Anatomy and Staging: The Role of Blood Vessels

In many cancers, “staging” is just about how large a tumor is or how many lymph nodes it has reached. In pancreatic cancer, however, the most important local-anatomic factor is resectability—a classification that describes whether a surgeon can safely remove the tumor based on its relationship to nearby major blood vessels ^[1][2]. This mapping dictates much of your initial treatment path, determining whether you start with surgery or with chemotherapy.

The Importance of Pancreas-Protocol Imaging

To get an accurate map, your doctors need a specialized scan called a pancreas-protocol CT. Unlike a standard CT, this scan uses very thin “slices” and timed IV contrast to capture the pancreas when blood flow through the arteries and veins is at its peak ^[3][4]. This allows radiologists to see exactly how much of a vessel’s circumference is touched by the tumor, measured in degrees (e.g., less than or more than 180°) ^[1]. In some cases, a liver MRI may also be used to double-check for small spots that a CT might miss ^[5][3].

The Categories of Resectability

Your team will assess your cancer based on your scans. These categories describe the local anatomy, provided there is no distant spread.

1. Resectable: The tumor does not touch any major arteries (like the SMA or Celiac Axis) and has minimal or no contact with major veins (like the Portal Vein or SMV) ^[6][2]. In these cases, upfront surgery may be an option, provided there is no metastatic spread.
2. Borderline Resectable: The tumor is “leaning” against one or more major vessels. It may abut a vessel or cause some narrowing of a vein ^[1][7]. While surgery might be possible, it is difficult to get “clean margins” (removing all cancer cells) immediately. Most patients in this group receive chemotherapy first (neoadjuvant therapy) to shrink the tumor away from the vessels ^[8][9].
3. Locally Advanced (Unresectable): The tumor has extensively involved a major artery or has blocked a vein so severely it cannot be reconstructed safely ^[7][9]. Surgery is generally not safe as an initial step, and the focus is on intensive systemic treatment to control the disease locally.
4. Metastatic: The cancer has spread to distant organs, such as the liver, lungs, or the lining of the abdomen (peritoneum) ^[1]. In this stage, surgery to remove the primary tumor in the pancreas is usually not performed because the focus shifts to treating the cancer throughout the entire body.

Anatomic vs. TNM Staging

You may also see an AJCC TNM stage (e.g., T2N1M0) on your reports. While these numbers remain highly important to help doctors predict long-term outlooks (prognosis) and guide systemic treatment, they do not always tell the full story of what a surgeon can do ^[1][10].

• T (Tumor): Size of the tumor and where it has grown ^[11].
• N (Node): Whether the cancer has spread to nearby lymph nodes ^[11].
• M (Metastasis): Whether it has spread to other organs ^[11].

Because imaging sometimes “under-stages” the disease—missing tiny cells in lymph nodes—your surgical team relies heavily on the resectability categories described above alongside TNM to decide if, when, and how to operate ^[10].

Why Vessels Matter

The pancreas is surrounded by a “highway system” of critical blood vessels that supply blood to your intestines and liver. Contact thresholds depend on contour irregularity, occlusion, and institutional criteria.

• Arteries (SMA, Celiac Axis): These carry oxygen-rich blood. If a tumor wraps too tightly around them, they cannot be safely cut and sewn back together ^[7].
• Veins (Portal Vein, SMV): These carry blood away from the intestines. Surgeons at high-volume centers can often “reconstruct” these veins by removing a piece and replacing it with a graft if the tumor involvement is limited ^[1][12]. This is why vein involvement is often considered “borderline” while heavy artery involvement is more likely to be “locally advanced.”