Straight Talk about Mesothelioma, a blog series created by Michael T. Milano, M.D., Ph.D., a radiation oncology specialist, as a resource for mesothelioma patients and their loved ones.
One major obstacle that physicians face when making the initial diagnosis of mesothelioma is the cancer’s long latency period between exposure to asbestos and development of symptoms. Simply put: It can take decades for the cancer to present itself. The doctor’s very first step in making a diagnosis of mesothelioma is to obtain a patient’s history of asbestos exposure.
Exposure to asbestos can come in a variety of different ways, whether the exposure occurred through a person’s work in such trades as shipbuilding, construction, manufacturing, pipefitting, or demolition, or through secondary exposure that occurred after a loved one or family member washed the garments of someone who worked had been exposed. Once the patient’s history is taken and a physical exam is performed, the next step would be for the doctor to make a definitive diagnosis.
What Type of Tests Are Done to Make a Diagnosis of Mesothelioma?
Because the symptoms and signs of mesothelioma are what doctors call “non-specific,” some type of testing is always required. A mesothelioma diagnosis cannot be obtained from blood work.
The first test a doctor typically orders is usually a chest x-ray which may reveal the presence of fluid or a mass in the chest cavity. Unfortunately, a plain x-ray is not sensitive enough for detection of most pleural lesion(s). Only in advanced cases will a chest x-ray show fluid in the chest cavity, thickening of the pleura, or a mass in the lung.
A CT scan of the chest is usually done after a chest x-ray. Compared to an x-ray, a CT scan is much more sensitive. The CT scan can produce images of small lesions and fluid collections, and in some cases, can detect the spread of cancer to other organs like the heart lining (pericardium) or diaphragm. Based on the findings of the CT scan, the next step in a diagnosis is a biopsy. A biopsy is necessary, because there is no way of knowing what the lesion is simply by looking at it on a CT scan. Doctors will need to perform a biopsy to have a closer and more thorough examination.
What about the Fluid in the Chest?
Patients with mesothelioma almost always have fluid collection in their chest cavities. This fluid can easily be removed with a small needle under local anesthesia and then sent to the laboratory for analysis. Unfortunately, however, in most cases, the fluid rarely reveals presence of mesothelioma.
That said, newer markers for mesothelioma are being developed to check the fluid for mesothelioma cells, but these tests are still in the early developmental stages and not routinely used currently. It’s important to remember that just because the pleural fluid does not show the presence of mesothelioma cells, it doesn’t mean that the patient doesn’t have this kind of cancer.
How Is a Biopsy Done in a Patient’s Pleura?
There are several ways to perform a pleural biopsy and it depends on where in the chest the mass is located. In most cases, a CT guided biopsy is performed first. The procedure is done in the radiology suite by an interventional radiologist. A local anesthetic is given, and the needle is directed towards the pleural mass under CT guided vision. The procedure rarely takes more than an hour, after which the tissue is sent to a pathologist to examine under a microscope.
If the lesion is in an area where it cannot be accessed by the radiologist, a surgeon may consulted to perform a biopsy using a video-assisted procedure. This requires general anesthesia and an overnight stay in the hospital. During the procedure, a tiny camera is inserted in the chest cavity and, using special instruments, the lesion can be biopsied. The procedure also allows the surgeon to see if the cancer has spread to any other parts of the body.
What Happens to the Tissue?
The biopsied tissue is then analyzed under the microscope by a pathologist. The results usually take 7-14 days to confirm the diagnosis. The reason for the delay is that in some cases, mesothelioma can easily be mistaken for other lung cancers. Because not all hospitals are familiar with mesothelioma, sometimes the biopsy specimen has to be sent to a specialized cancer center where experts can look at it and make a firm decision. Doctors have to make certain that the cancer being tested is mesothelioma before they can recommend any kind of treatment regimen. Microscopically, there are 3 cell types of mesothelioma: namely epithelial, sarcomatous, and mixed. The epithelial type carries the best prognosis.
What Is Staging?
Once it is confirmed that a patient has pleural mesothelioma, all patients will undergo what is known as “staging.” Staging tells the doctor how big the tumor is, how far it has spread, and if it involves any other organs. Even though the optimal staging procedures are debatable, in most cases, the patient will undergo a refined CT scan, MRI, PET scan, and a bone scan before a stage is determined. These imaging tests will reveal the exact location, size, and any potential spread of the cancer. In some rare cases, staging may involve looking inside the chest with a video camera. Staging is done before any treatment, as the staging help determines the treatment options.
If a patient has an early stage cancer, (usually stage 0 or 1), and is reasonably fit, then surgery is recommended so that the patient has the best chance of being “cured.” However, if a patient has an advanced stage cancer, then surgery might not be the best option, and a patient may be offered palliative chemotherapy and/or radiation. As always, it’s best that a patient consult his or her doctor before requesting any specific medical treatment or procedure.