Metastasis and spread of pancreatic cancer

The pancreas is prone to metastasis due to its thin capsule and rich lymphatic and blood supply. There are four ways for pancreatic cancer to metastasize: lymphatic metastasis, blood metastasis, infiltration, and metastasis around nerves.

(I) Lymphatic metastasis

Regional lymph node metastasis, in addition to metastasis to the retroperitoneum and the lymph nodes around the pancreas, also metastasizes to different areas due to different tumor locations. Pancreatic head cancer often metastasizes to the lymph nodes below the pylorus and around the superior mesenteric artery, while pancreatic body and tail cancer first metastasizes to the splenic hilar lymph nodes, and hepatic hilar lymph node metastasis is not uncommon. Finally, it can widely metastasize to the lymph nodes around the celiac artery, the greater and lesser curvatures of the stomach, and the abdominal aorta, and can also metastasize to the mediastinal and supraclavicular lymph nodes.

(II) Hematogenous metastasis

It often metastasizes to the liver through the portal vein and then to the lungs, and eventually to most organs in the body, including the bones, kidneys, brain, adrenal glands, and subcutaneous tissue.

3. Direct Infiltration and Metastasis

The most common disease involves adjacent organs. Pancreatic head cancer is prone to invade the lower end of the common bile duct, portal vein, duodenum, and transverse colon. Pancreatic body and tail cancer can invade the splenic vein, leading to portal vein thrombosis and portal hypertension. After the pancreatic capsule is invaded, cancer cells fall off and cause intra-abdominal implantation and metastasis.

4. Metastasis along the perineurium

It is most common in pancreatic body cancer, which invades the celiac plexus and metastasizes along the lymphatic vessels around the retroperitoneal nerves, causing stubborn back pain.

The order in which pancreatic cancer metastasizes to various sites through the above four pathways is roughly the same in various reports. Frantz analyzed 850 cases of pancreatic cancer metastasis and divided them into the following categories according to the number of metastatic sites:

① Common metastatic sites are local lymph nodes, liver, peritoneum and lungs;

② The more common sites of metastasis are the adrenal gland, duodenum, kidney, stomach, gallbladder, small intestine and spleen, in addition to bones (skull, spine, ribs, sternum and mandible), pleura and diaphragm;

③ Uncommon metastatic sites are the brain, heart and pericardium, skin, subcutaneous tissue, ovaries, uterus, bladder, and thyroid gland;

④ Rare metastatic sites are the testicles, epididymis, prostate, ureter, spinal cord, esophagus, skeletal muscle, parotid gland, breast, umbilicus and rectum. In short, in addition to local lymph node metastasis, pancreatic head cancer metastasizes to the liver in the early stage, and pancreatic body and tail cancer easily spreads to the abdominal cavity.