What occurs to a person with..

So.. I have a friend whose grandpa has pancreatic cancer, and I understand that he gets swollen and red, and he IS currently in the hospital under treatment. I want to know what causes the swelling? Is it the swelling of an organ, something in his bloodstream? Can someone clarify this? oh, and also how long does it take for the swelling to decrease?

Ascites (pronounced ah-site-eez) is the accumulation of excessive fluid in the abdominal lining, called the peritoneum. This extra fluid causes the belly to become swollen and distended. Cancer accounts for approximately 10% of all cases of ascites and can occur when cancer has spread to the peritoneum from its original site. Most cases of cancer-related ascites occur in individuals with cancers of the breast, ovaries, colon, stomach or pancreas. It is especially common in individuals with advanced metastatic pancreatic cancer.

Possible Causes of Ascites

If the cancer has spread to the peritoneum in the abdomen, the lining can become irritated. To soothe this inflammation, the peritoneum produces fluid which becomes trapped within the abdomen. As the fluid accumulates, the abdomen swells.
If the cancer has spread to the liver or the portal vein leading to the liver, blood pressure can rise within the liver impairing circulation and lead a build-up of fluid in the abdomen.
If the liver is damaged it may produce less blood protein, which disrupts the body’s fluid balance, causing fluids to collect in body tissues including the abdomen.
If the cancer blocks the lymphatic system, excess fluid is unable to be efficiently drained and results in fluid build-up in the abdomen.