Early symptoms of mesothelioma are non-specific in nature, and may lead to a delay in diagnosis. In general, shortness of breath, chest pain and persistent cough are common symptoms of pleural mesothelioma, but in some cases, may not be severe enough to force the patient to seek medical help. Some patients complain of pain in the shoulder blade or lower back. These symptoms most often occur 2-3 months prior to a confirmed diagnosis. In peritoneal mesothelioma, abdominal pain and swelling, nausea or vomiting, bowel obstruction and weight loss are the most common symptoms. Importantly, these symptoms are not unique to mesothelioma, and may be symptoms of other conditions as well. Evaluation by a qualified physician is always suggested.

As mesothelioma progresses, pleural effusion (fluid build up between the two pleural layers) occurs in 95% of patients, and it is this symptom which ultimately leads to patients visiting their GP. During this visit, a chest x-ray is taken which may confirm the effusion. A thickening of the pleura may also be noted at this time. If the GP suspects cancer is a possibility, referral may be made to a hospital consultant who specializes in lung cancer and mesothelioma.

When your GP recommends a referral, you should be given the following information:

Where you are being referred.
When the appointment will be scheduled.
Who you will see.
What testing you can expect.
When the results of the testing will be available.

The National Institute for Health and Clinical Excellence has developed the following general referral guidelines for suspected cancer, effective June, 2005. These guidelines may not apply to every individual, and you should always discuss the details of your specific case with your health care team, so you can play a proactive role in your treatment and care.

An assessment of urgency will be made by your GP, and will be based on the following criteria:

Immediate referral: The patient needs to be seen within a few hours.
Urgent referral: The patient will be seen within two weeks.
Non-urgent: All other referrals.
Once urgency is determined, your GP will send all information pertaining to your case to your specialist for evaluation.
Diagnosis

A diagnosis of mesothelioma is most often obtained with a careful assessment of clinical and radiological findings in addition to a confirming tissue biopsy. Following are some of the tests your specialist may recommend and their value in diagnosing and assessing mesothelioma.

CT scans are able to define pleural effusion, as well as pleural thickening, pleural calcification, thickening of interlobular fissures or possible chest wall invasion. CT, however, is not able to differentiate between changes associated with benign asbestos disease, or differentiate between adenocarcinoma of the lung versus mesothelioma. CT scans may also be of value in guiding fine needle aspiration of pleural masses for tissue diagnosis. This scan usually takes 10-30 minutes, but may vary according to the patient.

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. They are also more accurate than CT scans in assessing enlargement of the mediastinal 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. An MRI scan usually takes 20-40 minutes, but may vary according to the patient.

PET imaging is now becoming an important part of the diagnosis and evaluation of mesothelioma. PETs are considered to be the most diagnostic of tumor sites, as well as the most superior in determining the staging of mesothelioma. Because PET scans are relatively new and may not be available in all locations, it may be necessary to travel to a specialized center to have one.

Testing of the pleural fluid for malignant cells is considered to have limited value in diagnosing mesothelioma. Diagnostic thoracentesis, in which cells are extracted from the pleural cavity, is commonly done when the possibility of mesothelioma exists. Unfortunately, negative or inconclusive readings account for nearly 85% of all fluid tested. Even in the event of a positive fluid report, doctors may opt to perform a confirming tissue biopsy as long as it is not detrimental to the patient's health.

In most cases, it is ultimately a needle biopsy of the pleura, or an open surgical biopsy, that yields a confirmed diagnosis of mesothelioma. In a pleural biopsy procedure, the surgeon will make a small incision through the chest wall and insert a thin, lighted tube called a thorascope into the chest between two ribs. He will then remove a sample of tissue to be reviewed under a microscope by a pathologist. In a peritoneal biopsy, the surgeon makes a small incision in the abdomen and inserts a peritoneoscope into the abdominal cavity.

Knowing the stage of your mesothelioma will be a factor in helping your doctor formulate a treatment plan. The most definitive and most widely used system is the TNM International Staging System for Diffuse Malignant Pleural Mesothelioma, also called the International Mesothelioma Interest Group System. This system takes into consideration Primary Tumor (T), Lymph Nodes (N) and Metastases (M). There is no established staging system for peritoneal mesothelioma. Peritoneal patients may be staged according to the general TNM system for cancer, or on the bulk of the tumor present (i.e., minimally bulky, moderately bulky, etc.). Because the TNM system is very in depth, and difficult for interpretation by lay persons, following is a simplified version. Stage I is the earliest stage; Stage IV the most advanced.

Mesothelioma involves the right or left pleura and may also have spread to the lung, pericardium or diaphragm on the same side. Lymph nodes are not involved.

Mesothelioma has spread from the pleura on one side to nearby lymph nodes next to the lung on the same side. It may also have spread into the lung, pericardium or diaphragm on the same side.

Mesothelioma has invaded the chest wall, muscle, ribs, heart, esophagus or other organs in the chest on the same side with or without spread to lymph nodes on the same side as the primary tumor.

Mesothelioma has spread into the lymph nodes in the chest on the side opposite the primary tumor, or extends to the pleura or lung on the opposite side or directly extends into organs in the abdominal cavity or neck. Any distant metastases in included in this stage.