Staging is important, but what does it mean? The process of staging describes the disease’s status at a specific moment in time. An evaluation of the stage of cancer involves assessing the characteristics of the tumor (T), whether cancer has spread to lymph nodes (N), as well as metastasis, which is the spread of cancer to other parts of the body (M).
As well as giving the physician an idea of the prognosis of a patient, staging is critical for helping them choose the appropriate treatment plan. Due to the diffuse nature of mesothelioma, standardizing a global staging system is difficult, since there are very few cases on which to base it.
There are staging systems developed by Brigham and Women’s Hospital in Boston and the International Mesothelioma Interest Group (IMIG). Despite their similarities, the two are slightly different. It does not matter which system is used as long as the results for T, N, and M components are reported consistently and accurately.
In fact, the International Association for the Study of Lung Cancer (IASLC) will be revising the staging system in 2009 or 2010 with help from worldwide institutions that treat mesothelioma patients. The staging system for mesothelioma consists of four stages as with many other kinds of cancer.
A person with cancer in Stage 1 has a very good prognosis, whereas a person with cancer in Stage 4 has the worst prognosis. The prognosis is the worst at this stage. T, N, and M stages are further subdivided according to the staging system. Cancer is classified into T stages based on their size and whether they are associated with nearby critical structures.
A lymph node examination is conducted during the N stage in order to determine whether cancer has spread to other lymph nodes inside or outside the lungs. Cancer that has metastasized (spread to other parts of the body) is considered to be in the M stage.
What is Staging in Mesothelioma? Photo Credit – Healthline
Mesothelioma staging guidelines: what are they?
Mesothelioma doesn’t have a single dominant mass like lung cancer. Mesothelioma affects multiple surfaces, has different thicknesses, and makes it difficult to determine if lymph nodes are involved from the radiographic image. It is extremely difficult to stage mesothelioma based on x-rays and symptoms alone.
Unless a thoracoscopy is performed on an early-stage patient, even experts find it difficult to determine whether they have Stage I or Stage II mesothelioma. A Stage III case is one where the disease has spread to the lymph nodes, despite the fact that it is presumed to be in the early stages. A patient’s life expectancy depends on the involvement of the lymph nodes in both staging systems.
Furthermore, IMIG uses a staging system that looks at whether adjacent structures have been affected by the disease, rather than just those that are “sitting on” or “touching” the disease. In addition to PET scans, which have been mentioned earlier, groups in the United States and Europe use clinical and laboratory parameters to assist with staging. To determine the true stage of the disease, some centers are even trying to measure the volume of the disease.
The bottom line?
These descriptors can only be accurately staged by performing an operation to identify these invasive features and the extent of the disease, and taking samples from or removing the lymph nodes for examination. It is only through “surgical staging” that a definitive stage can be determined in a patient, but not all mesothelioma patients should have an operation.
In the future, the “Holy Grail” of mesothelioma staging will be when we can simply analyze the genes or proteins in the original biopsy specimen. And tell the patients what their prognosis is and how they will progress (that is, what their “molecular stage” is) based on these findings. Ultimately, the goal in this situation will be to guide treatment based on these molecular observations.
