Relationship Between Radiographic and Pathological Portal Vein-Superior Mesenteric Vein Involvement in Neoadjuvant...

The relationship between the radiographic portal vein-superior mesenteric vein (PV-SMV) involvement and pathological PV-SMV (pPV) invasion has been established in upfront surgery cases of pancreatic cancer (PC); however, evidence remains limited for patients receiving neoadjuvant therapy (NAT). This study aimed to evaluate the association of radiographic findings with pPV invasion in patients treated with NAT, and to examine whether this association differs between patients treated with neoadjuvant chemotherapy (NAC) and neoadjuvant chemoradiotherapy (NACRT).

We retrospectively analyzed patients with PC whose tumors contacted the PV-SMV on radiographic imaging before or after NAT. The relationship between radiographic findings and pPV invasion was evaluated in subgroups defined by pre- and post-NAT imaging findings.

Tumor size, PV-SMV contact length, and contact angle were significantly reduced in post-NAT imaging. Radiographic PV-SMV involvement showed limited association with pPV invasion in the entire cohort. The overall pPV invasion rate was 15% and did not differ between the NAC and NACRT groups (17% vs. 13%, p = 0.790). Among patients with a pre-NAT tumor size of < 20 mm, the pPV invasion rate was significantly lower in the NACRT group than in the NAC group (29% vs. 0%, p = 0.007). This difference was not observed in patients with a pre-NAT tumor size ≥ 20 mm (12% vs. 19%, p = 0.438). Across other radiographic classifications, pPV invasion rates remained comparable between treatment groups.

The association of radiographic findings with pPV invasion differs between patients treated with NAC and NACRT in patients with small tumors.