Mesothelioma stage plays a large role in prescribed treatment and overall prognosis. It’s important for patients to understand the effectiveness of Positron Emission Tomography (PET) versus Computed Tomography (CT)—2 types of imaging test doctors rely on—to ensure patients receive the most accurate staging and best possible treatment.

What is Mesothelioma Staging?

Mesothelioma staging is the process doctors use to determine the amount of cancer in the body and where it’s located exactly.

Doctors conduct tests  to gain information on 4 important factors:

  1. Where the original tumor is located
  2. The size of the tumor(s)
  3. How far tumors have grown into nearby organs or tissues
  4. If the cancer has spread to lymph nodes

Doctors stage mesothelioma on a scale from 1 to 4:

  • Stage 1 means there is a small tumor that has not grown deeply into nearby tissues or structures.
  • Stage 2 and stage 3 indicate that the cancer has grown more deeply into neighboring organs and possibly lymph nodes.
  • Stage 4 cancers mean that they have spread to other organs and parts of the body.

As a patient’s cancer stage determines which treatment options will be available to them, it’s important to receive an accurate stage diagnosis.

There are 4 different types of staging:

  • Clinical Staging
  • Pathologic Staging
  • Post-Therapy Staging
  • Restaging

Each of these is performed throughout a patient’s diagnosis, treatment and possible relapse. Clinical Staging is used to understand the extent of cancer within the body after the initial diagnosis. Pathologic and post-therapy staging assesses the amount of cancer that remains after treatment. Restaging determines how much cancer has returned after treatment.

For the purpose of this blog post, we will be comparing the effectiveness of 2 imaging tests, PET and CT, used in the initial Clinical Staging.

Comparing PET vs. CT for Mesothelioma Staging

A recent study conducted in March of 2018 compared the M and N staging abilities of both PET and CT tests within pleural mesothelioma patients.

M and N are parts of the TNM Staging System, which is based on the extent of the tumor (T), the spread of the cancer to the lymph nodes (N) and the presence of metastasis or spread to distant areas of the body (M).

The main differences between PET and CT scans are:

  • PET imaging tests reveal changes happening at the cellular level within an organ or tissue.
  • CT scans are good at detecting changes in the physical structure of organs or tissues.

In the study, cancer stages were diagnosed through PET or CT imaging. Surgery acted as a reference point for accurate N or nodal staging 3 months after the initial test for determining metastases (M).

Results showed that PET was able to correctly identify more patients with nodal or distant metastases in comparison to CT imaging. These results mean that PET imaging may be able to more appropriately select mesothelioma patients for surgery or multimodality therapy—an effective combination of surgery, chemotherapy and radiation.

Why Accurate Staging Is Important to Mesothelioma Patients

Knowing your mesothelioma stage is very important. Disease stage helps doctors develop the best multimodal treatment plan, which may include different types of surgery, chemotherapy and radiation.

Correctly identifying mesothelioma stage also helps prepare patients for the chance of recovery and remission, as some stages have higher chances of recovery and return. Accurately identifying a patient’s cancer stage ensures doctors know how effective the prescribed treatment plan will be.

This is important because if a doctor is unable to monitor the effectiveness of a treatment, they will be unable to prescribe a more effective and potentially life-saving treatment plan.

Lastly, if a patient’s mesothelioma is correctly staged, researchers can compare their case back to larger populations with the same diagnosis. Having such accurate information helps specialists know the best treatment methods for similar patients moving forward.

Accurate staging also gives the entire mesothelioma community a better understanding of life expectancies based on more specific patient factors.  

View Author and Sources

  1. British Journal of Radiology, “18F-FDG PET/CT in the management of patients with malignant pleural mesothelioma being considered for multimodality therapy: experience of a tertiary referral center.” Retrieved from: Accessed on March 25, 2018.

Last modified: September 1, 2018