How the Mesothelioma Staging System Could Be Improved
A new study explains how the staging system for malignant pleural mesothelioma could be improved.
By taking tumor volume and weight into consideration, doctors may be
able to diagnose their mesothelioma patients more accurately. More
accurate scoring would help doctors create more accurate treatment plans
for patients.
Using Tumor Volume to Stage Mesothelioma
The most commonly used scoring system takes into account if the tumor
has spread to other parts of the body and the size of the tumor. This
new study, written by Dr. Wickii Vigneswaran, argues that the weight and
volume of tumors may be important factors to consider in staging mesothelioma.
Dr. Wickii Vigneswaran is the division director of Thoracic Surgery
at Loyola University Medical Center and a professor at Loyola University
Chicago Stritch School of Medicine. He is highly experienced in
treating mesothelioma patients and has performed nearly 200 mesothelioma
surgeries.
The title of the study is, “Specimen weight and volume: important
predictors of survival in malignant pleural mesothelioma” and it was
sponsored by the Mesothelioma Heroes Foundation of Chicago. The
researchers wanted to test if tumor volume could be a good predictor of
survival in pleural mesothelioma patients.
Over 6 years, researchers examined 116 patients who were receiving extended pleurectomy and decortication
(EPD) surgery for pleural mesothelioma. Instead of using CT scans to
estimate the volume of the patients’ tumors, the researchers measured
the actual tumors after they were surgically removed.
The study showed that tumors with a higher volume
were associated with shorter survival times. This information could
help develop a new, more detailed staging system.
To measure tumor volume, the researchers used the fluid displacement
method. This method involves putting a solid object into a measured
liquid and seeing how much the volume rises.
Current Staging Systems for Mesothelioma
There are currently three staging systems used for mesothelioma. All
of these systems classify mesothelioma into 4 stages and none of them
take volume or weight into account.
- The Butchart System – The Butchart System focuses on the location of the main tumor instead of the size or the number and spread of cancer cells. Dr. Eric Butchart developed this system in 1976 making it the first mesothelioma staging system.
- The Brigham System – This system focuses on the location, size, and spread of the cancer. This system was developed by Dr. David Sugarbaker while he was at Brigham and Women’s Hospital.
- TNM Staging System – The TNM system focuses on evaluating the tumor (T), the spread to the lymph nodes (N), and metastasis (M). This system was developed by the American Joint Committee on Cancer (AJCC).
TNM Staging
The tumor/node/metastasis or TNM system is now the most commonly used
system to stage cancer, including mesothelioma. The diagnosis of stage 1
through 4 is decided based on 3 categories represented by T, N, and M.
The categories are rated by the extent of cancer with X or a number 0
through 4. X means that category couldn’t be evaluated properly. Then
0-4 represent the severity of the cancer, 0 being the least cancer and 4
being the most.
- Tumor: This category evaluates the main tumor and how much it has grown and spread. TX means that the tumor can’t be assessed. Then the range of tumor growth can be measured from T0, meaning that there is no evidence of a main tumor, to T4, meaning the tumor has grown too far to be surgically removed.
- Node: This category evaluates whether the cancer has spread to the nearby lymph nodes and how much. NX means the lymph nodes cannot be assessed. N0 means there has been no spread to nearby lymph nodes. N3 is the highest rating which means that the cancer has spread to lymph nodes on the opposite side of the body from the main tumor.
- Metastasis: This category evaluates whether the cancer has spread to other organs. Metastasis is only evaluated as 0 or 1. M0 means that there has been no spread to distant organs or areas. M1 means the cancer has spread to distant organs or areas.
While the TNM staging system has proven effective
enough to become the most popular staging system for cancer, it may not
be precise enough when it comes to mesothelioma. Mesothelioma is unique
in that it spreads itself out unevenly around an organ and is similar
in density to the healthy tissues around it.