Neoadjuvant Therapy Improves Survival in Resectable Pancreatic Cancer with Vein Abutment

New research suggests that chemotherapy before surgery—neoadjuvant therapy—improves survival rates for patients with pancreatic ductal adenocarcinoma (PDAC), even those initially considered candidates for immediate surgical resection. The findings, published in the Journal of the National Comprehensive Cancer Network (NCCN), challenge current guidelines and offer a potentially more effective treatment strategy for this aggressive cancer.

Challenging Conventional Wisdom

Pancreatic cancer is notoriously difficult to treat, often diagnosed at a late stage when curative options are limited. Historically, upfront surgery has been the standard of care for patients with “resectable” tumors—those that appear surgically removable. However, the NCCN guidelines define “upfront resectable” as tumors with 180 degrees or less of portomesenteric vein (PMV) abutment. This new study questions whether that classification is always optimal.

Researchers at the Mayo Clinic analyzed data from 1446 patients who underwent pancreatoduodenectomy (surgical removal of the pancreas) for upfront resectable PDAC between 2002 and 2023, across three Mayo Clinic sites. The study focused on the impact of PMV abutment—where the tumor contacts a major vein—and the sequence of treatment: surgery first versus chemotherapy first.

Survival Benefits of Neoadjuvant Therapy

The analysis revealed that PMV abutment, even minor involvement, was a significant predictor of poorer outcomes when patients underwent surgery first. Those with PMV abutment had a median overall survival (OS) of 19.2 months, compared to 27.6 months for those without vein involvement (P < .05). The rate of complete tumor removal (R0 resection) was significantly lower in the surgery-first group with PMV abutment—63.1% versus 87.2% without abutment (P < .05).

However, the picture changed dramatically with neoadjuvant therapy. Patients with PMV abutment who received chemotherapy before surgery achieved a median OS of 42.5 months, while those without abutment reached 51.6 months (P = .48). The benefit was particularly pronounced in patients treated more recently, since 2017, with modern chemotherapy regimens. In this group, patients without PMV abutment had a median OS of 45 months, while those with PMV abutment who underwent upfront surgery had a median OS of only 20.4 months (P < .05). The R0 resection rate also improved substantially with neoadjuvant therapy, reaching 91.4% for those with abutment and 94.0% for those without.

Mitigating Surgical Disparities

“Many patients with early-stage pancreatic cancer undergo surgery first because it is historically believed to be the best chance for cure,” explained Zhi Ven Fong, MD, MPH, DrPH, a surgical oncologist at Mayo Clinic in Arizona and co-senior author of the study, in a press release. “Our findings suggest that chemotherapy first, even in cases thought to be more straightforward, provides patients with the best opportunity for long-term survival.”

The study also examined the impact of neoadjuvant therapy on tumor size. Researchers observed a reduction in pathologic tumor size in both groups—those with and without PMV abutment—following preoperative chemotherapy. While some patients with PMV abutment required resection of the vein itself during surgery (35.6%), the study found that this aggressive surgical approach did not independently improve survival. Instead, the biological response to chemotherapy appeared to be the primary driver of better outcomes.

Study Details and Design

The study was a retrospective analysis, meaning it looked back at data already collected. Researchers included all patients from three Mayo Clinic sites who met specific criteria: nonmetastatic, upfront resectable PDAC as defined by NCCN guidelines (PMV abutment of 180 degrees or less without contour irregularity), and no arterial involvement. Patients were then categorized based on the presence or absence of PMV abutment and the order of treatment—surgery first or neoadjuvant therapy.

Neoadjuvant regimens typically involved multi-agent chemotherapy, such as gemcitabine plus nab-paclitaxel. The primary endpoint of the study was overall survival, with R0 resection rates and pathologic tumor characteristics serving as secondary endpoints.

Implications for Patient Care

Mark Truty, MD, a surgical oncologist at Mayo Clinic in Minnesota and co-senior author, highlighted the importance of these findings for patient counseling. “Our hope is that this study empowers both patients and clinicians to think carefully about treatment sequencing. We want people to know they have options, and that starting with chemotherapy may be the best path forward,” he stated.

These findings suggest a potential shift in the standard of care for upfront resectable pancreatic cancer. While further research is needed to confirm these results and refine treatment protocols, the study provides compelling evidence that neoadjuvant therapy can improve survival outcomes, particularly for patients with even minor vein involvement. This emphasizes the importance of individualized treatment plans and a careful consideration of all available options for patients facing this challenging diagnosis.

1. Tan PH, Thiels CA, Poruk K, et al. Redefining upfront resectable pancreatic ductal adenocarcinoma: should vein abutment matter? J Natl Compr Canc Netw. 2026;24(2):27-33. Doi:10.6004/jnccn.2025.7097
2. Corey C. Mayo Clinic study finds chemotherapy before surgery improves survival in early-stage pancreatic cancer. News release. Mayo Clinic News Network. February 9, 2026. Accessed February 16, 2026. Https://tinyurl.com/ypkywf63