Citations

401 Background: Pancreatic neuroendocrine tumors (PNETs) are rare neoplasms comprising less than 2% of pancreatic tumors. Outcomes of PNETs vary by stage, grade, and clinical presentation. New therapies may have improved outcomes. We present an analysis of the epidemiology and prognosis of patients (pts) with PNETs evaluating a more recent period than previously reported. Methods: Using data from the SEER registry, we identified adults with PNETs between 2000 and 2013. Cases were identified using a combination of ICD-O-3 site and histology codes. The JMP and SEER*STAT 8.3.2 were used for statistical analysis. Overall survival (OS) was analyzed using the Kaplan–Meier method. The prognostic effect of variables was studied using multivariate Cox proportional hazards models. Results: We identified 5993 pts with PNETs. Over the study duration, there was an increase in the annual incidence from 0.3 to 1.2 per 100.000. This was largely explained by the increase in number of pts with localized disease. The OS for the entire cohort was 54 months (95%; CI 50-58) and 5-year OS rates in localized, locally advanced and metastatic disease were 81.7%, 62% and 26% respectively. New therapies were increasingly implemented after 2008 such as sunitinib, everolimus and capecitabine/temozolomide. OS was better for pts diagnosed after 2008 (HR 0.73; 95% CI, 0.69-0.79; P < 0.0001) and this remained significant after excluding pts with localized disease (HR 0.85; 95% CI, 0.78-0.92; P = 0.0002). Factors found to favorably affect OS included younger age, female sex, early stage, low grade, and surgery. In metastatic disease, pts who had surgery had better OS and this was significant after adjusting for possible confounders (HR 0.36; 95% CI, 0.3-0.45). Conclusions: In this large population-based study, we saw an increase in the annual incidence of PNETs mainly due to an increased number of pts with localized disease. The OS has improved over the study duration likely due to both stage migration and new therapies used in advanced disease. Younger age, female gender, low histologic grade, early stage and surgery were found to be factors that favorably affected survival. Surgery was found to be a predictor of better outcomes in metastatic disease.

179 Background: GISTs arise from interstitial cells of Cajal anywhere within the gastrointestinal tract, but those of the esophagus and GEJ are exceedingly rare ( < 1% of cases). Our aim was to characterize clinicopathological features and outcomes of esophageal and GEJ GISTs and compare survival with a population-based registry (SEER). Methods: 28 cases were identified using the Mayo Clinic Cancer Registry from 1997 to 2016, and 378 cases from the SEER 18 registry from 2000 to 2013. Mayo cases were re-reviewed by Mayo pathologists. We analyzed patient characteristics, tumor location, TNM staging, mitotic index, molecular diagnostics, IHC staining, and histomorphology. JMP software was used to calculate time to recurrence (TTR) and overall survival (OS) utilizing Kaplan-Meier and log-rank. Results: At Mayo, 60% of tumors arose in the distal esophagus. Mean tumor size was 5.73 cm. 42% of cases were low grade. None had nodal involvement. Five cases were metastatic at diagnosis, all to the liver. 86.7% had spindle cell morphology. IHC staining was positive for KIT in 92%, followed by CD34 (52%), DOG-1 (24%), and actin (16%). Mutational analysis was done on 10 cases and KIT mutation was found in 8 cases; 2 were wild-type. Two-thirds of patients underwent surgery, mostly esophagectomy. 14 patients received adjuvant imatinib. Median time to diagnosis from symptom onset was 2 months; median time to surgery from diagnosis was 1 month. Of 10 patients with complete follow-up, 2 had recurrences: 1at the anastomotic site and 1 in the liver. Median TTR from surgery was 36.5 months. Median follow-up time was 31.5 months. Median OS from diagnosis for the Mayo cohort was 129.5 months (95% CI 55.7-x). SEER cohort median OS was 81 months (95% CI 63-101), and females had superior OS compared to males (HR 0.67; 95% CI 0.48-0.93, p = 0.016). Conclusions: Patients undergoing surgical resection for esophageal and GEJ GISTs had a favorable prognosis, but recurrences occurred. The superior OS seen in the Mayo cohort suggests early resection and adjuvant imatinib may improve outcomes.

584 Background: Standard therapy for stage II/III rectal cancer includes surgery, radiation, and chemotherapy. Multiple trials demonstrated neoadjuvant chemoradiation (CRT) provides better local control and decreased morbidity compared to adjuvant CRT, though differences in overall survival and long-term QoL have not been demonstrated. We examined impact of treatment (pre-op CRT/post-op CRT/no CRT) on long-term QoL. Methods: CanCORS patients with survey/medical record data diagnosed in 2003-2005 with stage II/III rectal (non-rectosigmoid) cancer had resection and survived > 7 years were included. QoL (SF-36, EQ-5D) measures and defecation problems were derived from surveys at 14 months and 7 years post-diagnosis. Mean scores were adjusted for the following when significant: age, gender, stage, sphincter preservation, comorbidities, and baseline self-reported health status and QoL scores. Results: Of 119 patients, 53% received pre-op CRT, 23% post-op CRT, and 24% no CRT. Of 114 patients with 14-month follow-up, Pre-op CRT and No CRT groups had better EQ-5D adjusted mean scores but worse defecation scale (DS) scores compared to the Post-op CRT group. Of 49 disease-free survivors with 7 years follow-up, there were no differences among groups in QoL scores, but the No CRT group had better DS scores than other groups. Conclusions: No major differences were detected in long-term QoL based on treatment aside from the DS, though sample sizes became small. Regardless of treatment, long term (7y) mental health and vitality were generally comparable to U.S. norms, while physical health and overall health status (EQ-5D) were somewhat lower. [Table: see text]

603 Background: Anal squamous cell carcinoma (Anal SCC) is a rare, HPV-associated malignancy accounting for 2.4% of digestive system cancers. In most cases, these malignancies are detected in the early stages and successfully managed with chemoradiation therapy. Uncommonly, these cancers recur or present with metastases. In this setting, cisplatin and 5-fluorouracil represent the only endorsed regimen. Once beyond standard therapy, few therapeutic options exist for those patients with aggressive disease. The purpose of this study is to identify other novel, potential targets and therapeutic options for this disease, utilizing a multiplatform approach. Methods: 206 anal SCC specimenswere tested via a multiplatform profiling service (Caris Life Sciences, Phoenix, AZ) consisting of gene sequencing (Sanger or next generation sequencing [NGS]), protein expression (immunohistochemistry [IHC]) and gene amplification (CISH or FISH). 6 cases were documented as positive for HPV or HIV; status was not provided on the remaining 200. Results: Key results are shown in the table below, shown as percent change/total cases. Conclusions: Multiplatform tumor profiling identified a low incidence of gene mutations. Protein expression aberrations identified potential treatment options not routinely considered, such as topoisomerase inhibitors and taxanes. Mutations in PIK3CA, Akt1, and FBXW7 as well as PTEN loss indicate potential for targeting the PI3 kinase pathway. Additionally, immunomodulatory agents may be a therapeutic option, based on PD-1 expression levels. Targeting the ErbB-family receptors, namely with anti-EGFR agents or newer generation pan-HER - inhibitors, may represent another option, given EGFR and HER2 amplification as well as EGFR overexpression. It should be mentioned that differences in anal carcinomas whose etiology is of viral origin may present different treatment options based on the driver mutations. [Table: see text]

710 Background: Leptomeningeal metastasis (LM) has been described as a rare form of metastatic disease progression in colorectal cancer (CRC). There remains a paucity of literature with regards to the course and management of LM in CRC. The aim of this study was to estimate the incidence of LM in CRC patients seen at our institution over a 15-year period, and to describe the clinical course and outcome of these cases. Methods: LM in CRC primary cases between 2000 and 2014 were identified in the Mayo Clinic databases. The charts were retrospectively reviewed. Results: Of 17,095 CRC primaries, we identified 10 patients with LM (0.058%) in this 15-year period. Nine cases were included in the analysis. Four had metastatic disease at the time of their initial CRC diagnosis. One patient also had a lung adenocarcinoma diagnosed during initial staging for the CRC primary. Median overall survival after CRC diagnosis was 25.7 months (range 4.7-74.8). Median time to diagnosis of LM after CRC diagnosis was 25.3 months (range 1-68.1). All patients had MRI findings consistent with LM: 3 patients with spinal LM, 5 patients with intracranial LM, 1 with both. One of three CSF analyses at the time of LM workup was positive for malignant cells; all had elevated protein. Neurologic symptoms correlated with site of the lesions, with headache, cranial nerve palsy, lower extremity weakness, and gait disturbance among the most frequently reported. However, not all patients had neurologic findings, with LM lesions found incidentally in two cases. Seven patients (78%) had palliative radiotherapy (RT) for LM. Three patients continued to receive systemic chemotherapy after diagnosis of LM. No patients underwent intrathecal chemotherapy. Median survival after LM diagnosis was 7 weeks (range 2-39). Conclusions: The diagnosis of LM is an exceedingly rare development in the natural course of CRC. It continues to confer an extremely poor prognosis with limited treatment options. At our institution, most patients had their disease addressed by palliative means, with many receiving RT to control their neurologic symptoms. Based on our series, supportive care remains a sensible approach to the management of LM in CRC.

569 Background: BBI-608 is an oral first-in-class cancer stemness inhibitor that blocks STAT3-mediated transcription of cancer stemness genes. Potent anti-CSC activity was observed in vitro and in vivo,in mono and combination therapy. In phase I studies, BBI-608 was generally well tolerated with encouraging signs of anti-tumor activity. Methods: A phase Ib open label, multi-center study in pts with advanced CRC was undertaken to confirm the RP2D of BBI-608 in combination with FOLFIRI with or without BEV. BBI-608 was administered at 240 mg BID in combination with FOLFIRI (5-FU 400 mg/m2 bolus with 2400 mg/m2, irinotecan 180 mg/m2, and leucovorin 400 mg/m2infusion) with or without BEV 5 mg/kg, administered bi-weekly until progression of disease, unacceptable toxicity, or other discontinuation criterion was met. Results: 18 heavily pretreated pts with an average of > 3 prior lines of therapy of which 10 pts (56%) previously progressed on FOLFIRI were enrolled. Of the 17 pts evaluable for response, 8 pts received FOLFIRI and 9 pts received FOLFIRI with BEV in combination with BBI-608. Most common adverse events included grade 1 and 2 diarrhea, abdominal pain, nausea, vomiting and anorexia. No dose limiting toxicity or new adverse events were seen, and the safety profile was similar to that of each regimen as monotherapy. Grade 3 events related to protocol therapy included diarrhea occurring in 3 pts, fatigue in 2 pts and dehydration in 1 pt. All events resolved after dose reduction and/or start of anti-diarrheal medications. No significant pharmacokinetic interactions were observed. Disease control (PR+SD) was observed in 16 of 17 evaluable pts (94%) with 2 PR (per RECIST 1.1 criteria: 44% and 33% regression) and 14 SD (of which 13 (93%) had tumor regression < 25%). In the evaluable pts, median progression free survival was 5.54 months. Of 17 pts, 7 (41%) had prolonged SD of > 6 months. Conclusions: This phase Ib study confirmed that BBI-608 at 240 mg bid can be safely combined with FOLFIRI with and without BEV, and shows encouraging anti-tumor activity in heavily pretreated CRC pts, even in pts with prior progression on FOLFIRI-based therapy. Clinical trial information: NCT02024607.

Extramammary Paget disease (EMPD) is a rare cutaneous malignancy. The most common presentation of EMPD is the vulva followed by perianal involvement. Most cases are localized to the dermis with treatment focused on surgery, topical treatment or radiotherapy. Recurrence is frequent despite therapies utilized. Metastatic extramammary Paget disease is uncommon and, as such, standard treatment guidelines do not exist. This study sought to evaluate the treatment regimens and outcomes of patients treated at a Mayo Clinic Center from 1998-2012. Cancer registry inquiry revealed 261 patients with report advanced Paget disease during these years. Ten cases of metastatic EPMD were identified with sufficient documentation for review. This review reveals support for utilizing localized radiation therapy for bulky disease sequentially with systemic chemotherapy consisting of carboplatin and paclitaxel or irinotecan. Further studies are necessary to define the optimal treatment regimen.

Neoadjuvant treatment may result in better quality of life and functional status 1 year after diagnosis.