Mesothelioma Diagnosis

Imaging Tests for Mesothelioma

Following a physical exam, your doctor will likely order imaging scans. X-rays can rule out pneumonia and other illnesses by imaging dense tissues.

CT, PET, and MRI scans provide detailed pictures of soft tissues. They help oncologists determine if you have any tissue abnormalities that look like they could be cancerous:

• A CT scan images the inside of the body using electromagnetic energy. A doctor can see most tumors with it.
• A similar type of image can be produced with an MRI, or a magnetic resonance image. It uses magnets and electromagnetic energy to create an image of internal structures.
• A PET scan detects areas of the body with high metabolic activity, an important characteristic of many cancerous cells.

Your doctors may need to use a combination of two or more imaging tests to be sure of the presence of tumors and their locations.

Tissue Biopsies

If an imaging scan does show abnormal tissue or suspicious growths, the next step is to perform a biopsy. The image will show an oncologist locations where tissue may be cancerous, but it cannot confirm tumors.

The suspected areas can be sampled through a biopsy to test the tissue or fluid from an abnormality and determine if it is cancerous or benign. There are several methods for performing a biopsy:

• Fine-needle aspiration. This procedure uses a long, thin needle inserted into one of the imaged tumors. It withdraws a small amount of tissue or fluid for examination.
• Thoracoscopy. This involves a long flexible tube, called an endoscope, that is inserted through an incision in the wall of the chest, back, or abdomen.
• Endoscopy. An endoscope can also remove tissue from the lymph nodes in the throat to determine if the cancer cells have spread here.
• Open-surgical biopsy. Sometimes an oncologist needs more tissue than the less invasive procedures can provide. The patient goes under general anesthesia and the doctor surgically removes tissue for testing.

Blood Tests and Early Detection

Currently, a combination of imaging and biopsy gives specialists the most accurate way to diagnose mesothelioma. Pathologists look at tissue samples from biopsies under a microscope to identify cells and determine if they are malignant.

There is no definitive blood test for mesothelioma. Some blood tests can be useful, but not conclusive. For example, someone with mesothelioma is likely to have higher levels of certain proteins in the blood called osteopontin and mesothelin. But, there could be other explanations for elevated levels.

The latest research on diagnosing mesothelioma has focused on blood tests that may give a patient a more accurate and earlier diagnosis. One new test, called the SOMAmer test, can detect over 1,000 different proteins in the blood.

In trials with this test, doctors diagnosed 90 percent of patients who were already known to have mesothelioma. They were able to rule out the disease in 95 percent of people known not to have it. In other words, this test has the potential to diagnose patients more accurately and earlier than ever before.