How do physicians diagnose bile duct cancer?
History and physical examination are key clues for the diagnosis of bile duct cancer. Painless jaundice (yellow/orange coloring of the skin and eyes) may be the only initial clue. The history often includes reviewing alcohol use, drug use, or recent illnesses that may be associated with hepatitis, or inflammation of the liver. Other cholangiocarcinoma symptoms may include weight loss, loss of appetite, weakness, loss of energy, and easy bruising or bleeding (factors that clot the blood are manufactured in the liver and loss of liver function may decrease the clotting factors in the bloodstream).
The physical examination may be useful in detecting tenderness in the abdomen, especially in the right upper quadrant beneath the ribs (where the liver is located). A quarter of patients with bile duct cancer will have an enlarged liver that can be palpated or felt on exam. During general exam, the patient is often jaundiced, having yellow-tinged skin. This may be seen most easily in the white portion (sclera) of the eyes or under the tongue.
Blood tests are often ordered to assess liver function. Liver enzymes (AST, ALT, GGT, alkaline phosphatase), bilirubin levels, complete blood count, electrolytes, BUN and creatinine, and INR/PTT (international normalized ratio/partial thromboplastin time), and PT (prothrombin time).
There is no blood test that can specifically diagnose bile duct cancer. The diagnosis is confirmed by tissue sample obtained by biopsy by a surgeon, gastroenterologist, or interventional radiologist and a pathologist using a microscope to exam the cells obtained by that biopsy sample.
Imaging may be used to evaluate the structure of the liver, gallbladder, bile ducts, and other surrounding organs. Tests like ultrasound, CT scan, and MRI may be performed to look for a tumor and its location.
Endoscopic retrograde cholangiopancreatography (ERCP) is a specialized test used to examine the bile duct as it enters the duodenum. ERCP is performed by a gastroenterologist using a fiberoptic camera at the end of a flexible viewing tube. The tube is passed through the mouth and threaded through the stomach into the first part of the small intestine where the common bile duct enters. This test is commonly performed to examine the lining of the esophagus and stomach, but is also very effective in detecting conditions that affect the bile ducts, including bile duct cancer, gallstones stuck in the bile duct, and abnormal narrowing of the bile duct. Dye can be injected through the tube into the bile duct opening to outline the bile ducts and detect obstruction. Biopsies or cell washings can be obtained to look for cancer cells. If a blockage is found, during the same procedure the gastroenterologist may be able to place a stent to keep the duct open and allow bile to drain.
Sometimes, an interventional radiologist may obtain a tissue biopsy by threading a needle through the skin into the liver.
Once the diagnosis of bile duct cancer is made, it is important to stage the cancer to help direct potential treatment. The three parts of TNM staging include the following:
- T is for the primary tumor and how much it has grown locally and invaded other structures. For a bile duct tumor, this includes the liver, gallbladder, pancreas, stomach, and intestine.
- N is for the lymph nodes that are involved. The more nodes involved and the farther the distance from the bile duct, the more severe the cancer.
- M is for metastasis. Has the tumor spread to other parts of the body?
Cancer can be staged from 0 to 4, where 0 is no tumor, 1 is local tumor with no spread to lymph nodes or other parts of the body, and 4 is significant local growth and lymph node involvement and spread to other parts of the body.
While staging is important, as well as detecting tumor spread beyond the liver and bile duct, often the critical staging questions can only be answered at surgery. During an operation, the surgeon can decide whether or not the whole tumor can be resected or removed. Survival rates are markedly improved if complete resection is possible.