Mesothelioma staging

The treatment and outlook for those with mesothelioma depends a great deal on the stage of their cancer. Because the most frequently occurring type of mesothelioma is pleural, and it is also the one most studied, it is the only type for which a mesothelioma staging system exists. The following stages are based on a system known as the Butchart system, which divides mesothelioma into four stages: Another system of mesothelioma staging mesothelioma is based on a TNM system (T=tumor, N=spread to lymph nodes, and M=metastasis). There are minor differences between this and the Butchart system. It is more detailed and precise, but the original Butchart system is still the one most often used to describe pleural mesotheliomas.

The oldest mesothelioma staging system and the one most often used is the Butchart System which is based mainly on the extent of primary tumor mass and divides mesotheliomas into four stages. The more recent TNM system considers variables of tumor in mass and spread, lymph node involvement, and metastasis. The Brigham System is the latest system and stages mesothelioma according to resectability (the ability to surgically remove) and lymph node involvement.

X-rays, CT scans, and MRIs - See the imaging section for more on these techniques. On conventional x-ray film, mesothelioma appears as a markedly thickened, nodular, irregular pleural-based mass which covers the pleural surface. The tumor often encompasses the involved lung, but is only rarely seen bilaterally. Chest wall, diaphragmatic, and mediastinal invasion may be seen in advanced cases. Moderate to large pleural effusion is often noted on the affected side. On CT scan, pleural thickening greater than 1 cm can be identified in over 90% of cases; thickening which extends into the interlobular fissure is seen in 85% of cases. Absence of pleural thickening does not preclude mesothelioma, and at times, the only CT finding is that of pleural effusion.

Cytology - Testing of the pleural fluid for malignant cells is considered to have limited value in diagnosing mesothelioma. Negative or inconclusive readings account for nearly 85% of all fluid tested. Even with a positive fluid report, many doctors prefer to perform a confirming tissue biopsy as long as it does not compromise the patient's health.

Needle Biopsy - In this test, done under local anesthetic, a large hollow needle is inserted through the skin and into the chest cavity. The needle is then rotated, and as it is taken out, tissue samples are collected. Because of the small sample size of the tissue, this type of biopsy is considered to be only 25-60% accurate in diagnosing mesothelioma. Because tumor seeding may occur along the needle tract in approximately 20% of patients, local radiation therapy may be used in conjunction with this test.

Open biopsy - This type of biopsy is considered to be the most accurate for mesothelioma diagnosis, and is the procedure of choice because it affords the pathologist a larger tissue sample.. It is done in a hospital under general anesthetic. As with a needle biopsy, local radiation may be used because of the possibility of tumor seeding.

Mesothelioma Stages

Treatment options are often determined by the stage of mesothelioma a patient is in.

TNM System -- variables of T (tumor), N (lymph nodes), M (metastasis) Stage I: Mesothelioma involves right or left pleura and may also have spread to the lung, pericardium, or diaphragm on the same side. Lymph nodes are not involved.

Stage II: 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.

Stage III: Mesothelioma is now in 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.

Stage IV: 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 is included in this stage.

Mesothelioma staging the Disease

Stage I: Disease confined within the capsule of the parietal pleura, lung, pericardium, and diaphragm Stage II: All of stage I with positive (N1 or N2) lymph nodes Stage III: Local extension of disease into chest wall or mediastinum, heart or through the diaphragm, peritoneum; with or without extrathoracic or contralateral (N3) lymph node involvement Stage IV: Distant spread of disease or metastasis