Neuroendocrine neoplasm: A 10-year retrospective review of a single-center experience.

Abstract

e16349 Background: Neuroendocrine neoplasm (NENs) are uncommon, diverse tumors with different phenotypes & behaviors. This study aims to examine the diagnostic and treatment strategies used in Alexandria Main University Hospital oncology department. Methods: A total of 105 patients were observed over a 10 year period from Jan.2011 till Dec.2020, 22 were excluded due to missing data & 3 due to having 2 primaries. The remaining 80 patients were subdivided into 43 who were non metastatic NEN & 37 with metastatic NEN (mNENs). Patients were analyzed based on gender, age, grade, stage, primary tumor site, and treatment modality. Response rate for each line of treatment was assessed according to Recist criteria. DFS, PFS ,and OS were calculated with two sided p value < 0.05 was statistically significant. Results: 43 patients were non metastatic NENs 53.7 % and 37 were mNENs 46.2%. Almost Half of the patients were detected between 2018-2020 with a mean age of 51.5. Male incidence was slightly higher at 53.8%. Small intestinal NEN was the most common site at 38.6 %, followed by pancreatic 26.3 % and a notable number of unknown primary sites 7.5 %. Regarding mNENs, liver was the most common site 56.7% compared to other sites. G I & II neuroendocrine tumors (NET) were the most common in the whole cohort at 62.6% compared to G III NETs and Neuroendocrine carcinoma (NEC) at 10% & 17.5% respectively. While classifying NENs according to Ki 67 and mitotic index, 81.3 % were of unknown mitotic index and the grade was finalized on Ki 67. Unfortunately, this could be misleading as an unexpected poor outcome was related to some patients known to be low KI 67 which may have been justified if mitotic index had been done. Patients with measurable disease, 27 received Somatostatin analogues with a response rate 74% and median time to response 35 months. 40% of them maintained SD for a median time of 18 months. Only 5 were under wait & see approach, 3 maintained SD for a median time of 19 months. Mean OS of non metastatic patients was 115 months with 5 year OS 77.5 % which is much higher than mNETs with p = 0.003. Surgery was associated with OS benefit in both mNET and non-metastatic with p = 0.001 however, no OS nor DFS benefit according to nodal status with p = 0.5 and 0.3 respectively. Regardless of any other parameters, G I & II NET has best OS with p < 0.001 compared to G3 NETs and NEC while there was no difference in OS between G3 NETs and NEC with p = 0.35. In mNET no OS benefit according to treatment modality with p = 0.08 although there is PFS benefit with p = 0.01. Correlating the grade to treatment modality, no OS nor PFS noted in patients with well differentiated GI tumors who were under wait & see approach and who received hormonal treatment with p = 0.1. Conclusions: This retrospective study highlights the crucial significance of tumor grade as this factor is strongly associated with survival benefit and suitable tailoring of treatment. Additionally, the necessity of KI 67 & mitotic index for accurate grading.