How accurate is helical computed tomography for clinical staging of pancreatic cancer?

BACKGROUND

Our goal was to determine if findings on an index computed tomography (CT) scan would correlate with survival in patients with pancreatic adenocarcinoma. We know that as this tumor extends out of the gland, survival decreases. Are there any CT findings that assess tumor extension sufficiently that also correlate with survival? Once identified, these CT areas would be the best factors to clinically stage patients.

METHODS

Between 1993 and 1997, 160 patients with biopsy-proven adenocarcinoma of the pancreatic head were included if an index helical CT scan and clinical follow-up were available. All CT scans were reviewed by the same radiologist blinded for outcomes. CT scans were interpreted using a graded extension of tumor out of the pancreatic head in four areas: retroperitoneum (RP); anterior pancreatic capsule (S); portal/superior mesenteric veins (PV); and celiac/superior mesenteric arteries (A). Extension of tumor was graded as follows: Grade 0 (negative margin); 1 (suspicious); 2 (positive); or 3 (extensively involved). Also recorded and graded were signs of metastases: nodal enlargement > or =1.5 cm (N); and lesions consistent with hepatic metastases (H). Survival was compared between grades for each CT area using the methods of Kaplan and Meier and relative risk estimates of death (Cox regression models).

RESULTS

Compared with grade 0, the following CT areas had significantly decreased survival curves: grade 1 (only S and A), grade 2 and 3 (RP, PV, S, A). N and H did not correlate with survival unless > or =1.5 cm nodes were in the liver or splenic hilum or there were multiple liver nodules.

CONCLUSION

Although postoperative microscopic H or N involvement is a reliable prognostic sign, only extensive CT involvement of H or N predicts survival preoperatively. A better CT finding that predicts decreased survival preoperatively was extension out of the pancreatic head (especially S or A). Clinical methods of staging should use CT areas such as S, A, PV, and RP, and not H and N.