Staging Mesothelioma Cancer
The staging of mesothelioma is an important part of an overall diagnosis. The stage describes the progression of any type of cancer, and it may range from stage I through stage IV with the latter being the most advanced and most difficult to treat. Anyone with symptoms characteristic of mesothelioma, and especially those with a history of asbestos exposure needs to get an accurate diagnosis with staging as early as possible.
Both an accurate diagnosis and an accurate description of the stage of mesothelioma are crucial for giving a patient the best treatment plan. Doctors use the stage, and whether or not the original tumor has metastasized or spread to other tissues, to plan the best course of treatment. Without this crucial information, treatment is not likely to be beneficial or to produce the best outcomes. Staging is especially important for mesothelioma because this is a fast-spreading, aggressive cancer.
What Is Staging?
Staging is the process of figuring out where cancer is in a patient’s body, how much cancer is there, and how much it has spread from the location of the original tumor. The result of staging is the stage of the cancer. Stage does not change, even as the cancer grows and spreads, or shrinks with treatment. The stage determined with the original diagnosis remains constant, although to it may be added descriptions.
This is hard to understand, but it is a consistent approach that doctors use to describe cancer in patients. As an example, a patient has been diagnosed with stage II mesothelioma, and a few months later it has been determined that the cancer spread to the lymph nodes. This patient would now be described as having stage II mesothelioma with lymph node metastasis, rather than changing the stage to III or IV.
The Importance of Staging
The staging of mesothelioma can be thought of as a more detailed investigation or diagnosis of cancer in an individual. It gives all members of a medical team the information about where and how the cancer has spread in a patient. It is a way of communicating this important information. The stage also gives a doctor and medical team a better idea of how to proceed with treatment. For instance, stage IV cancers are nearly impossible to treat with surgery while a stage I cancer may be cured through surgery.
The stage also provides a standpoint from which to estimate the prognosis for a patient. Through data collected from patients treated for different types of cancer, doctors get a good picture of about how long a patient will survive the diagnosis of mesothelioma and other cancers at each stage. The staging also helps researchers to group study participants together to make sure patients receiving novel treatments are at a similar stage.
Factors Used in Staging
The process of staging any cancer, including mesothelioma, involves examining a patient using various diagnostic techniques. Doctors and specialists use imaging scans of the patient’s body as well as examination of biopsied tissue samples to describe several features of the cancer that can then be used to stage it:
- The location of the original tumor and any other tumors.
- The cell type, such as sarcomatoid or epilthelioid.
- The size of the tumor or tumors.
- If the cancer cells have spread to the lymph nodes.
- If the cancer cells have spread to another part of the body.
- The tumor grade, which is a description of the extent of abnormal qualities of its cells.
TNM Staging System
In order to communicate information about a patient’s cancer from one medical professional to another, it is important that cancers are staged according to set guidelines. There are multiple systems and guidelines used for staging, but the TNM system is the most widely used, including for mesothelioma.
The TNM system uses three main factors for describing the stage. The T stands for tumor and refers to the primary tumor. N stands for nodes and is a description of the extent to which the cancer has spread to the lymph nodes. M stands for metastasis and describes the extent to which the original tumor has spread and invaded other tissues or organs in the body.
Under each category a person with a mesothelioma diagnosis will be given a letter and number designation. These are then taken together to determine whether the cancer is at stage I, II, III, or IV. Sometimes a stage of 0 is used as well. Stage 0 refers to carcinoma in situ, which means that abnormal cells have been found, but they have not spread yet. They are not yet considered cancer, but have the potential to become cancer.
The T designation in staging mesothelioma describes the original tumor:
- TX means the tumor could not be assessed.
- T0 is no evidence of a primary tumor.
- T1 is a primary tumor in the pleura on just one side of the chest and possibly along the diaphragm.
- T2 is a primary tumor found in the pleura on one side of the chest, but also on the pleura lining the diaphragm and the lung. It has spread into either the diaphragm or the lung.
- T3 is a primary tumor that includes every location in T2 and has also either invaded the chest wall, fatty tissues, or the pericardium.
- T4 is a primary tumor that has invaded even further, into the esophagus, trachea, thymus, spine, or to the pleura on the other side of the chest.
The N factor describes the extent to which the cancer has invaded the lymph nodes:
- NX means the lymph nodes couldn’t be examined.
- N0 means there has been no spread to the nodes.
- N1 means that the cancer has spread to lymph nodes within or near the lung on the same side as the primary tumor.
- N2 means the cancer has spread to lymph nodes farther out, but on the same side of the chest as the primary tumor.
- N3 means it has spread to nodes on either side of the chest.
The M description states whether or not the original cancer has spread to other areas of the body, significantly far from the primary tumor. There are just two designations for M. M0 means that there has been no metastasis and M1 means that there has been metastasis, or spread of the cancer to distant parts of the body. Once the TNM factors have been determined for a patient with mesothelioma, these are combined to give a stage.
Stage I Mesothelioma
A combination of T1, N0, and M0 is considered stage I mesothelioma. This stage of mesothelioma describes a cancer in which the tumors are only in the pleura. There has been no spread to the lymph nodes and no metastasis. Life expectancy for stage I mesothelioma is longer than for the other stages, but unfortunately most people are diagnosed after the cancer has passed this stage. Stage I mesothelioma does not usually cause symptoms severe enough to lead to a diagnosis. If it is caught this early, aggressive treatment with surgery, chemotherapy, and radiation is typical.
Stage II Mesothelioma
A combination of T2, N0, and M0 is considered to be stage II mesothelioma. At this stage a patient may have some spread of the primary tumor, but it has still not metastasized or invaded the lymph nodes. Symptoms at stage II are still pretty mild and may be mistaken for other conditions. Treatment at this stage is similar to stage I. The survival rate for stage II mesothelioma is about 19 months.
Stage III Mesothelioma
Stage III mesothelioma may be a combination of T1 or T2, N1 or N2, and M0. It may also be T3, N0 through N2, and M0. By stage III the cancer has spread to various parts of the pleura and other tissues close to the original tumor. It may also have spread to nearby lymph nodes. There are more symptoms at this stage, including significant breathing difficulties and chest pains. Surgery may or may not be an option as treatment at stage III.
Stage IV Mesothelioma
A combination of any T designation with N3 and M0 is considered stage IV mesothelioma, as is a combination of any T, any N, and M1. Many patients with mesothelioma are not diagnosed until the cancer has reached stage IV. At this point it may have spread throughout the chest cavity, on either side of the body, and it has either extensively invaded the lymph nodes or it has metastasized. People at this stage are not expected to live longer than a year and most cannot be treated surgically. Chemotherapy, radiation, and palliative treatments may extend life and make the patient feel more comfortable.
Resectable, Unresectable, and Metastatic Mesothelioma
There are other ways to categorize mesothelioma that are broader and less detailed than staging. For instance, a cancer may be categorized as metastatic if it has been seen to have spread to distant parts of the body from the primary tumor. This is essentially another way of saying that the cancer is stage IV.
Mesothelioma may also be described as resectable or unresectable. This refers to whether or not the cancer is operable. In most stage I, II, and III mesothelioma patients, surgery is an option to try to remove all or some of the tumor. In other words, these cases are resectable. If surgery is not an option, usually because the cancer has metastasized, it is categorized as unresectable.
Tumor Grading and Other Factors
In addition to the descriptions of T, N, and M, other factors may be considered and used to describe mesothelioma. These may or may not affect the assigning of a stage. One additional factor is tumor grade. The grade describes how abnormal the cells of the tumor appear when inspected under a microscope. The more abnormal the cells the more likely the cancer is to grow and spread quickly. Grade is usually given as a number from one to three.
Cell type is another consideration, and is also determined by looking at the cancer cells under a microscope. The cells may be described as sarcomatoid, epithelioid, or biphasic, a mixture of the other two types. This helps with staging, treatment, and prognosis, because cell type impacts how a cancer grows and spreads.
Alternative Staging Systems
Most doctors currently use the TNM system to stage mesothelioma, but there are some alternatives, including the Butchart system. This is an older system for mesothelioma and it was designed to identify patients that were good candidates for aggressive and curative treatment. It also uses designations of stage I through IV. The Brigham system is another staging system, also using the designations I through IV.
The staging of mesothelioma is a crucial part of diagnosing it completely, as is determining whether or not the cancer has metastasized. The description of stage helps medical teams figure out what the best treatments are for a particular patient and gives that patient an estimated outlook for the future and how helpful the treatments are likely to be. If you have been diagnosed with mesothelioma, be sure that you get a thorough assessment of the stage and seek a second opinion if you are not satisfied.
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