How is pancreatic cancer diagnosed?

In response to a question on

Pancreatic cancer can be difficult to diagnose; sometimes it causes no symptoms, and the symptoms that do occur can be caused by many other condiitons.

Jaundice (skin and eyes turning yellow), particularly without any fevers or pain, is one symptom that has a significant chance of being caused by a cancer of the pancreas, the bile duct or the surrounding organs. However, many people with pancreatic cancer do not develop jaundice—it depends very much on which part of the pancreas is affected. If the cancer blocks the bile duct—the tube that carries bile from the liver to the part of the intestine called the duodenum—then jaundice is likely to occur. There are, however, other causes of jaundice, such as gall stones or hepatitis.

Other pancreatic cancer symptoms are non-specific and are more commonly caused by other conditions. Abdominal or back pain; weight loss; and vomiting are some examples.

If there is a suspicion of pancreatic cancer, tests are required to evaluate the situation. The tests can include
Imaging studies such as an ultrasound, a CT (CAT) scan or an MRI of the bile ducts and panreas
Blood tests for tumour markers which can help diagnose pancreatic cancer. Tumour markers are proteins that are produced in excess by some cancer cells, and different cancers tend to produce different tumour markers. They are also called Cancer Antigens. The test that is most useful in pancreatic cancer is cancer antigen 19-9, or CA 19-9. Often additional tumour markers are checked at the same time. Autoimmune markers such as immunoglobulin G4 (IgG, IgG4) may also be tested, as autoimmune pancreatitis (an inflammatory condition caused by the body's immune cells attacking the pancreas) can mimic pancreatic cancer.
Endoscopic ultrasound — an ultrasound performed internally, under a light anaesthetic, using a flexible telescope passed through the mouth and stomach. The internal ultrasound is more accurate than an external ultrasound, and allows a mass in the pancreas to be biopsied without risking spreading cancer.
In general, external biopsies should be avoided, as endoscopic ultrasound allows biopsies to be performed without risking spread of the cancer. However if the cancer has already spread (metastasised) to the liver or elsewhere in the body, an external biopsy is acceptable and is often easier to organise.
It is not always possible to diagnose pancreatic cancer, even with these extensive tests. Sometimes a suspicious lump in the pancreas is removed surgically, without a diagnosis having been made. Whilst this is not ideal, it is preferable to missing a cancer, or not reaching a diagnosis until a cancer has grown or spread.

Some more resources on pancreatic cancer include:

Cancer Council:

The Australian Familial Pancreatic Cancer Cohort, which may useful if you are looking into the diagnosis of pancreatic cancer because of a family history of cancer of the pancreas:

I hope this helps!