RATES OF NODAL UNDER STAGING IN PANCREATIC DUCTAL ADENOCARCINOMA: FUEL FOR NEOADJUVANT CHEMOTHERAPY
Spencer Van Decar*, Alexandra Adams, Katryna K. Thomas, Todd Smolinsky, Elizabeth L. Carpenter, Guy Clifton, Timothy J. Vreeland
General Surgery, Brooke Army Medical Center, Fort Sam Houston, TX
Introduction:
Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease with poor prognosis. Neoadjuvant chemotherapy (NAT) for borderline disease yields improved outcomes. In addition to the vascular anatomic definition of borderline, a prior group identified that patients with clinical findings suspicious, but not diagnostic, for extrapancreatic disease have markedly worse outcomes indicating the importance of this additional category and the need for different treatment strategies. We sought to assess the rate of clinical nodal under staging in PDAC, as this group of patients with extra pancreatic disease may benefit from NAT versus surgery first given the importance of definitively receiving systemic therapy to benefit survival.
Methods:
The National Cancer Database 2019 Participant User File was queried for patients with clinically N0 (node negative), T stage 1-4 pancreatic adenocarcinoma who underwent R0/R1 pancreaticoduodenectomy with a surgery-first sequence (no neoadjuvant chemoradiation). We evaluated rates of pathologic nodal upstaging amongst all clinically node negative patients and evaluated T stage subgroups. Demographic and clinicopathologic information between patients who upstaged versus those who remained pathologically node negative were analyzed with Chi-Squared Tests. Binary multivariable logistic regression was performed to evaluate predictors of nodal upstaging.
Results:
17,560 clinically node negative patients from 2006 – 2019 who underwent surgery first sequence were evaluated. Overall, 57.7% (10125/17560) were nodally under staged. By subgroups, under staging occurred in 53.3% (2062/3871) of clinical (c) T1N0 patients, 62.3% (5237/8415) of cT2NO patients, 54.1% (2678/4950) of cT3N0 patients, and 43.0% (138/321) of cT4N0 patients. Comparing upstaged patients versus patients who remained node negative, T stage composition differed, with 51.8% of all upstaged patients being cT2 versus 42.7% of patients without nodal status change (p < .001). Insurance status (uninsured), Age < 65 and T stage, in particular T2, predicted upstaging (p = .007, p < .001, p < .001).
Conclusions:
Preoperative clinical evaluation of extrapancreatic nodal involvement in PDAC, similar to preoperative evaluation of tumor vascular contact, is difficult. Occult nodal disease is present in more than half of cN0 patients, even in early stage patients where a surgery first sequence remains the predominant treatment pathway. This further supports a NAT strategy for all patients with PDAC, as the majority of patients with PDAC are at high risk of nodal metastases, regardless of clinical staging.
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