Mesothelioma Staging: What You Need to Know

One of the most basic elements of how we talk about mesothelioma involves staging, which is a crucial step in evaluating a patient’s condition and mapping a path forward for treatment. However, the concept of staging may be unfamiliar to mesothelioma patients and their families, especially if they have not gone through the cancer diagnosis process before. In this article, we’ll explain how mesothelioma staging works, why it’s important, and what mesothelioma patients and their families should know about this essential step in their mesothelioma journey.

What is mesothelioma cancer staging?

Mesothelioma staging refers to a descriptor for the extent and severity of a patient’s cancer, as evaluated at the time of their diagnosis. This includes things like how large tumors may be and where they are located, as well as whether the mesothelioma has spread to nearby tissues, lymph nodes, organs, and other parts of your body.

Importantly, mesothelioma staging describes the state of a patient’s mesothelioma at the time of diagnosis, and does not change as the disease progresses and/or improves. A patient’s mesothelioma stage remains the same even if a tumor grows or shrinks in size.

Why is mesothelioma staging important?

Mesothelioma staging gives doctors more information about a patient’s condition and helps them formulate the best and most effective treatment plan. It helps them arrive at a prognosis, or an estimate of how advanced a patient’s mesothelioma is and their chances of survival. Cancer staging can also help mesothelioma care teams identify any clinical trials patients may be eligible for, potentially helping to improve prognosis and quality of life.

Are there different systems that are used for staging?

Yes, different systems are generally used to stage different types of mesothelioma.

For pleural mesothelioma, the standard method of staging is the TNM (Tumor, Node, Metastasis) staging system. This is the most common and widely used cancer staging system. The TNM system measures:

• T: The Main Tumor: The size and extent of the largest or farthest advanced tumor (sometimes called the “primary tumor”).
• N: Lymph Nodes: Whether the mesothelioma has spread to nearby lymph nodes, and if so, how many.
• M: Metastasis: Whether the mesothelioma has metastasized, or spread from the pleural area to other parts of your body.

Depending on the TNM staging criteria, patients are given a diagnosis that fits into one of four broad “stages” (Stages 1-4, or I-IV).

TNM staging also involves the use of numbers after each letter, sometimes along with additional letters, numbers, or symbols, each of which give additional information about your condition. Ask your mesothelioma care team to explain what the letters and numbers mean for your staged diagnosis.

For peritoneal mesothelioma, oncologists generally do not use the same TNM system used for pleural mesothelioma. Instead, they may use:

• A modified version of the TNM system developed by medical professor Tristan D. Yan and the Peritoneal Surface Oncology Group International.
• Peritoneal Cancer Index (PCI), a tool that assesses peritoneal cancers like mesothelioma across 13 abdominal regions, each of which is scored from 0-3 (with 0 indicating no mesothelioma present, and 3 indicating the presence of malignant mesothelioma). These scores are ultimately added for a total score of 1 to 39, which roughly reflects or estimates a peritoneal mesothelioma patient’s staging, as follows:
  • Stage 1: PCI score of 1-10
  • Stage 2: PCI score of 11-20
  • Stage 3: PCI score of 21-30.
  • Stage 4: PCI score of 31-39.

There are no formal staging systems for pericardial and testicular mesothelioma, which are both far rarer than pleural or peritoneal mesothelioma. Generally, oncologists staging these forms of mesothelioma adapt an existing staging system to their needs, or evaluate staging based on MRI and CT scans and/or tumor marker tests.

For treatment purposes, staging may also involve evaluating whether your mesothelioma is considered resectable (if the entire visible primary tumor can be removed by surgery) or unresectable (if the tumor cannot be completely removed by surgery). Generally, mesothelioma is most likely to be resectable in earlier stages, though there are exceptions. The question of resectable vs. unresectable also depends on factors like tumor location, whether the patient is healthy enough for surgery, and mesothelioma subtype (as it is generally believed that only some types of mesothelioma tumors—specifically epithelioid and mixed/biphasic tumors—are resectable).

Mesothelioma oncologists may also use the following terms to describe a patient’s cancer, which roughly correlate to staging:

• In situ, meaning abnormal mesothelioma cells are present but have not spread to nearby tissue.
• Localized, meaning mesothelioma is present but has not spread beyond the mesothelial area where it started.
• Regional, meaning mesothelioma has spread beyond the specific place of origin, to nearby tissues, lymph nodes, or organs.
• Distant, meaning mesothelioma has metastasized and spread to distant parts of the body.

What sort of tests are conducted during mesothelioma staging?

Mesothelioma staging generally involves a variety of tests, often performed during the mesothelioma diagnosis process. These can include imaging scans, like CT scans, MRI scans, X-rays, and PET scans, as well as biopsies. Your mesothelioma care team may also opt to use exploratory procedures like laparoscopy or endoscopy, to look at the inside of your body first-hand.

Are you or a loved one looking for more information about mesothelioma? Call (855) 385-9532 to learn more.