SUN-142 Clinical Characteristics of Patients Diagnosed with Functional Neuroendocrine Tumors Treated at a Tertiary National Referral Center in Mexico

Neuroendocrine tumors (NET) represent up to 0.5% of all new cancers and can be functional or non-functional. Epidemiologic data on NET in Mexico is very limited. To delineate the clinical characteristics of patients with functional NET at a tertiary national referral center in Mexico we performed a retrospective cohort study (January 1987-June 2019). The target study population was adults with functional NET with biochemical and histopathological confirmation. Results: 126 patients with functional NET were included in this study. The median follow-up was 47.4 months (IQR 10.8 to 93.7). Most were female (64.3%). The mean age at diagnosis was 46.3 ± 14.48 years. The most frequent insulinomas (59.5%), followed by (12.7%) carcinoid tumors, gastrinomas (11.1%), ACTHomas (10.3%), VIPomas (2.4%) glucagonomas (2.4%) and PPomas (1.6%). Nineteen subjects (15.1%) had genetic syndromes, mainly MEN1 (89.5%); and 8.7% had other neoplasms, most frequently non-functional gastrointestinal (GI) carcinoids (36.3%) and thyroid cancer (18.8%). The median duration of symptoms prior to diagnosis was 24 months (IQR 7.75 to 48). The most common locations were, the GI tract (86.5%), whereas 7.1% were outside the GI tract and 6.4% were of unknown primary origin. Functional NETs outside GI tract were localized primarily in lungs (66.6%). Functional pancreatic NETs occurred more commonly in the tail (39.6%). 24.6% had locoregional or distant metastasis during follow-up. The most frequent metastatic sites were liver (86.5%), regional lymph nodes (59.8%) and bone (13.5%). The most common treatment was surgery (87.3%, with 13.6% ≥2), followed by 18.3% somatostatin receptor analogues and 11.1% cytotoxic chemotherapy. Most subjects (73%) had complete remission with first line therapy, but 14.1% had recurrence at a median of 50.7 months (IQR 15.4 to 97.6). Subjects with an incomplete remission progressed after a median of 14.85 months (IQR 10 to 38.9). Conclusions: The clinical characteristics of functional NET treated at a tertiary center in Mexico are similar to those in other population and geographic locations described in the literature.