What factors render a pancreatic mass unresectable?

From the Guidelines

A pancreatic mass is considered unresectable if it is locally advanced or metastatic, with key factors including distant metastases, vascular involvement, particularly of the celiac axis, superior mesenteric artery (SMA), and portal vein (PV), and tumor size or location that precludes complete resection with negative margins.

Key Factors for Unresectability

• Distant metastases: presence of metastases to other organs or tissues, such as the liver, lungs, or peritoneum 1
• Vascular involvement: tumor involvement of critical vessels, including:
  • Celiac axis
  • Superior mesenteric artery (SMA)
  • Portal vein (PV)
  • Superior mesenteric vein (SMV) 1
• Tumor size or location: tumors that are too large or located in a way that makes complete resection with negative margins impossible 1
• Borderline resectable tumors: tumors that are considered borderline resectable may be downstaged with neoadjuvant therapy, but are initially considered unresectable due to high risk of positive surgical margins 1

Diagnostic Criteria

• CT or MRI: imaging modalities used to assess tumor resectability, with criteria including:
  • Vessel tumor contact <180° without deformation
  • Vessel tumor contact >180° without deformation
  • Vessel deformation (i.e. abutment)
  • Tear drop deformation at the tumor contact (i.e. distortion) 1

Management

• Neoadjuvant therapy: may be used to downstage borderline resectable tumors, increasing the chances of an R0 resection 1
• Surgical resection: considered for patients with resectable tumors, with the goal of achieving negative margins 1
• Chemotherapy and chemoradiation: used to treat patients with unresectable disease, with the goal of improving symptoms and prolonging survival 1

From the Research

Factors Rendering a Pancreatic Mass Unresectable

• Tumor infiltration into adjacent arteries (e.g. hepatic artery, superior mesenteric artery and celiac artery) is a significant factor, as surgical resection is often technically possible but associated with an increased morbidity and mortality 2
• Involvement of vessel to tumor that exceeds one-half circumference of the vessel is highly specific for unresectable tumor 3
• Tumor size (≥30 mm) and abnormalities in the levels of DUPAN-2 and CA 125 are independent predictors of unresectability 4
• Distant metastases and locally advanced tumors are also factors that render a pancreatic mass unresectable 5, 6, 4
• The presence of triple positive findings (tumor size ≥30 mm, abnormalities in the levels of DUPAN-2 and CA 125) presents with the highest sensitivity (78.8%) for unresectability 4

Diagnostic Criteria

• A grading system for tumor involvement of the major vessels in patients with pancreatic adenocarcinoma can be based on the degree of circumferential contiguity of tumor to vessel 3
• Radiological therapy response evaluation is challenging after neoadjuvant therapy as it is not usually associated with a radiologically detectable reduction in tumor volume 2
• Precise evaluations for distant metastasis and locally advanced unresectability are necessary for patients with predicting factors for unresectability 4