19/16) and lymphatic invasion (MSI-Por: 4/10; MSS-Por: 27/35). Kaplan-Meier survival curves and log-rank analysis showed that MSI-Por was associated with better prognosis than MSS-Por, although no significant difference was found.


CONCLUSIONS
Compared with MSS-Por, MSI-Por is significantly associated with a low incidence of lymph-node metastases and a low stage. This indicates that MSI-Por is a less aggressive subtype.
Kazama
Yoshihiro
Y
Department of Surgical Oncology, University of Tokyo, Tokyo, Japan.
Watanabe
Toshiaki
T
Kanazawa
Takamitsu
T
Tanaka
Junichiro
J
Tanaka
Toshiaki
T
Nagawa
Hirokazu
H
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology / Q000556:secondary; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D016019:Survival Analysis
D004273:DNA, Neoplasm