A. J. Lee1, Y. Chiang1, C. Conrad1, Y. Chun-Segraves1, J. Lee1, T. Aloia1, J. Vauthey1, C. Tzeng1 1University Of Texas MD Anderson Cancer Center,Surgical Oncology,Houston, TX, USA
Introduction: For gallbladder cancer (GBC), the new American Joint Committee on Cancer 8th edition (AJCC8) staging system classifies lymph node (LN) stage by the number of metastatic LN, rather than their anatomic location as in AJCC6 and AJCC7. Additionally, AJCC8 now recommends resection of ≥6 LNs for adequate nodal staging. In the context of this new staging system and recommendation for GBC surgery, we evaluated current national trends in LN staging and sought to identify factors associated with any and/or adequate LN staging according to this new guideline.
Methods: Utilizing the National Cancer Data Base (NCDB), we identified all gallbladder adenocarcinoma patients treated with surgical resection with complete tumor staging information between 2004-2014. We excluded patients with T1a and lower pathologic T-stage, as nodal staging is not indicated in these patients. Nodal staging and nodal positivity rates were compared over the study period. Univariate and multivariate logistic regression modeling were performed to identify factors associated with any and/or adequate nodal staging.
Results: We identified 11,525 patients with T-stage ≥T1b, for whom lymphadenectomy is recommended. Only 49.6% (n=5,719) of patients had any LN removed for staging. On multivariate analysis, treatment at academic centers (OR=2.33, p<0.001), more recent year of diagnosis (OR=2.29, p<0.001), clinical node-positive status (OR=3.46, p<0.001), pathologic T2 stage (OR=1.25, p<0.001), and radical surgical resection (OR=4.85, p<0.001) were associated with higher likelihood of having any nodal staging. Age ≥80 (OR=0.57, p <0.001), and higher co-morbidity index (OR=0.70, p<0.001) were associated with lower likelihood of having any nodal staging. However, of the 5,719 patients who underwent any nodal staging, only 21.8% (n=1,244) met the AJCC8 recommendation of adequate LN staging. On multivariate analysis, female sex (OR=1.18, p=0.02), treatment at academic centers (OR=1.52, p<0.001), radical surgical resection (OR=2.53, p<0.001), and pathologic T4 stage (OR=2.14, p<0.001) were associated with having ≥6 LN resected concomitantly with their oncologic operation. Patients over 80 years old (OR=0.60, p<0.001) and in South region (OR=0.79, p=0.002) were less likely to have adequate LN sampling according to the new recommendation.
Conclusion: National trends in the overall GBC LN staging rate of 49.6% do not live up to the new AJCC8 recommendations. Furthermore, the finding that only 21.8% of patients met the 6 LN threshold highlights the gap between the new AJCC8 recommendations and reality. We have identified demographic and clinicopathologic factors associated with any and/or adequate LN staging, which can be incorporated into future targeted quality improvement initiatives.