Prognostic Significance of Radiological Adjacent Organ Invasion in Resectable Left-Sided Pancreatic Cancer

The resectability of pancreatic cancer depends on the extent of vascular involvement. Left-sided pancreatic cancer (LPC) rarely invades major vessels but frequently involves adjacent organs. This study aimed to assess the prognostic significance of radiological adjacent organ invasion (RAOI) in resectable LPC.

This study included 162 patients who underwent distal pancreatectomy for resectable LPC between 2002 and 2020. Radiological adjacent organ invasion was defined as contact of the primary tumor or a continuous soft tissue density to the adjacent organs (stomach, adrenal gland, colon, or liver) on computed tomography. Clinicopathological factors and survival outcomes were compared between the RAOI (+) (n = 17) and RAOI (-) (n = 145) groups.

The RAOI (+) group had significantly higher CA19-9 levels (279 vs. 33 U/mL, p = 0.005), larger radiological tumor sizes (37 vs. 21 mm, p < 0.001), and more frequently positive peritoneal cytology results (41% vs. 8%, p = 0.002). Overall survival (OS) in the RAOI (+) group was significantly worse than that in the RAOI (-) group (median survival time [MST], 25.9 vs. 67.2 months, p < 0.001). Among patients with negative cytology results (n = 141), OS was still significantly worse in the RAOI (+) group (MST, 33.5 vs. 71.9 months, p = 0.001). Multivariate analysis revealed CA19-9 levels ≥37 U/mL and RAOI as independent risk factors for poor OS.

Radiological adjacent organ invasion is an independent negative prognostic factor in resectable LPC and is associated with early systemic dissemination and worse survival outcomes. Radiological adjacent organ invasion (+) LPC may be considered a borderline resectable disease that requires intensive multimodal treatment strategies.