Mesothelioma Diagnosis

Imaging Tests for Mesothelioma

Following a physical exam, your doctor will likely order imaging scans. X-rays help 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 tumors:

• A CT scan images the inside of the body using electromagnetic energy. A doctor can see most tumors this way.
• A similar type of image can be produced with an MRI, or a magnetic resonance image. This uses magnets and electromagnetic energy to create a picture of internal structures.
• A PET scan is an imaging technique that detects areas of the body with high metabolic activity, which is often characteristic of cancerous cells.

You may need a combination of two or more imaging tests to be sure of tumor locations.

Tissue Biopsies

If an imaging scan does show something abnormal, the next step is to perform a biopsy. The image will show an oncologist the probable locations of cancerous tissues, cancer cells, and tumors.

The suspected areas can then be sampled by biopsy so that the tissue or fluid from a tumor can be tested to determine if it is cancerous or benign. There are several methods for performing a biopsy:

• Fine-needle aspiration. This involves a thin, long, 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, inserted through an incision in the wall of the chest or back, or in the abdomen for peritoneal mesothelioma.
• Endoscopy. An endoscope can also retrieve tissue from the lymph nodes in the throat to determine if the cancer cells have spread.
• Open-surgical biopsy. Sometimes an oncologist needs more tissue than the less invasive procedures can provide. In this case the patient goes under general anesthesia and the doctor removes more tissue for testing.

Blood Tests and Early Detection

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

Unfortunately there is no quick blood test for mesothelioma. There are blood tests that 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 into 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, detects over 1,000 different proteins in the blood.

In trials with this test doctors were able to diagnose 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 accurately and earlier than ever before.