Abstract 1812P
Background
At the present time, TTF-1 seems to be the single best marker for adenocarcinoma. TTF-1 helps to confirm a primary lung origin in 75 to 85% of lung adenocarcinoma. But in the remaining lung adenocarcinoma patients (pts) TTF-1 is not expressed. Detailed clinical, pathological and molecular features about last mentioned subgroup of pts is lacking. Furthermore, enteric differentiation can occur in lung adenocarcinoma, and when this component exceeds 50%, the tumor is classified as pulmonary adenocarcinoma with enteric differentiation (PAED) and detailed characteristics of these pts are lacking too.
Methods
NSCLC pts who were diagnosed from January 2018 until April 2021 were identified by review of the patient records. Only lung adenocarcinoma pts whose tumors didn`t express TTF-1 and Napsin A were evaluated. Enteric adenocarcinomas were confirmed by expression of CDX-2, CK20 or MUC2 and these patients were included in the data analysis. Primary tumors of the gastrointestinal tract were excluded either by PET-CT and/or CT and endoscopy (gastroscopy, colonoscopy, and rectoscopy).
Results
A total of 53 pts (31 males (58.5%), 22 females (41.5%)) were found. On average, pts were 67 years old, the median age was 68 (range: 54-83 years) old. Out of whole cohort 24 pts were diagnosed in a local stage, 29 had metastatic disease (stage IV). Tumors with any PD-L1 expression were found in about 50 % of the pts. Median disease-free survival of 17 pts with surgical resection was 8 months, median progression-free survival of any stage IV pts (29) with firstline systemic treatment was 3 months. No difference between chemotherapy and chemo-/immunotherapy treatments were noticed (median PFS: 3 months (range: 0-12) vs. 3 months (range: 0-15). Furthermore, 15 pts suffered from PAED. Regarding molecular alterations in stage IV pts, a significant higher percentage of KRAS mutations was found in PAED pts (37 % vs. 24.5 %).
Conclusions
At present, this is the largest series of clinical and pathological features of lung adenocarcinoma pts without TTF1- and Napsin A expression and particularly with enteric differentiation.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Daniel Christoph.
Funding
Has not received any funding.
Disclosure
D.C. Christoph: Financial Interests, Invited Speaker: AstraZeneca; Financial Interests, Invited Speaker: Bayer; Financial Interests, Invited Speaker: Boehringer- Ingelheim; Financial Interests, Invited Speaker: Bristol- Myers Squibb; Financial Interests, Invited Speaker: Chugai; Financial Interests, Invited Speaker: MSD; Financial Interests, Invited Speaker: Novartis; Financial Interests, Invited Speaker: Pfizer; Financial Interests, Invited Speaker: Roche; Financial Interests, Invited Speaker: Sanofi, Financial Interests, Invited Speaker: Takeda. All other authors have declared no conflicts of interest.