Thyroid transcription factor-1 (TTF-1) immunoreactivity is an adverse prognostic factor in endometrioid adenocarcinoma of the uterine corpus

Aims: It is known that thyroid transcription factor-1 (TTF-1) is expressed in a small percentage of primary gynaecological adenocarcinomas. Following the observation of TTF-1 positivity in a number of endometrioid adenocarcinomas of the uterine corpus which behaved aggressively, we undertook immunohistochemical staining of a large series of endometrial adenocarcinomas of various types to investigate whether its expression is of prognostic significance.

Methods and results: TTF-1 was performed on tissue microarrays containing 102 low-grade (grades 1 or 2) endometrioid adenocarcinomas, 101 grade 3 endometrioid adenocarcinomas, 89 serous adenocarcinomas and 29 clear cell carcinomas. All categories of endometrial adenocarcinoma exhibited TTF-1 staining in a small subset of cases (2% low-grade endometrioid, 11% grade 3 endometrioid, 9% serous, 7% clear cell). TTF-1 was less frequently expressed in low-grade endometrioid adenocarcinomas compared to other subtypes. Endometrioid adenocarcinomas which expressed TTF-1 had a statistically significant worse prognosis with poorer disease-specific survival, and this was also statistically significant in the group of low-grade endometrioid adenocarcinomas.

Conclusions: Our study confirms that TTF-1 is expressed in a small, but not insignificant, proportion of endometrial adenocarcinomas. TTF-1 positivity in low-grade endometrioid adenocarcinomas is an indicator of poorer prognosis.