Imaging tests are important in diagnosing pancreatic cancer, but they cannot determine with 100% certainty if an abnormal mass or tumor is actually cancer or the type of cancer. The doctor must obtain and analyze a tissue sample (biopsy) of the tumor in order to determine the exact diagnosis. A pathologist looks at tissue samples of the tumor under a microscope to determine if cancer cells are present. The shape, size and arrangement of the cancer cells may help determine the type of pancreatic cancer. However, not all biopsies provide a conclusive (definite) result.
The most common procedure to obtain samples of a pancreatic tumor is called Fine-Needle Aspiration (FNA). An FNA can be performed by inserting a needle through the abdomen or by inserting an endoscope (a thin, lighted tube) down the patient’s throat and passing a needle through the endoscope to the pancreas.
The procedure that inserts a needle through the abdomen is called a percutaneous FNA. During this procedure, a numbing substance and a cleaning solution are applied on the skin. Then, a thin needle is inserted through the abdominal wall and directed into the pancreas to obtain cells from the tumor. The doctor uses the image from a CT scan or ultrasound to guide placement of the needle.
The procedure that uses an endoscope to collect tumor samples is called EUS-guided FNA. This procedure is performed during an endoscopic ultrasound (EUS). This process involves imaging the tumor with ultrasound, passing the needle through an endoscope (which is inserted down the patient’s throat), and directing the needle to the pancreas through the stomach or duodenum. Unlike percutaneous FNA, there is no discomfort with this procedure. EUS-guided FNA, performed by a specially trained and experienced doctor, is the most accurate biopsy method for the pancreas, in most circumstances.
Other biopsy methods, such as a brush biopsy or forceps biopsy, can be performed during an ERCP. In a brush biopsy, a small brush is passed through the endoscope to rub off cells from the bile duct or pancreatic duct. The chance of getting a diagnosis of pancreatic cancer with ERCP brushings is generally lower than with other methods.
In a forceps biopsy, forceps (tongs) are passed through the endoscope to grasp and extract a small piece of the tumor.
Lastly, a tumor sample can also be taken during surgery.
Sometimes, the needle or brush used in the biopsy procedure may miss its target, which could lead to a noncancerous diagnosis even when cancer cells are present in the pancreas. Because treatment for pancreatic cancer depends on the specific type of pancreatic cancer, it is generally recommended to have a conclusive diagnosis before starting chemotherapy and/or radiation. However, in some cases, if the tumor is surgically resectable and other tests and symptoms indicate pancreatic cancer, the surgeon may elect to proceed with surgery even if the biopsy is inconclusive.
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