BACKGROUND. The purpose of this study was to compare the clinical character
istics of endometrial carcinomas with and without microsatellite instabilit
y (MSI).
METHODS. The authors prospectively acquired DNA from patients with endometr
ial carcinomas at Washington University Medical Center. Tumors were assigne
d MSI (+) status when two or more of five microsatellite repeat markers rev
ealed novel bands in tumor DNA not present in the corresponding normal DNA.
Clinical characteristics and survival data of patients with and without MS
I were abstracted from patient charts. Statistical significance was calcula
ted with the chi-square test, and survival was assessed with Kaplan-Meier m
ethods.
RESULTS. The authors found 65 of 70 (93%) patients with MSI (+) tumors to b
e of white race, whereas only 124 of 159 (78%) patients with MSI (-) tumors
were white (P = 0.012). Advanced disease (International Federation of Gyne
cology and Obstetrics Stage III-nr) was observed in 9 of 70 (13%) MSI (+) p
atients and 44 of 159 (28%) MSI (-) patients (P = 0.017). In addition, aggr
essive histologic subtypes were observed less frequently in MSI (+) tumors
(6/70 [8%]) than in MSI (-) tumors (30 of 159 [19%]) (P = 0.034). Race and
stage were shown by multivariate analysis to be different in MSI (+) and MS
I (-) patients. Recurrence and overall survival were similar in the two gro
ups.
CONCLUSIONS, Patients with MSI (+) tumors were more likely to be of white r
ace and to present with early stage disease. Further investigation is neede
d to explain why patients with MSI (+) tumors have similar survival to pati
ents with MSI (-) tumors, despite presenting at earlier stages, being of wh
ite race, and being less likely to be associated with virulent histologic s
ubtypes. Cancer 2000;89:1758-64. (C) 2000 American Cancer Society.