Prognostic Impact of Radiological Splenic Artery Involvement in Pancreatic Ductal Adenocarcinoma of the Body and Tail.

BACKGROUND

Splenic artery (SpA) involvement heralds poor prognosis in pancreatic ductal adenocarcinoma (PDAC) of the body and tail but is not included in the resectability criteria. This study evaluated the prognostic impact of radiological SpA involvement in PDAC of the body and tail.

METHODS

Preoperative computed tomography images of patients who underwent distal pancreatectomy for resectable PDAC of the body and tail (n = 242) at our hospital between 2004 and 2018 were graded according to splenic vessel involvement status as clear, abutment, or encasement. Clinicopathological prognostic factors and overall survival (OS) and recurrence-free survival (RFS) rates were compared between the three groups. The prognostic value of radiological involvement status was assessed using Harrell's concordance statistic (C-index) and time-dependent receiver-operating characteristic curve analysis and compared with pathological findings.

RESULTS

The diagnostic concordance rate was 0.87 (weighted κ statistic). Prognosis worsened with progression from clear, abutment, to encasement status. SpA encasement (hazard ratio [HR] 1.97, p = 0.04) predicted poor OS in multivariate Cox hazard regression analysis. SpA abutment (HR 1.77, p = 0.017) and encasement (HR 1.86, p = 0.034) independently predicted poor RFS. Splenic vein abutment and encasement were not significant predictors of poor OS or RFS. SpA encasement without adjuvant chemotherapy had the poorest prognosis because of early distant metastasis. The prognostic value was higher for radiological SpA involvement than for pathological SpA invasion.

CONCLUSIONS

Radiological SpA involvement status is a meaningful and reproducible prognostic indicator that can be used preoperatively for determining the treatment strategy in PDAC of the body and tail.