Endocrine Abstracts

Background: Grade 3 disease is considered difficult or impossible to eradicate in most patients with NENs. We sought to describe the pathways to long term treatment-free survival or apparent cure in a cohort of tertiary care patients.

Methods: A registry analysis identified NEN patients with 1) no imaging evidence of disease or 2) long-term nonprogressive disease without treatment, seen over the previous 23 years. Criteria included Ki-67 >20% or high-grade histology and no evidence of disease on no treatment for >5 years (stage I-III) or no evidence of disease progression or activity for at least 2 years (for stage IV disease).

Results: A total of 51 patients (60.8% male, 39.2% female) were eligible for analysis. Whites consisted of 88.2% and African Americans were 11.8%. Most tumors were original diagnoses and originated in the head and neck area (31.6%) followed by GI (29.8%) and GU (22.8%). Pathology was poorly differentiated in 54.9% and mixed in 25.5% of the cases. Patient staging on initial presentation was 1 (27.5%), 2 (21.6%), 3 (19.6%) and 4 (31.4%). Most common general treatments strategies included a combination of approaches (62.8%). Commonly used patterns were surgery and chemotherapy (32%) followed by chemotherapy and radiation (20%) and surgery as single treatment (14%). Most common first line treatments were curative surgery (62.7%) followed by localized radiation (21.6%), with only 7.8% of patients stopping treatment because of intolerance. Most second line treatments consisted of chemotherapy with platinum and etoposide (31.4%) with localized radiation (11.8%). Patients with metastatic disease on diagnosis were all treated with immunotherapy. Most patients underwent surgery followed by platinum chemotherapy. Only 5.9% of patients received a 4th and only 2% received a 6th treatment. Only 3.92% of patients were enrolled in a clinical trial. Currently 84.3% of patients have no evidence of disease while 3.9% have long term stable disease. Most patients (78.4%) are alive as of last follow-up. A logistic regression model showed that patients with poorly differentiated histology and GU/head and neck origins had a statistically significant higher risk of death.

Conclusions: The most common road to cure or long-term remission for patients with grade 3 disease consists of surgery with platinum chemotherapy or radiation. The only pathway for those with metastatic disease included immunotherapy. Origin and histology affects survival despite apparent disease eradication. More analyses are ongoing.

ABSTRACT ID28787