Gallbladder Cancer Staging
Gallbladder cancer is staged according to the TNM 2010 system, which classifies disease based on depth of tumor invasion (T stage), lymph node involvement (N stage), and distant metastases (M stage). 1
Primary Tumor (T) Classification
The T stage defines the depth of tumor invasion through the gallbladder wall layers:
Tis (Carcinoma in situ): Cancer confined to the epithelial layer without invasion 1
T1a: Tumor invades the lamina propria only 1
T1b: Tumor invades the muscular layer 1
T2: Tumor invades perimuscular connective tissue with no extension beyond the serosa or into the liver 1
T3: Tumor perforates the serosa (visceral peritoneum) and/or directly invades the liver and/or one other adjacent organ or structure (stomach, duodenum, colon, pancreas, omentum, or extrahepatic bile ducts) 1
T4: Tumor invades the main portal vein or hepatic artery, or invades two or more extrahepatic organs or structures 1
Regional Lymph Node (N) Classification
The N stage categorizes lymph node involvement by anatomic location:
N0: No regional lymph node metastasis 1
N1: Metastases to nodes along the cystic duct, common bile duct, hepatic artery, and/or portal vein 1
N2: Metastases to periaortic, pericaval, superior mesenteric artery, and/or celiac artery lymph nodes 1
Clinical Staging Considerations
Lymph node involvement is present in 50% of all patients at presentation and is associated with poor surgical outcomes. 2
Peritoneal and distant metastases are present in 10-20% of all patients at presentation, representing stage IVB disease. 2, 3
Staging Workup Requirements
Complete staging must include the following components:
- Complete history and physical examination 1
- Blood counts and liver function tests 1
- Chest X-ray 1
- Abdominal imaging with sonography and CT scan or MRI 1
- Endoscopic retrograde or percutaneous transhepatic cholangiography 1
- Endoscopic ultrasonography, cholangioscopy, and laparoscopy when indicated 1
- Laparoscopy to determine presence of peritoneal or superficial liver metastases 2
Important Clinical Pitfalls
The 8th edition AJCC TNM staging system requires examination of at least six lymph nodes for accurate N staging, but 78.5% of patients have fewer than six lymph nodes examined. 4 In patients with inadequate lymph node examination, lymph node ratio-based staging (TNrM) may provide superior prognostic stratification compared to standard TNM staging. 4
Most gallbladder carcinomas (two-thirds) are not recognized preoperatively and are diagnosed incidentally after cholecystectomy for presumed benign disease. 5 This emphasizes the critical importance of complete pathologic examination of all cholecystectomy specimens.