Recurrence Patterns After Surgical Resection of Gastroenteropancreatic Neuroendocrine Tumors: Analysis From the National Comprehensive Cancer Network Oncology Outcomes Database

Gastroenteropancreatic Neuroendocrine Tumor Diagnosis: DOTATATE PET/CT

Gastroenteropancreatic neuroendocrine tumors(NETs), which arise from the small intestine, rectum, colon, appendix, or pancreas, have variable malignant potential with clinical behavior determined by proliferative activity according to the Ki-67 index and tumor differentiation. Somatostatin receptor (SSTR) expression by NETs allows SSTR imaging using 68Ga-DOTATATE PET/computed tomography (CT) and treatment with octreotide or SSTR-targeted peptide receptor radionuclide therapy (PRRT). 68Ga-DOTATATE PET/CT is indicated for localization of the primary tumor in select cases, staging patients with known NET, and selecting patients for PRRT. NCCN guidelines consider imaging with 68Ga-DOTATATE PET/CT appropriate for staging and receptor status assessment.

Association between surveillance imaging and survival outcomes in small bowel neuroendocrine tumors

BACKGROUND

Surveillance guidelines following the resection of small bowel neuroendocrine tumors (SB-NETs) are inconsistent. We evaluated the impact of surveillance imaging on SB-NET recurrence and overall survival (OS).

METHODS

Patients with completely resected SB-NETs referred to a provincial cancer center (2004-2015) were reviewed. Associations between imaging frequency, recurrence, post-recurrence treatment, and OS were determined using univariate and Cox-regression analyses.

RESULTS

Among 195 completely resected SB-NET patients, 31% were ≥70 years, 43% were female, and 80% had grade 1 disease. Imaging frequency was predictive of recurrence (hazard ratio 2.52, 95% confidence interval 1.84-3.46, p < 0.001). 72% underwent interventions for recurrent disease. Patients who were treated for the recurrent disease had comparable OS to those who did not recur (median 152 vs. 164 months; p = 0.25). Imaging frequency was not associated with OS in those with treated recurrent disease (p = 0.65). Patients who recurred underwent more computerized tomography (CT) scans than those who did not recur (CT: 1.47 ± 0.89 vs. 1.02 ± 0.81 scans/year, p < 0.001). Detection of disease recurrence was 5%-7% per year during the first 6 years of surveillance and peaked at 17% in Year 9.

CONCLUSION

Less frequent imaging over a longer duration should be emphasized to capture clinically relevant recurrences that can be treated to improve OS.

Surgical Treatment of Patients with Poorly Differentiated Pancreatic Neuroendocrine Carcinoma: An NCDB Analysis

BACKGROUND

Consensus guidelines discourage resection of poorly differentiated pancreatic neuroendocrine carcinoma (panNEC) given its association with poor long-term survival. This study assessed treatment patterns and outcomes for this rare malignancy using the National Cancer Database (NCDB).

METHODS

Patients with non-functional pancreatic neuroendocrine tumors in the NCDB (2004-2016) were categorized based on pathologic differentiation. Logistic and Cox proportional hazard regressions identified associations with resection and overall survival (OS). Survival was compared using Kaplan-Meier and log-rank tests.

RESULTS

Most patients (83%) in the cohort of 8560 patients had well-differentiated tumors (panNET). The median OS was 47 months (panNET, 63 months vs panNEC, 17 months; p < 0.001). Surgery was less likely for older patients (odds ratio [OR], 0.97), patients with panNEC (OR, 0.27), and patients with metastasis at diagnosis (OR, 0.08) (all p < 0.001). After propensity score-matching of these factors, surgical resection was associated with longer OS (82 vs 29 months; p < 0.001) and a decreased hazard of mortality (hazard ratio [HR], 0.37; p < 0.001). Surgery remained associated with longer OS when stratified by differentiation (98 vs 41 months for patients with panNET and 36 vs 8 months for patients with panNEC). Overall survival did not differ between patients with panNEC who underwent surgery and patients with panNET who did not (both 39 months; p = 0.294).

CONCLUSIONS

Poorly differentiated panNEC exhibits poorer survival than well-differentiated panNET. In the current cohort, surgical resection was strongly and independently associated with improved OS, suggesting that patients with panNEC who are suitable operative candidates should be considered for multimodality therapy, including surgery.