Doctors arrive at a confirmed diagnosis of mesothelioma through a series of tests and procedures. In general, any cancer is diagnosed through a series of tests. Genetic testing, which is done in most cases to assess the cancer risk, does not apply here because in this cancer cells develop exclusively due to primary or secondary exposure to asbestos. In this way, mesothelioma differs from other types of cancers.

The procedure to diagnose mesothelioma includes:

  • medical history
  • occupational history (any occupational history that shows exposure to asbestos either primarily or secondarily)
  • blood tests
  • radiological and imaging tests and
  • confirmation by biopsy.

All these are important and play a useful role in mesothelioma diagnosis.

Medical history and evaluation of your symptoms

Your medical history, symptoms, and occupational history along with your history of exposure to risk factors become important for your doctor to suspect mesothelioma. He then carries out certain more specialized tests for mesothelioma.

Your doctor will ask about your profession to know if it entails any asbestos exposure. He will also want to find out if any of your family members or people you have lived with had any exposure to asbestos. These are the risk factors he will want to rule out.

Since the latency period of mesothelioma is long, 20 to 60 years, he will go long back to elicit your history.

He will ask you to check if you have symptoms of mesothelioma such as shortness of breath, chest wall pain, fatigue, fever, sweats, and weight loss.

After history taking is complete, he will proceed with the physical examination.

Physical examination

The general appearance of the mesothelioma patient may show that a mesothelioma patient appears fatigued.

When examining you physically, your doctor will look for telltale signs of any lumps felt over the chest or abdomen. He will look for ascites or pedal edema.

In malignant mesothelioma, physical findings of pleural effusion are usually noted upon percussion (dullness sound on percussion)

Auscultation of the lungs reveals decreased breath sounds. Any irregular beating of the heart or murmurs will make him suspicious of pericardial involvement.

Radiological or imaging tests

Chest x-ray.

A thickened pleura or pleural effusion seen on a chest x-ray can be indicative of pleural mesothelioma.

CT scan.

Computed Tomography scan or CT scan involves taking a series of x-rays of the cross section of the body part at various levels using computer processing.

This gives the trained radiologist a complete three-dimensional picture of the inside of the body. It is like comparing a loaf of bread sliced into a number of slices, which allows you to view the inside of the bread.

The patient may be injected with a dye or given one to drink. This is for more contrast to get a more clear picture of the inside of the body part which has been CT scanned.

The dye is harmless and well tolerated and gets excreted. However, it can cause an allergic reaction in those who are allergic to iodine or those who have bronchial asthma.

The doctor may therefore take your relevant history or may even do a sensitivity test to determine if you are allergic to the dye.

MRI

MRI or Magnetic resonance imaging is the use of magnetic waves to get a more detailed image of the body part to be investigated.

It shows a more detailed and contrasting picture than a CT scan. The various bones and the soft tissues of the body are more differently defined and give the radiologist a clearer image so that he is able to differentiate the normal tissue from the abnormal one and is able to confirm the presence of a mesothelioma tumor and its metastasis if any.

A contrast dye may be given to the patient to swallow. This dye does not contain iodine, thereby eliminating the chances of an allergic reaction.

Another advantage of MRI is that it does not expose the patient to radiation. However, MRI is contraindicated in patients with a pacemaker implant because the magnetic fields created by MRI can interfere with the functioning of the pacemaker.

PET scan

PET scan or Positron emission tomography is a new and more developed scan, which is used if the x-rays and CT scan do not give a conclusive diagnosis to the doctor.

In a PET scan, mildly radioactive glucose is injected into the vein of the patient. PET scan is then taken 2 hours later. Cancer areas are seen as more active than the normal surrounding tissue on the scan.

This helps distinguish between normal and cancerous tissue and detect metastasis.

Biopsy

The previous tests will conclude whether you need a biopsy or not. Biopsy for mesothelioma consists of histopathologically examining the fluid and tissue of the relevant mesothelium, under the microscope.

The fluid could be that of pleural effusion or peritoneal effusion or pericardial effusion. The fluid and the part of the suspected tissue are removed for examination by any of the following methods.

Fine needle aspiration

A fine long needle is inserted into the chest wall and the pleural fluid, which has built up due to inflammation in the pleural sac is aspirated and sent to the pathologist for examination of any abnormal cells. Similarly, peritoneal fluid can also be aspirated.

Thoracoscopy

Through a small incision in the chest wall, the doctor inserts a thoracoscope into the chest wall for a visual examination of the affected part.

He may then draw pleural fluid or take a small part of the suspected pleural membrane for histopathological examination, which can confirm a suspected case of mesothelioma. This procedure is done under local anesthesia.

Peritoneoscopy or laparotomy

Similarly, for a suspected case of peritoneal mesothelioma, a peritoneoscope is inserted into the abdomen and the peritoneal membrane is examined.

Peritoneal fluid and/or a small amount of peritoneal tissue may be removed for examination under the microscope.

Importance of biopsy in mesothelioma diagnosis

The only way to confirm a mesothelioma diagnosis is through the examination of cells from the suspected abnormal area through a biopsy.

The doctor collects the biopsy sample and sends it to a lab where the cytologist examines the sample under a microscope.

Cytotechnologists or cytologists are lab professionals who assess the patient’s cell samples and they are trained to notice cellular changes to accurately distinguish precancerous, malignant, and infectious conditions. A cytotechnologist and a pathologist usually work closely together.

If they find the properties of the biopsy sample consistent with those of mesothelioma, then the abnormal tissue may be diagnosed and confirmed as mesothelioma.

Blood tests to diagnose mesothelioma

Blood testing offers hope for an early diagnosis of mesothelioma. As mentioned early, symptoms of mesothelioma present in the late stages of mesothelioma, when treatment is palliative (for relief from symptoms) rather than curative.

The discovery of certain mesothelioma bookmarkers has made it possible to detect mesothelioma in the early stages.

Mesomark assay

This is a test in molecular biology, which determines the levels of SMRP in human blood or serum. SMRP stands for Soluble Mesothelin Related Peptide and is a protein or bookmarker that is otherwise also produced by mesothelioma cells. It shows elevated levels in malignant mesothelioma.

miRview test

miRview is a new molecular diagnostic test, which measures microRNA biomarkers to accurately differentiate mesothelioma from other cancers.

This test is specific to mesothelioma and can distinguish between the mesothelioma cancer cells those caused by lung cancer.

The test’s sensitivity is 100%, while the specificity is 94%, which is a better accuracy than any other test for mesothelioma.

Are there any screening procedures for mesothelioma?

Screening is a procedure of medical tests that doctors use to detect health conditions in the general population even if there are no signs or symptoms.

Screening tests help find mesothelioma early on, making treatment easier and prognosis better.

If you have a history of primary or secondary asbestos exposure, or you are engaged in a profession that puts you at risk, mesothelioma, screening can help save your life through early detection and prompt aggressive treatment.

Professions that are at risk include construction workers, boiler workers, shipbuilders, and workers from other industrial occupations.

The latent period for mesothelioma is late, 20 to 60 years after exposure to asbestos. With regular screenings, people at risk are able to receive professional monitoring to detect any abnormalities that might develop early before symptoms develop.

Although there’s no definite single mesothelioma screening test that can conclusively detect this cancer, your doctor may recommend the following noninvasive procedures.

They include:

  • Pulmonary function tests
  • Chest X-rays and CT scans
  • Blood tests to look for cancer biomarkers osteopontin and/or soluble mesothelin-related peptides. These are biomarkers, which people with mesothelioma often have in high concentrations in their blood.