01. Defining the TNM Staging System
What Is the TNM Staging System?
The TNM staging system is the most common staging system forpleural mesothelioma。It is also used to stage several other cancers, includinglung cancerand breast cancer.
The TNM classification system uses three components to determine cancer stage:
- Tumor extent (T):The location and size of the primary tumor site
- Lymph node involvement (N):Whether the cancer has spread to nearby lymph nodes
- Metastasis (M):Whether the cancer is localized or has spread to distant areas of the body
A doctor scores each component and assigns a value. A doctor will use the scores to determine themesothelioma stagebetween 1 and 4.
The system is maintained by the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control (UICC).
Other Mesothelioma Staging Systems
In 1994, the International Mesothelioma Interest Group (IMIG) published the first widely accepted TNM classification for malignant pleural mesothelioma. Although the TNM system is most commonly used, there are other systems used to stage mesothelioma.
Less common staging systems for万博专业版are:
- The Butchart staging system
- The Brigham staging system
In some cases, doctors have used a modified TNM system to stageperitoneal mesothelioma。The Peritoneal Cancer Index (PCI) is also used for staging peritoneal mesothelioma.
02. Understanding TNM Classification
How Doctors Use the TNM System to Classify Cancer
To determine mesothelioma stage using the TNM system, doctors will score each category of the system using letters and numbers. Tumor extent, lymph node involvement and metastasis together determine the overall stage.
Clinicians may score each category using physical exams,imaging testsandbiopsy results。This is called clinical staging. Mesothelioma patients are typically given a clinical stage.
In some cases, doctors may update staging information after surgical removal of tumors. This is called surgical staging.
Surgery allows physicians to visualize and assess tumor size and spread. Therefore the surgical stage may differ slightly from the clinical stage.
Classifying Tumor Extent
Tumors are given a designation of T1, T2, T3 or T4. The designation depends on the size of the primary tumor site and its spread to nearby tissues.
Although tumor size and extent may provide an indication of prognosis, it alone cannot classify the cancer stage. It must be considered in combination with lymph node involvement and metastasis.
Classifying Lymph Node Involvement
Lymph node involvement is the spread of cancerous cells from the primary tumor site to nearby lymph nodes.
In early stages, cancer has either not spread to the lymph nodes at all or has only spread to nearby lymph nodes. In later stages, distant lymph nodes are affected.
Lymph node involvement is graded as NX, N0, N1 or N2.
Lymph node involvement is an important factor for staging mesothelioma. If cancer cells spread to the lymph nodes, it increases the likelihood of distant metastasis in the body. As cancer spreads, patients may face more limited treatment options and a less favorable prognosis.
Classifying Metastasis
Cancer metastasis is the spread of cancer from its origin. Metastasis can lead to tumors growing beyond the primary tumor site in distant areas of the body.
Mesothelioma metastasisplays an important role in TNM classification. It is scored as either M0 or M1.
In pleural mesothelioma cases, metastasis may indicate cancer has spread to the opposite side of the chest and abdominal lining.
Resources for Mesothelioma Patients
03. Determining Mesothelioma Stage
Determining Mesothelioma Stage Using the TNM System
After each category of the TNM system is scored, the doctor combines the information in a process called stage grouping. During stage grouping, physicians classify the mesothelioma cancer as:
- Stage 1A or 1B
- Stage 2
- Stage 3A or 3B
- Stage 4
In the earlier stages, mesothelioma is considered less advanced and patients may be eligible for more aggressive treatment options, such as invasivesurgery。后期可能意味着间皮瘤细胞万博专业版spread to distant parts of the body, which may limit a patient’s treatment options.
| Stage | T | N | M |
| 1A | T1 | N0 | M0 |
| 1B | T2, T3 | N0 | M0 |
| 2 | T1, T2 | N1 | M0 |
| 3A | T3 | N1 | M0 |
| 3B | T1-3 | N2 | M0 |
| 4 | T4 | N0-2 | M0 |
| Any T | Any N | M1 |
Determining stage allowsmesothelioma doctorsto provide patients with an accurate prognosis. Typically, patientsdiagnosed with mesotheliomainstage 1andstage 2have better survival rates than those diagnosed instage 3orstage 4 cancer。
Other Factors That Impact Prognosis
The TNM system helps doctors assessmesothelioma prognosis。However, additional patient characteristics may impact prognosis andmesothelioma life expectancy。
Factors that may impactmesothelioma survival rateinclude:
- Age
- Sex
- Cell type (上皮样的,biphasicorsarcomatoid)
- Medical history
Physicians will assess prognosis based on the TNM stage and unique patient characteristics. These factors also help clinicians determine the best way to move forward with treatment.
04. TNM System Updates
TNM Staging System Updates
The TNM staging system is frequently updated as new information emerges.Mesothelioma researchandclinical trialshelp experts continuously improve the staging system.
我的最新版本TNM系统s theeighth edition of the TNM classification for malignant pleural mesothelioma。The most up-to-date version is reflected in the latestAJCC Cancer Staging Manual。
系统的更新是由国际肺癌（IASLC）分期和预后因素委员会（SPFC）研究的协会作出的。UICC和AJCC批准了更新。
The eighth edition was implemented in January 2017 but was not widely used in the United States until 2018.
Mesothelioma research is consistently improving diagnostic tools and treatments. Updates to the TNM system help doctors provide patients with the most accurate prognosis and treatment plan.
