Lymph Nodes in Rib Cage Could Help Staging and Treatment of Mesothelioma

Update: This article was originally published in 2014 and was updated January 6, 2023 with more information about mesothelioma staging and the likelihood of a misdiagnosis.

Research coming out of the Perelman School of Medicine at the University of Pennsylvania could help improve staging and treatment of pleural mesothelioma.

A presentation by Joseph S. Friedberg, MD, at the 15^th World Conference on Lung Cancer in 2014 showed the benefits of studying a previously overlooked set of lymph nodes in the rib cage.

Examining the lymph nodes in cancer patients is essential for staging. When cancer cells start to spread, the lymph system is often used as a pathway. Therefore, the presence of cancer cells at the lymph nodes indicates the cancer is more advanced.

The posterior intercostal lymph nodes in particular lie between the ribs and near the spine. Although lymph nodes are commonly used for staging all kinds of cancer, the posterior intercostal set is rarely sampled for mesothelioma.

 

Staging Mesothelioma

Staging is used to determine a prognosis for cancer, which often helps establish the most effective way to treat it. In general, the more that can be known about a patient’s condition, the more effective treatment will be.

Presently, most mesothelioma doctors rely on a model of staging by the American Joint Committee on Cancer called TNM. This system considers three key pieces of information:

• T looks at the extent of the spread of the main or primary tumor. TX means the tumors cannot be measured. T0 means the tumors can’t be found. T1, T2, T3 and T4 range in size and spread of tumors.
• N describes how much the cancer has spread to nearby or regional lymph nodes.  NX means lymph node involvement can’t be evaluated. N0 means there is no lymph node involvement. N1, N2 and N3 range in how many are affected and how much they’ve swollen.
• M indicates whether the cancer has spread, or metastasized, to other organs. M0 means no metastasis has occurred (the disease remains local). M1 means the mesothelioma has spread to distant organs or tissues.

 

Lymph Nodes in the Rib Cage Offer Insight into Mesothelioma Staging

Dr. Friedberg at the time of the study was Chief of the Section of Thoracic Surgery at Penn Presbyterian Medical Center and Co-Director of the Penn Mesothelioma and Pleural Disease Program.

He moved to the University of Maryland Cancer Center and now works at the Temple University Health System as the Co-Director of the Temple Health Mesothelioma and Pleural Disease Program.

He and his colleagues at Penn Medicine launched a retrospective study of 48 patients undergoing radical pleurectomy for malignant pleural mesothelioma.

“I am unaware of any other group that is sampling these nodes. They are not currently part of the staging system for mesothelioma, or any other cancer for that matter,” said Dr. Friedberg in a press release. “What we have shown here is that even though these lymph nodes are not described in relation to this cancer, they are highly significant.”

The study found that more than half of the patients had cancer metastatic to these lymph nodes and that, in some of these patients, those were the only lymph nodes containing metastatic cancer. This means the lymph nodes in the rib cage were the primary set of nodes affected by mesothelioma cancer

The Penn Medicine study also showed that those who did not have cancer present in these lymph nodes survived up to 2.5 years longer than those who did. These lymph nodes hold predictive properties for mesothelioma survival and should be considered when making a diagnosis and giving patients a prognosis of life expectancy.

 

The Importance of Effective Staging

The need for more effective staging is an important issue in diagnosing mesothelioma. Because the disease is already hard to diagnose due to its rarity, misdiagnosis is common. In addition, the existence of several staging systems introduces the problem of a patient getting a different diagnosis from different doctors.

The study conducted by Dr. Friedberg shows there is potential to prevent diagnosing patients at the wrong stage of the disease. The reason this is particularly important is because if a patient is diagnosed at a later stage they typically have fewer treatment options.

How Often Does Incorrect Staging Happen for Mesothelioma?

A study published in the Journal of Thoracic Oncology analyzed 1,056 mesothelioma patients for how often a misdiagnosis occurred for each stage:

• 80.8% of stage 1 mesothelioma were incorrectly diagnosed and later “upstaged” to a more-advanced stage.
• 69.5% of stage 2 mesothelioma were misdiagnosed.
• 35.4% of stage 3 mesothelioma were inaccurate.
• 12.8% of stage 4 mesothelioma were incorrectly diagnosed and later “downstaged.”
• Approximately 47% of patients were upstaged.
• Only 4.6% were downstaged.

Upstaging a cancer diagnosis means giving it a later stage (such as upstaging from stage 2 to stage 3). Downstaging a cancer diagnosis is the opposite, reducing the stage and giving patients a better prognosis.

Patients who are in the early stages for mesothelioma are normally eligible for life-saving surgeries. However, if they are diagnosed at a later stage, doctors may not recommend surgery. This conversely applies to patients to whom surgery would do more damage than good.

 

Other Staging Systems for Mesothelioma

In addition to the TNM Staging System, there are two other staging systems commonly used by mesothelioma doctors — the Butchart System and the Brigham System.

The Butchart System, developed in 1979, is the oldest staging system for mesothelioma. This system relies predominantly on the size and location of mesothelioma tumor to determine stage. For example, if the tumor is present in both sides of the chest, and hasn’t penetrated the pleura, the patient is generally said to be in stage 2.

The Brigham System was developed by Dr. David Sugarbaker, who passed away in 2018, and gets its name from Brigham and Women’s Hospital. This system is similar to the TNM system but is used specifically to determine if surgery is an option. Therefore, staging guidelines under this system may be more liberal.