Key Takeaways
- Mesothelioma tumor severity is determined by more than tumor size. Doctors also consider how far the cancer has grown, whether lymph nodes are involved, and whether it has spread to distant parts of the body.
- The TNM staging system measures pleural mesothelioma by evaluating the primary tumor, nearby lymph nodes, and distant metastasis.
- CT scans, PET scans, MRI, and biopsies can help doctors determine the location and extent of mesothelioma.
- Tumor location matters because mesothelioma that has invaded nearby structures may be more difficult to remove with surgery.
- The type of mesothelioma cells, overall health, treatment response, and whether surgery is possible can also affect prognosis and treatment decisions.
- Understanding mesothelioma tumor severity helps doctors develop an individualized treatment plan based on how far the disease has progressed.
Mesothelioma tumor severity is not determined by tumor size alone. Doctors look at how far the cancer has grown, whether nearby lymph nodes are affected, whether it has spread to distant parts of the body, and whether the tumor can potentially be removed with surgery. These findings help doctors determine the stage of pleural mesothelioma and develop an appropriate treatment plan.
Understanding mesothelioma tumor severity can help patients and families understand why doctors order multiple tests and why treatment recommendations can differ from one patient to another.
What Does Mesothelioma Tumor Severity Mean?
When doctors discuss tumor severity, they are describing the extent of the cancer rather than simply how large one tumor appears.
Pleural mesothelioma can spread along the pleura, the thin lining surrounding the lungs and inside of the chest wall. Because of this pattern, measuring the disease can be more complicated than measuring a single mass.
Doctors consider several questions:
- How far has the primary tumor grown?
- Has the cancer invaded nearby structures?
- Have lymph nodes been affected?
- Has the cancer spread to distant organs?
- Can the tumor potentially be removed with surgery?
- What type of mesothelioma cells are present?
Together, these findings provide a clearer picture of the disease.
How Mesothelioma Staging Measures Tumor Severity
For pleural mesothelioma, doctors primarily use the TNM staging system.
TNM stands for:
- T — Tumor: How far the primary tumor has grown
- N — Nodes: Whether nearby lymph nodes contain cancer
- M — Metastasis: Whether the cancer has spread to distant parts of the body
Doctors combine the T, N, and M classifications to assign an overall stage from I through IV. Generally, a higher stage means the cancer has spread farther or is more extensive.
The formal TNM staging system applies to pleural mesothelioma. Peritoneal and pericardial mesotheliomas do not have the same formal TNM staging system, although doctors still evaluate how extensively those cancers have spread.
How Doctors Measure the Primary Tumor
The T category describes how far the primary pleural mesothelioma has grown.
Doctors evaluate which areas of the pleura contain cancer and whether the disease has grown into nearby structures.
Modern staging also considers the thickness of pleural tumor measured at specific locations on imaging. This measurement, known as the Psum, can help distinguish between different T categories.
The location of the tumor is also important.
Mesothelioma that has invaded structures such as the diaphragm, lung tissue, chest wall, mediastinal tissues, or other nearby areas may represent more advanced local disease.
This means two patients with tumors that appear similar in size could have different levels of mesothelioma tumor severity depending on where the cancer has grown.
How Lymph Nodes Affect Mesothelioma Tumor Severity
The N category describes whether mesothelioma has spread to regional lymph nodes.
Lymph nodes are part of the body’s immune system and can become involved when cancer cells travel away from the primary tumor.
For pleural mesothelioma, doctors consider both the presence and location of lymph-node involvement.
Cancer limited to the original area with no regional lymph-node involvement generally represents less extensive disease than cancer that has spread to regional nodes.
Lymph-node involvement can therefore change the overall stage and may affect whether surgery or other treatments are appropriate.
How Metastasis Affects Tumor Severity
The M category describes distant metastasis.
Metastasis occurs when cancer spreads from its original location to distant parts of the body.
Advanced pleural mesothelioma can spread to areas such as the opposite side of the chest, bones, liver, peritoneum, or other distant structures. Distant metastatic disease is classified as M1 and corresponds to stage IV pleural mesothelioma.
Finding distant spread is an important part of determining mesothelioma tumor severity because it can significantly affect treatment options.
How CT Scans Help Measure Mesothelioma Tumor Severity
CT scans are an important tool for evaluating pleural mesothelioma.
A CT scan creates detailed images of the chest and can help doctors examine:
- The pleura
- The lungs
- The chest wall
- The diaphragm
- Lymph nodes
- Nearby organs and tissues
Doctors can use CT imaging to look for areas where the cancer has grown or spread.
CT scans may also be performed during treatment to help determine whether the disease is responding, remaining stable, or progressing.
How PET Scans Help
PET scans provide different information from standard CT imaging.
A PET scan uses a radioactive tracer to identify areas of increased metabolic activity. Cancer cells can absorb more of certain tracers than normal cells, which can make areas of cancer easier to identify.
Doctors may combine PET imaging with CT imaging to look for cancer that has spread beyond the primary tumor and to help determine the extent of disease.
PET scans can therefore provide additional information when doctors are evaluating mesothelioma tumor severity.
How MRI Can Provide Additional Information
MRI uses magnetic fields and radio waves to create detailed images of tissues inside the body.
For some patients, MRI can provide additional information about whether mesothelioma has invaded nearby structures.
This can be particularly useful when doctors are evaluating the extent of local disease and determining whether surgery may be possible.
MRI is not necessary for every patient. The imaging tests used depend on the patient’s diagnosis, symptoms, and treatment plan.
How a Biopsy Helps Determine Tumor Severity
Imaging can show doctors where cancer may be located, but imaging alone cannot always confirm that a suspicious area is mesothelioma.
A biopsy involves removing a sample of tissue for examination by a pathologist.
Pathology can confirm the diagnosis and identify the type of mesothelioma.
The cell type can also provide important information about prognosis. For example, epithelioid mesothelioma generally has a more favorable outlook than sarcomatoid mesothelioma.
This is another reason why tumor severity cannot be determined from imaging or tumor size alone.
Clinical Stage vs. Pathological Stage
Doctors may describe mesothelioma using a clinical stage or a pathological stage.
Clinical staging is based on information gathered from physical examinations, imaging tests, biopsies, and other diagnostic procedures.
If a patient undergoes surgery, doctors may obtain additional information by directly examining the extent of the cancer during the procedure.
This can allow them to determine a pathological, or surgical, stage.
The pathological stage may provide a more complete picture because surgery can reveal disease that was not fully visible on imaging.
How Doctors Determine Whether Mesothelioma Can Be Removed
Stage is important, but doctors also consider whether the tumor is resectable.
A resectable tumor is one that doctors believe can potentially be removed with surgery.
An unresectable tumor has grown in a way that prevents surgeons from safely removing all visible disease.
Most stage I and II pleural mesotheliomas and some stage III cases may be considered potentially resectable, although individual circumstances can change that determination. Tumor location, subtype, extent of growth, and the patient’s overall health all matter.
How Mesothelioma Stage Relates to Severity
The stages of pleural mesothelioma range from stage I through stage IV.
Stage I
Stage I generally represents the most localized form of pleural mesothelioma. The cancer remains primarily within the pleura on one side of the chest and has not spread to distant parts of the body.
Stage II
Stage II involves additional local growth or nearby lymph-node involvement, depending on the specific T and N classifications.
Stage III
Stage III represents more extensive local disease and/or regional lymph-node involvement. Some stage III tumors may still be potentially removable with surgery.
Stage IV
Stage IV represents the most advanced stage. It can include extensive local disease or distant metastasis, depending on the specific TNM classification.
Other Factors That Affect Mesothelioma Severity
Stage is important, but it is not the only factor doctors consider.
Other factors can include:
- Age
- Overall health
- Ability to perform normal daily activities
- Mesothelioma cell type
- Blood-cell levels
- Whether surgery is possible
- Response to treatment
- Whether the cancer has returned
The American Cancer Society notes that factors such as younger age, better ability to perform daily activities, female sex, epithelioid histology, and normal blood-cell levels have been associated with longer survival.
This is why two people with the same stage of mesothelioma can still have different treatment plans and outcomes.
Why Measuring Mesothelioma Tumor Severity Matters
Determining the extent of mesothelioma helps doctors decide which treatments may be appropriate.
Patients with more localized and potentially resectable disease may be evaluated for surgery as part of a multimodal treatment approach.
Patients with more advanced or unresectable disease may receive systemic treatments such as chemotherapy or immunotherapy, along with treatments designed to control symptoms and maintain quality of life.
The treatment decision depends on the individual patient rather than stage alone.
Questions to Ask After a Mesothelioma Diagnosis
Understanding the medical terminology can be difficult after a diagnosis.
Patients may want to ask their medical team:
- What stage is my mesothelioma?
- What are my T, N, and M classifications?
- Has the cancer spread to my lymph nodes?
- Has the cancer spread outside the chest?
- Is my tumor considered resectable?
- What did my biopsy show?
- What does my CT or PET scan show?
- What treatment options are available?
- How does my tumor type affect my prognosis?
Getting clear answers can help patients better understand their diagnosis and participate in treatment decisions.
Understanding Mesothelioma Tumor Severity
Mesothelioma tumor severity is determined by much more than tumor size.
For pleural mesothelioma, doctors evaluate the primary tumor, lymph nodes, and distant metastasis through the TNM staging system. CT scans, PET scans, MRI, biopsies, and sometimes surgery provide additional information about how far the disease has progressed.
Doctors also consider the type of mesothelioma, whether the cancer can be removed, the patient’s overall health, and how the disease responds to treatment.
Because every diagnosis is different, patients should discuss their individual stage and treatment options with a medical team experienced in treating mesothelioma.
For more than 35 years, we have represented Pennsylvania workers and families affected by asbestos exposure and mesothelioma. If you or a loved one has been diagnosed with mesothelioma and has questions about asbestos exposure or available resources, call (800) 505-6000 for a free consultation or fill out our online contact form to learn more.
Frequently Asked Questions
How do doctors measure mesothelioma tumor severity?
Doctors measure mesothelioma tumor severity by evaluating how far the cancer has grown, whether nearby lymph nodes are affected, and whether it has spread to distant parts of the body. For pleural mesothelioma, these findings are evaluated using the TNM staging system.
Does tumor size determine how severe mesothelioma is?
No. Tumor size is only one part of determining mesothelioma tumor severity. Doctors also consider the location of the tumor, whether it has invaded nearby structures, lymph-node involvement, distant spread, tumor cell type, and whether the cancer can potentially be removed with surgery.
What does TNM mean in mesothelioma staging?
TNM stands for Tumor, Nodes, and Metastasis. The T category describes how far the primary tumor has grown, the N category describes whether nearby lymph nodes contain cancer, and the M category describes whether the cancer has spread to distant parts of the body.
What tests help doctors determine mesothelioma severity?
Doctors may use CT scans, PET scans, MRI, biopsies, physical examinations, and other diagnostic tests to determine how extensive mesothelioma is. These tests can provide information about the tumor, nearby structures, lymph nodes, and possible distant spread.
How does lymph-node involvement affect mesothelioma severity?
Lymph-node involvement can indicate that mesothelioma has spread beyond the original tumor area. The location and extent of lymph-node involvement can affect the overall stage of pleural mesothelioma and may influence treatment decisions.
Can mesothelioma tumor severity affect whether surgery is possible?
Yes. Doctors consider how extensively the tumor has grown and whether it has invaded important nearby structures when determining whether mesothelioma may be surgically removable. Tumor location, stage, cell type, and the patient’s overall health can all influence whether surgery is appropriate.