What are the criteria for determining the resectability of a pancreatic tumor?

Criteria for Resectability of Pancreatic Tumors

Pancreatic tumors are classified as resectable, borderline resectable, or unresectable based on the degree of vascular involvement, with resectable disease requiring clear fat planes around major arteries (celiac axis, hepatic artery, SMA) and no venous involvement, while borderline resectable disease permits limited arterial contact (≤180° of SMA circumference) or reconstructable venous involvement. 1, 2

Resectable Disease Criteria

For a tumor to be considered resectable, all of the following must be present:

• No distant metastases (hepatic, peritoneal, pleural, or distant lymph nodes beyond resection field) on thorough radiographic assessment 1, 2
• Clear fat planes around all major arteries: celiac axis, hepatic artery, and superior mesenteric artery (SMA) with no tumor contact 1, 2
• No venous involvement: no abutment, distortion, tumor thrombus, or encasement of the superior mesenteric vein (SMV) or portal vein (PV) 1, 2
• Patient has adequate performance status to tolerate major pancreatic surgery 1, 2

Only 15-20% of patients present with resectable disease at diagnosis. 1, 2

Borderline Resectable Disease Criteria

Borderline resectable tumors have limited vascular involvement that may be technically resectable but carries higher risk of incomplete (R1/R2) resection:

Arterial Involvement (Borderline):

• SMA involvement ≤180° of vessel wall circumference 1, 2
• Short-segment hepatic artery encasement without extension to celiac axis 1, 2
• No celiac axis involvement 1

Venous Involvement (Borderline):

• Tumor abutment on portal vein or SMV with or without venous deformity 1, 2
• Limited encasement of mesenteric and portal vein with short-segment occlusion but suitable vessel for anastomosis above and below 1
• Teardrop deformity at tumor-vessel contact 1

Critical pitfall: Do not operate on borderline resectable disease upfront—these patients require neoadjuvant therapy first to increase the likelihood of R0 resection. 1, 2

Unresectable Disease Criteria

Tumors are unresectable when:

• Arterial involvement >180° of SMA or celiac axis circumference 1
• Any celiac axis encasement 1
• Unreconstructable venous occlusion without suitable vessel for anastomosis 1
• Distant metastases to liver, peritoneum, distant lymph nodes, or other organs 1, 2
• T4 disease involving celiac axis or SMA 1

Patients with distant metastases derive no survival benefit from resection. 1, 2

Essential Staging Workup

Before determining resectability, obtain:

• CT angiography with pancreatic protocol to assess each vessel individually (SMA, celiac axis, hepatic artery, PV, SMV) 1, 2
• MRI for indeterminate hepatic lesions or cystic pancreatic neoplasms 2
• EUS-guided biopsy for tissue diagnosis and complementary staging information 1, 2
• CA 19-9 level as the most useful tumor marker 1

CT and MRI can determine non-resectability with >90% positive predictive value, but have insufficient predictive value (<50%) to affirm resectability. 1

Surgical Goals and Margin Assessment

The primary goal is R0 resection (negative margins), which is the strongest prognostic indicator for survival. 1, 2

Seven margins must be assessed:

• Anterior and posterior surfaces 2
• Medial/superior mesenteric groove 2
• SMA margin 2
• Pancreatic transection margin 2
• Bile duct margin 2
• Enteric margin 2

SMV-PV resection with reconstruction is acceptable to achieve R0 resection, though it is associated with worse outcomes due to tumor aggressiveness. 2

Critical Decision-Making Principles

Multidisciplinary consultation is mandatory for all resectability decisions, involving surgeons, medical oncologists, radiation oncologists, and radiologists. 1, 2

Refer to high-volume centers (performing ≥15-20 pancreatic resections annually), where resection rates are 20% higher and mortality significantly lower. 1, 2

Reassess resectability after neoadjuvant therapy in borderline resectable or initially unresectable patients, as tumor downstaging can convert unresectable disease to resectable. 1, 2, 3

Avoid futile resections: R2 resections (macroscopic residual disease) offer no survival benefit over bypass procedures and carry significantly higher morbidity. 4

Common Pitfalls to Avoid

• Do not attempt upfront surgery on borderline resectable disease—neoadjuvant therapy first improves R0 resection rates 1, 2
• Do not operate on tumors with arterial involvement >180°—this predicts unresectability 1, 2
• Do not proceed with surgery if R0 resection is unlikely—incomplete resections offer no survival advantage over non-operative management 1
• Do not rely solely on imaging—up to 50% of radiologically resectable tumors are found unresectable at surgery 5
• Consider diagnostic laparoscopy for radiologically resectable tumors >4.8 cm in diameter, as these have 5-fold higher unresectability rates 5