Molecular genetic alterations in endometrioid carcinomas of the ovary : similar frequency of beta-catenin abnormalities but lower rate of microsatellite instability and PTEN alterations than in uterine endometrioid carcinomas .
Endometrioid carcinomas of the ovary closely resemble their uterine counterparts .
It has been suggested that the former tumors have the same molecular alterations ( microsatellite instability [ MSI ] , PTEN , and beta-catenin ) described in endometrioid carcinomas of the uterus .
We analyzed 55 ovarian carcinomas , including 22 endometrioid , 18 clear cell , and 15 mixed types .
MSI was detected in 5 of 39 cases ( 13 % ) .
MLH1 promoter hypermethylation was identified in 2 of the 5 MSI-positive tumors .
PTEN was mutated in 5 of 54 cases ( 9 % ) ; of these , 3 had MSI and exhibited frameshift mutations in short-coding mononucleotide repeats .
Beta-catenin nuclear expression was detected in 11 of 54 cases ( 20 % ) by immunostaining ; of these , 7 exhibited CTNNB1 gene mutations .
These alterations were found more frequently in endometrioid carcinomas than in tumors of the other 2 groups .
Among the former tumors , MSI was detected in 3 of 17 cases ( 17.5 % ) ; PTEN mutations , in 3 of 21 ( 14 % ) ; and beta-catenin , in 8 of 21 ( 38 % ) .
The molecular alterations were found more often in tumors associated with endometriosis than in tumors without endometriosis .
Six endometrioid tumors demonstrating matrix metalloproteinase-7 ( MMP-7 ) immunoreactivity with nuclear accumulation of beta-catenin had good outcomes , in contrast to poor outcomes in 7 of 9 predominantly nonendometrioid tumors demonstrating expression of MMP-7 only .
We found a similar frequency of beta-catenin abnormalities but lower rates of MSI and PTEN alterations than in uterine endometrioid carcinomas .
Alterations in beta-catenin and PTEN genes , as well as MSI , are frequent in low-stage ovarian carcinomas of endometrioid type that have a favorable prognosis .