1191P - TTF-1 expression in lung neuroendocrine tumors (NET): A gender-related biomarker

Background

Thyroid transcription factor-1 (TTF-1), is expressed in thyroid and lung tissue. TTF-1, assessed by immunohistochemistry (IHC), is a specific biomarker for lung adenocarcinoma, and is commonly used to confirm the pulmonary origin of neuroendocrine tumors (NET), as well. The majority of the available data suggest that TTF-1 is a favourable prognostic biomarker for lung adenocarcinomas, whereas its role in lung NET is controversial.

Methods

A multicenter retrospective study, including 155 Lung NET, all surgically removed, all with available IHC assessment for TTF-1.

Results

Median age was 59.5 years (13–86), N= 58 patients (37.4%) were males, N=40 (25.8%) were smokers, N=31 (20%) were atypical carcinoids, N=85 (54.8%) were centrally-located, N=89 (57.4%) were located in the right lung, N=4 patients (2.6%) presented a TNM stage IV at the diagnosis. Mitotic count was ≥2 per 10 high-power field (HPF) in N=35 cases (22.6%), necrosis was present in N=20 (12.9%). Grade 1 was reported in 103 cases (66.5%), whereas Ki-67 was >20% in N=5 (3.2%). TTF-1 was positive in 78 cases (50.3%), cromogranin A in 139 (89.7%) and synaptophysin in 137 (88.4%), respectively. The most common type of surgery was lobectomy in 91 patients (58.7%). Median overall survival (OS) was 46.9 months (0.6–323), median progression-free survival (PFS) was 39.1 months (0.6–323). Statistically significant associations were found between (i) TTF-1 positivity and female sex (p=0.007), and among (ii) TTF-1 positivity and the absence of necrosis (p=0.018). No other relevant associations were detected between TTF-1 and the remaining clinical or pathological variables.

Conclusions

This study highlights that TTF-1 positivity differs according to sex in lung NET patients, with a more common TTF-1 positive staining in female. Moreover, TTF-1 was associated with the absence of necrosis. These data suggest that TTF-1 could potentially represent a gender-related biomarker in this population. Further analyses are needed to establish the value of this observation, and to determine the value of TTF-1 as prognostic biomarker for lung NET.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.