Distinct Indications for Adjuvant Therapy in Resected Invasive Mucinous Cystic Neoplasms of the Pancreas Compared with Pancreatic Ductal Adenocarcinoma.

ABSTRACT

BACKGROUND: Surgical and adjuvant management of mucinous cystic neoplasms (MCNs) lacks formal guidelines and data is limited to institutional studies. Factors associated with receipt of adjuvant therapy and any associated impact on survival remain to be clarified. In the absence of other data, guidelines that recommend adjuvant chemotherapy for invasive pancreatic adenocarcinoma have been extrapolated to MCN. PATIENTS AND METHODS: The National Cancer Database (2004-2019) was utilized to identify all patients that underwent pancreatic resection for invasive MCNs. Patients that received neoadjuvant therapy or did not undergo lymphadenectomy were excluded. Patient, tumor, and treatment factors associated with survival were assessed. RESULTS: For 161 patients with invasive MCN, median overall survival (OS) was 133 months and 45% of patients received adjuvant therapy. Multivariable analysis demonstrated that poorly differentiated tumors [odds ratio (OR) 4.19, 95% confidence interval (CI) 1.47-11.98; p = 0.008] and positive lymph node status (OR 2.67, 95% CI 1.02-6.98; p = 0.042) were independent predictors of receiving adjuvant therapy. Lymph node positivity [hazard ratio (HR) 2.90, 95% CI 1.47-5.73; p = 0.002], positive margins (HR 5.28, 95% CI 2.28-12.27; p < 0.001), and stage III disease (HR 12.46, 95% CI 1.40-111.05; p = 0.024) were associated with worse OS. Receipt of adjuvant systemic therapy was independently associated with decreased risk of mortality in node positive patients (HR 0.23, 95% CI 0.10-0.69; p = 0.002). Survival was not associated with adjuvant therapy in patients with negative lymph nodes or margin negative status. CONCLUSION: In contrast to pancreatic ductal adenocarcinoma (PDAC), where adjuvant therapy improves OS for every tumor stage, surgery alone for invasive MCN is not associated with improved OS compared with surgery plus adjuvant therapy in node-negative patients. Surgery alone is likely sufficient for a subset of invasive MCN.