The differential effect of neoadjuvant chemotherapy and chemoradiation on nodal downstaging in pancreatic adenocarcinoma.

BACKGROUND/OBJECTIVES: Neoadjuvant chemotherapy (NCT) and chemoradiotherapy (NCRT) enhance resectability in patients with pancreatic adenocarcinoma (PDAC). This study compares the effect of NCT and NCRT on lymph nodal downstaging and survival. METHODS: The 2004-2016 National Cancer Database Pancreas Participant User File was used to identify patients who underwent surgery for PDAC. Fisher's exact, Wilcoxon rank-sum, multivariate logistic regression, and log-rank were used. Downstaging was defined as clinically node-positive patients who demonstrated node-negativity on pathology. RESULTS: Of 42,545 patients meeting criteria, 3311 received NCT and 1511 received NCRT. After surgery for clinically node-positive disease, 23.3% of NCT patients and 41.3% of NCRT patients demonstrated nodal downstaging. Younger age and lower tumor grade independently predicted downstaging. Downstaging after neoadjuvant therapy was associated with improved survival versus no nodal treatment response (29.8 vs. 22.8 months, p < 0.001). Downstaging by NCT was associated with improved overall survival versus downstaging by NCRT (37.5 vs. 26.6 months, p = 0.001). No survival difference existed between those with no nodal response after NCT or NCRT (p = 0.101). CONCLUSIONS: Although nodal downstaging is more likely post-NCRT, survival is superior in those downstaged post-NCT. Overall survival is determined by the systemic burden of disease. Post-therapy histologic analysis may be less prognostic post-NCRT.

The role of oncologic resection and enucleation for small pancreatic neuroendocrine tumors.

BACKGROUND: Surgical management of small pancreatic neuroendocrine tumors (PNETs) is variable. Patients may undergo formal oncologic resection, encompassing regional lymphadenectomy, or enucleation. This study's aim was to understand if enucleation is adequate treatment for PNETs <2 cm METHODS: The US National Cancer Database (NCDB) from 2004 to 2016 was used to identify patients who underwent oncologic resection or enucleation for PNETs <2 cm. Fisher's exact test, log-rank, and logistic regression were used. RESULTS: Of 4083 patients, 75.6% underwent oncologic resection with a median (range) number of 8 (0-99) lymph nodes examined, and 24.1% underwent enucleation. Five-year overall survival rate was 89.7% in node-negative patients versus 82.1% in node-positive patients (p < 0.001). No survival difference existed between patients who underwent enucleation versus oncologic resection (5-yr OS of 88.5% vs 88.2%, p = 0.064). According to AJCC classification, 3776 patients were clinically-staged with evidence of node-negative disease. Of these, 75.1% underwent oncologic resection, of which 9.9% had node-positive disease after resection. Tumor grade and size independently predicted nodal upstaging after oncologic resection. CONCLUSION: One-tenth of patients with clinically node-negative disease were node-positive after surgery. Although this was not reflected in overall survival, patients who receive enucleation with higher grade and larger size may benefit from enhanced surveillance for locoregional recurrence.