Abstract 894P
Background
Accurate assessment of Ki67 is a key point in the diagnostic work-up of gastroentero-pancreatic neuroendocrine neoplasms (GEP-NENs) before planning a tailored treatment, owing to its prognostic role. However, there are concerns regarding the lack of uniformity for quantifying Ki67, particularly in low-volume centers with no specific expertise on NENs.
Methods
The aim of the study was to analyze the impact of histopathological revision on clinical management in patients with GEP-NENs.
All consecutive patients referred to the Sant’Andrea University Hospital ENETS-Center of Excellence of Rome between January 2015 and December 2021 were retrospectively included. Immunohistochemical slides at time of initial NEN diagnosis were obtained from paraffin-embebbed tissue blocks and reviewed to assess tumor morphology, diagnostic immunohistochemistry, and Ki67.
Results
A total of 101 patients were evaluated, including 65 (64.4%) gastrointestinal, 25 (24.7%) pancreatic, and 11 (10.9%) occult suspected to be of GEP origin. The reasons of a histological revision were assessment of new diagnoses made in centers with low experience in NEN (28.7%), grading confirmation before therapeutic choice (51.5%), and lack of grading/Ki-67 assessment (19.8%). Main histopathological changes resulting from the revision were: modification of Ki-67 in 48 (47.5%) and grading change in 20 (19.8%) pts. Overall, 78 (77.2%) patients needed an additional immunohistochemical staining particularly including CDX2, CK, TTF-1 and NSE.
According to the additional markers performed, an exclusion of NEN diagnosis was made in 2 (2%) pts and the GEP origin was confirmed in 10 (90.9%) of the 11 pts with unknown primary tumor site at initial diagnosis. After histopathological revision a new therapeutic indication was proposed in 42 (41.6%) pts. At Logistic regression, a clinical impact of histopathological revision was more frequently observed in stage II NEN (OR 5.83; P=0.005).
Conclusions
Histopathological revision in a referral NEN centerby an expert pathologist is advised in newly diagnosed GEP- NENs to properly plan prognostic stratification and therapeutic choice.
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.