REEXAMINING 8TH EDITION OF AMERICAN JOINT COMMITTEE ON CANCER NODAL STAGING AMONG PATIENTS WITH PANCREATIC CANCER FOLLOWING NEOADJUVANT THERAPY
Mohammed Aldakkak*, Saryn Doucette, Bryan Hunt, Chiang-Ching Huang, Sam Thalji, Kathleen Christians, Callisia N. Clarke, Mandana Kamgar, Ben George, Beth A. Erickson, William Hall, Douglas B. B. Evans, Susan Tsai
Medical College of Wisconsin, Milwaukee, WI
Introduction: American Joint Committee on Cancer staging (AJCC 8th Ed.) system classifies pancreatic cancers (PC) into three lymph node (LN) stages. We evaluated the association of number of positive LN and survival following neoadjuvant therapy (NeoTx).
Methods: Patients with PC who received NeoTx and surgery were identified from the National Cancer Database (NCDB). Patients with metastatic disease or patients with no LN examined were excluded. Median overall survival (mOS) was compared by number of positive LNs (LN+). AJCC 8th Ed. and alternative nodal staging classification were compared using net reclassification improvement (NRI) analysis.
Results: Of the 6,039 patients identified, NeoTx consisted of chemotherapy alone in 3,883 (64%), radiation in 52 (1%), and both in 2,104 (35%). Of the 6,039 patients, 3,097 (51%) were node negative (N0), 991 (16%) had 1 LN+, 598 (10%) had 2 LN+, 411 (7%) had 3 LN+, and 942 (16%) had >= 4 LN+. Median examined regional lymph nodes was 17 (IQR:12). mOS was 37, 29, 29, 23, 21 months (mo) among patients with N0, 1LN+, 2LN+, 3LN+, >=4LN+. mOS was similar between patients with 1 vs. 2 LN+ (p=0.74) but was 6 mo shorter in patients with 3 LN+ (1 vs. 3 LN+, p=0.0001; 2 vs. 3 LN+, p=0.0007). Additionally, mOS in patients with 3 LN+ was not different from >=4 LN+ (p=0.08). Using AJCC 8th Ed. classification, mOS was 37, 28, and 21 mo for N0, N1 (1-3 LN+), and N2 (>=4 LN+) disease, respectively (p<0.0001). Using an alternative classification of N0*, N1* (1-2LN+), and N2* (>= 3LN+), the mOS was 37, 29, and 22 mo (p<0.0001). Classification systems were compared using NRI analysis and demonstrated a significant improvement at 60 mo for the alternative classification (3.76%, 95% CI [3.03% - 5.12%]).
Conclusions: Following NeoTx, patients with PC who have 3 LN+ experience a worse survival than patients with 1 or 2 LN+. This difference in mOS is not currently captured in the 8th Ed. of the AJCC staging system and may impact decision making regarding additional adjuvant therapy.
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