Staging is the process of finding out how far the mesothelioma cancer has spread. Doctors determine which treatments to use based on the mesothelioma stage, or the severity of the disease. Staging of mesothelioma is based on imaging studies such as x-rays, CT scans, and MRI scans.

To keep a track of mesothelioma cancer, the extent of its spread and the size of tumor(s); mesothelioma has been divided into a few stages or staging systems. These mesothelioma staging systems keep a track of the development of cancer in the human body. The tests and scans when diagnosing cancer give some information about the stage. It is important because treatment is often decided according to the stage of a cancer.
Some elements common to most staging systems are:
• Location of the primary tumor.
• Size and number of the tumors.
• Lymph node involvement.
• Cell type and tumor grade.
• Metastasis.

Many cancer registries, such as the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (SEER) use summary staging, a system used for all types of cancer. Summary staging groups cancer into five main categories:

• In situ – cancer that is present only in the layer of cells in which it began.

• Localized – cancer that is limited to the organ in which it began with no evidence of spread.

• Regional – cancer that has spread from the primary site to nearby lymph nodes or organs.

• Distant – cancer that has spread from the primary site to distant lymph nodes or organs.

• Unknown – cases where not enough information exists to indicate stage.

Biopsy:

If, after performing all above tests, a doctor suspects mesothelioma, a biopsy should be taken to confirm the mesothelioma diagnoses.

If tests and health history are consistent with mesothelioma, a biopsy allows the doctor to make a conclusive diagnosis. The biopsy is an effective diagnostic tool, but is not used first because the removal of sample of cells or tissue is more invasive than a simple X-ray or blood draw.

The most definitive test for diagnosing mesothelioma is a biopsy (tissue sample) of affected or suspicious tissues. In that doctor who specializes in diagnosing and treating cancer removes sample of tissue for microscopic examination by a pathologist. The pathologist usually also looks for the rate of growth and strength of the tumor.

Types of biopsies:

A biopsy may be done in different ways, depending on where the abnormal area is located.

•Fine-needle aspiration biopsy: The physician uses a thin needle to remove a sample of possibly-diseased cells.

•Thoracotomy: In this an incision or small cut is made by physician between two ribs to check inside for signs of disease and to collect a tissue sample.

•Thoracoscopy: If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure the incision is made by physician between two ribs and inserts a thin, lighted tube into the chest called a thoroscope. The tube contains a tool to collect cells for examination under a microscope. This test is usually done in a hospital using a local anesthetic or painkiller. If fluid has found in the chest, doctor may drain the fluid out of the body by putting a needle into the chest and using gentle suction to remove the fluid. This is called thoracentesis.

•Peritoneoscopy and laparotomy: If the cancer is found in the abdomen, the doctor may perform peritoneoscopy and laproscopy. These procedures are similar to the thoracoscopy, but the incision is made in the abdominal wall. A thin, lighted tube is used to examine inside the abdomen is called a peritoneoscope. The peritoneoscope is put into an opening made in the abdomen and to collect cells for examination under a microscope. Before the test is done, a local anesthetic will be given. If fluid has collected in your abdomen, your doctor may drain the fluid out of your body by putting a needle into your abdomen and using gentle suction to remove the fluid. This process is called paracentesis.

After the sample has been removed, it will be sent to a pathologist, a physician who specializes in cancer and its diagnosis. This doctor will examine the cells under a microscope to check for any abnormalities that might indicate cancer. In some cases, the first biopsy will remove fluid from around the lungs or from the abdomen. The pathologist will examine the cells found in this fluid for signs of cancer; however, many physicians consider this test insufficient for mesothelioma diagnosis.

X-rays:

Chest or abdomen x-rays can reveal fluid build-up, masses in the chest, or signs of non-cancerous pleural disease, scarring of the lungs and areas of fluid accumulation. Based on a patient’s x-ray results, a doctor will usually order more sensitive tests.

Computerized Tomography (CT) scans:

A CT scan is a series of detailed pictures of areas inside the body created by a computer linked to an x-ray machine. A computerized axial tomography (CAT or CT) scan produces a cross-sectional image of the parts of your body that your doctor wants to study, such as the chest and abdomen. An x-ray source rotates around your body sending data to a computer. A CAT scan helps your doctor determine how large any tumors are, where they are in relation to the heart, lungs and diaphragm, if there is pleural thickening, and how much fluid there is. A CAT scan also helps your doctor determine what stage your cancer is in.

The computer then analyzes the data and produces a series of images. CT scans are also able to define pleural effusion, as well as pleural thickening, pleural calcification, thickening of interlobular fissures, or possible chest wall invasion. CT scans cannot differentiate between benign or malignant mesothelioma. CT scans may also be valuable in guiding fine needle aspiration of pleural masses for tissue diagnosis.

Positron Emission Tomography (PET) scans:

PET imaging tests have become one of the most efficient ways of diagnosing mesothelioma tumors as well as determining the staging of the cancer. In a positron emission tomography (PET) scan, abnormal areas show up as bright spots. These bright spots may or may not be cancer, so not all doctors believe that these scans are helpful in trying to diagnose mesothelioma cancer. If you have mesothelioma cancer, a PET scan can show whether the cancer has spread outside the area of the body in which it originated (whether it has metastasized).

While PET scans are more expensive than other types of imaging, and are not always covered under insurance, they are now considered to be the most diagnostic of tumor sites, as well as the most superior in determining the staging of mesothelioma.

MRI scans:

Magnetic resonance imaging (MRI) is a type of scan that uses a magnetic field linked to a computer to create an image of the internal structures of your body. An MRI uses powerful magnets and radio waves to produce a detailed, three-dimensional view of the areas where mesothelioma is suspected.

MRI scans use a computer-linked magnet to photograph details of the inside of the body and can determine the severity of a tumor. MRI scans are most often used to determine the extent of tumor prior to aggressive treatment. Because they provide images in multiple planes, they are better able to identify tumors as opposed to normal structures. Sometimes, an MRI can show whether a tumor has invaded the diaphragm or chest wall.

They are also more accurate than CT scans in assessing enlargement of the mediastinal lymph nodes (those lymph nodes which lie between the two lungs), as well as a clear diaphragmatic surface, both of which play an important role in surgical candidacy.

Continued from Diagnosis of Mesothelioma: Part – 1

The physical exam should involve a number of imaging tests to search for suspicious cell formation. These typically diagnostic tests include medical imaging scans such as:

Blood tests:

Blood tests are not specifically for mesothelioma. Blood tests will be performed to check white blood cells (WBC) count and platelet count. White blood cells fight infection and platelets are blood cells that help the blood clot.

A new and promising method to detect mesothelioma is MESOMARK assay. This is a blood test used to detect peptides released into the blood stream by mesothelioma cells. Mesothelioma patients usually have an elevated MRP in their blood stream years before actual diagnosis is made. This test is only FDA approved for humanitarian use. It only used to follow someone already diagnosed with mesothelioma (of an epitheloid type) to give an indication of whether or not the cancer is growing.

Some specific substances present in the blood which act as biomarkers, by using one or more biomarkers, a blood test can detect mesothelioma.

Osteopontin, a protein in the liquid part of the blood, is also being investigated as a biomarker for asbestos. In October 2005, The New England Journal of Medicine reported a study showing that persons who have been exposed to asbestos and have pleural mesothelioma, in those patients level of osteopontin is different than in those who have been exposed to asbestos but who do not have cancer.

Mesothelioma is not always diagnosed because the cancer is still unrecognizable. A mesothelioma diagnosis may often be classified as another condition because the symptoms are similar to those of other illnesses. Mesothelioma’s symptoms are not unique and the disease’s relative rarity, cases of mesothelioma misdiagnosed are not uncommon.

Medical history:

Diagnosis begins with a review of the patient’s medical history. The first step involved in diagnosis is providing a full and accurate medical history to your doctor, including details about current and past health concerns, as well as the types of symptoms and signs signs including shortness of breath, chest pains, swollen abdomen, and more you are currently experiencing.

It is important to mention any possible exposure to asbestos. Without revealing this fact, your doctor may not consider asbestos-related diseases in his or her examination. Mesothelioma patients are typically diagnosed within three to six months of their first visit to a doctor with complaints about breathing problems or chest and abdominal pain.

One of the most common carcinogen asbestos develops mesothelioma. Asbestos acts as a carcinogen in the growth of both pleural and peritoneal mesothelioma which occurs in subsiquent stages of triggering and growth. Asbestos fibres are thought to exert their carcinogenic effects via direct physical interactions with the cells of the mesothelium in conjunction with indirect effects following interaction with inflammatory cells such as macrophages.

Asbestos has also been shown to aid the entry of foreign DNA into healthy cells. This foreign DNA can insert itself into the human genome, causing mutations by one of the following mechanisms:

• Activation of oncogenes
• Activation of proto-oncogenes due to incorporation of foreign DNA containing a promoter region
• Prevention of apoptosis
• Inactivation of tumor suppressor genes
• Activation of DNA repair enzymes

Different types of asbestos fibers were studied in rats and mice, showed that long, thin fibres caused a higher incidence of mesothelioma than did short fibres and that cells will actually phagocytose longer fibres more effectively than shorter fibres. Interactive analysis between asbestos fibres and DNA has shown that phagocytosed fibres are able to make contact with chromosomes, often adhering to the chromatin fibres or gets entangled within the chromosome. This direct contact between the asbestos fibre and the chromosomes or structural proteins of the spindle apparatus can induce complex abnormalities. The most common abnormality is monosomy of chromosome 22. Other frequent abnormalities include structural rearrangement of 1p, 3p, 9p and 6q chromosome arms. Common gene abnormalities in pleural and peritoneal mesothelioma cell lines include deletion of the tumor suppressor genes.

Following asbestos phagocytosis, macrophages generate increased amounts of hydroxyl radicals. However, these free radicals are also known clastogenic and membrane-active agents thought to promote asbestos carcinogenicity. These oxidants can participate in the oncogenic process by directly and indirectly interacting with DNA, modifying membrane-associated cellular events, including oncogene activation and perturbation of cellular antioxidant defences. Asbestos also may possess immunosuppressive properties.