P0027 - Squamous Cell Carcinoma of the Extrahepatic Bile Ducts: A National Cancer Database Analysis of a Rare Cholangiocarcinoma Histologic Variant

Jad Mitri, MD¹, Elena Panettieri, MD², Eduardo Vega, MD^2
1St. Elizabeth's Medical Center, Boston, MA; ²Saint Elizabeth's Medical Center, Boston, MA

Introduction: Squamous cell carcinoma (SCC) is a rare subtype of cholangiocarcinoma with limited previous literature. The aimed was to describe demographics, tumor characteristics, and survival outcomes in a cohort of 102 cases of SCC variant of extrahepatic cholangiocarcinoma (EHCC).

Methods: National Cancer Database was queried for patients with a diagnosis of EHCC, SCC and adenocarcinoma (AC) types between 2004-2018. Tumor primary site was determined through International Classification of Diseases 10 (ICD-10) codes C24.0-24.9.
Patient (age, race, sex, Charlson-Deyo comorbidity score), tumor (grade, tumor size, metastatic sites, therapeutic approach, margin positivity) and survival characteristics were analyzed and compared between SCC and AC. We used Chi-square and Mann-Whitney U test to study differences between categorical and continuous variables, respectively.
Patients who underwent surgery were selected for a survival analysis (logRank) and a Cox multivariate analysis after adjusting for relevant confounders. The level of statistical significance was set at p=0.05.

Results: 41,229 patients with EHCC were included: AC n=41,127 (99.76%) and SCC N=102(0.24%). SCC had a significantly larger median tumor size and more Grade 3 poorly or undifferentiated tumors (table 1). Median survival was 5.06 months for all SCC patients versus AC 11.07 months(p< 0.001). (Figure 1)
In a Cox multivariate analysis for overall survival (OS), tumor size (HR=1.001; 95%CI [1.001-1.002], p=0.000), positive resection margins (HR=1.875; 95%CI[1.761-1.995], p=0.000), age (HR=1.009; 95%CI [1.007-1.012], p=0.000), Charlson-Deyo score (HR=1.3; 95%CI[1.14-1.483], p=0.000), tumor grade (HR=1.671; 95%CI[1.536-1.817], p=0.000) and radiation therapy (HR=1.236; 95%CI[1.164-1.313], p=0.000) were positively associated with decreased survival for surgically managed cholangiocarcinoma. Chemotherapy had a favorable impact on survival (HR 0.687; 95%CI [0.65-0.725], p=0.000). While SCC group had a higher tumor size and grade, no difference in survival was found between SCC and AC patients treated surgically (HR=0.794; 95%CI= [0.439; 1.435], p =0,445).

Discussion: SCC is a rare histologic variant of EHCC with worse OS than AC. Surgery when indicated improves survival in EHCC, including SCC. Due to the low frequency of the SCC variant, more research is needed to better characterize this rare histologic type. We recommend an extensive workup for alternative primary sites when encountering SCC variant of EHCC given the paucity of cases.




Disclosures:


Jad Mitri, MD¹, Elena Panettieri, MD², Eduardo Vega, MD². P0027 - Squamous Cell Carcinoma of the Extrahepatic Bile Ducts: A National Cancer Database Analysis of a Rare Cholangiocarcinoma Histologic Variant, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.