Asbestos is a natural mineral widely used in construction, shipbuilding and manufacturing for nearly 100 years before being established as toxic. The National Institutes of Health (NIH) estimates that only between 1940 and 1978 about 11 million people were exposed to the material, which is responsible for the development of mesothelioma, lung cancer, asbestosis, and other conditions. Mesothelioma is an aggressive type of cancer, which is usually developed 20 to 50 years after exposure, and can attack the tissue linings of the lungs, abdomen, heart or testicles.
Like all cancers, there are different stages of mesothelioma, a system used by physicians to describe how advanced the disease is, how prevalent the tumors are, and how far the cancer has spread. Staging is key to defining proper diagnosis, including exactly where the cancer is and its development, as well as to define a treatment plan and the options that are still or no longer available. There are three systems to determine the stage of pleural mesothelioma, the most common type, while the stages vary from I to IV, depending of factors like size and location of the tumor, and whether it has or not spread to the lymph nodes or distant organs.
Four Progressive Stages of Mesothelioma
Stage One Mesothelioma
Stage one mesothelioma is classified when the disease is at its earliest phase of development. During this stage, tumors are located near the original site of disease, and have only grown in one layer of the lungs’ lining, which is known as the pleura. Life expectancy for patients who are diagnosed with stage I mesothelioma is usually better than in later stages, with the average being more than three years from time of diagnosis. However, patients are almost never diagnosed at this stage, since symptoms are almost imperceptible. Symptoms of mesothelioma tend to be noticed only in later stages, while they can also be mistaken by other lung disorders. The first course of treatment is usually curative surgery to resect the tumor, which can be combined with chemotherapy and radiotherapy.
Stage Two Mesothelioma
Stage II is still considered an early phase of mesothelioma, during which the symptoms are vague and mild. During this time, patients start to lose weight and feel bloated, but it can still be mistaken as a flu or other disease. However, the diagnosis is slightly more common than stage I. There are several treatment options, with surgery being the first line of treatment. Patients diagnosed at stage II of mesothelioma can live for years, but the median life expectancy is 19 months.
Stage Three Mesothelioma
When mesothelioma has progressed to stage III, it has already considered to be in an advanced stage and it is likely to have spread to other locations on the same side where the cancer first developed. Lymph nodes, the esophagus, muscles, ribs, heart and the chest wall are common places for cancer spreading. Stage III mesothelioma patients start to experience more difficulty breathing and intense chest pain even at rest, while bowel obstruction and pain can also occur. Since mesothelioma has spread to various locations at this stage, patients may feel discomfort in other body parts. During this phase, surgery may no longer be an option, while chemotherapy and radiation therapy are more common. Physicians may also start considering palliative care. Stage III mesothelioma patients have a median life expectancy of 16 months.
Stage Four Mesothelioma
In patients with stage IV mesothelioma, cancer has metastasized throughout the all body through the bloodstream. Symptoms are more severe and can include difficulty breathing and severe chest pain. When there are tumors in the esophagus or stomach, patients can also experience digestive problems and difficulty swallowing or eating. Given the aggressiveness of the disease at this stage, surgery is no longer recommended and the majority of the patients undergo palliative care to help ease the pain and other symptoms. However, about 30 percent of all patients are only diagnosed when they are already at stage IV mesothelioma, which has an average life expectancy of less than 12 months.
Specific Staging Systems for Each Mesothelioma Type
Pleural mesothelioma, which develops in the lining of the lungs or pleura, is the most common type of the disease, accounting for about 75 percent of all cases. Therefore, there are three different systems used for pleural mesothelioma staging. They are slightly different but all have four stages. The Butchart Staging System is the oldest and most common one. This system focuses on the primary location of the cancer and advances as it spreads throughout the body. However, the Butchart staging system excludes the number of cancer cells present, the size of the tumor and percentage of body affected by the cancer.
The TNM Staging System was developed by the American Joint Committee on Cancer (AJCC) and it is used not only for mesothelioma, but for a series of cancers. The most updated version of it was published at the AJCC Cancer Staging Manual (7th ed., 2009) and includes characteristics of the tumor (T), involvement of the lymph nodes (N), and metastasis (M). In addition, Brigham Staging System also has four stages and the main different is that it includes as well the assessment of surgical efficacy at each stage.
There are four different types of mesothelioma, including peritoneal, pericardial and testicular, in addition to pleural mesothelioma. While mesothelioma is already an uncommon disease, the peritoneal, pericardial and testicular forms are particularly rare, which is why no staging systems have been established for them. Therefore, physicians are recommended to use the general guidelines from the AJCC Cancer Staging Manual. Despite not being specific to any type of cancer, these guidelines can help determine the stages of extremely rare cancers like these ones.
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