Pleural Mesothelioma Staging: These Overlooked Lymph Nodes Might Help

An often-ignored set of lymph nodes behind the ribs could help make pleural mesothelioma staging more accurate and valuable. 

Staging is the process of determining how advanced a patient’s cancer is. It involves looking at various different factors and assigning a rating between 0 and 4. A higher stage indicates more extensive cancer.

A new report suggests that the posterior intercostal lymph nodes behind the ribs play a more important role in pleural mesothelioma staging than previously thought. Mesothelioma patients with cancer in these nodes lived half as long as other mesothelioma patients. 

Researchers in Maryland and Pennsylvania say removing and examining these nodes may lead to more accurate staging, more informed treatment decisions, and better outcomes.  

How Lymph Nodes are Involved in Cancer Staging

Lymph nodes are small bean-shaped structures found throughout the body. They are part of the immune system. 

The job of the lymph nodes is to filter substances that travel through the lymphatic fluid. In people with cancer, this can include cancer cells. Removing and examining lymph nodes for signs of mesothelioma can help doctors determine how far the cancer has spread.

Different parts of the body drain into different sets of lymph nodes. When a surgeon performs cancer surgery, he typically also removes the lymph nodes that are most likely to be affected. These lymph nodes are then used in pleural mesothelioma staging.  

The Role of Intercostal Lymph Nodes in Pleural Mesothelioma Staging

Pleural mesothelioma is a fast-growing cancer associated with asbestos exposure. It starts on the membrane around the lungs. 

Lymphatic fluid in this space drains into a set of lymph nodes in the center of the chest directly behind the heads of the ribs. These are the posterior intercostal lymph nodes. 

These lymph nodes are not usually part of pleural mesothelioma staging. But cancer research at the University of Pennsylvania and the University of Maryland suggests that they probably should be. 

Nodes Could Help Direct Mesothelioma Treatment

Researchers removed and tested the posterior intercostal lymph nodes in 56 consecutive mesothelioma surgery patients. They found that when these particular lymph nodes were involved, the patient’s prognosis was “significantly poorer”.

This was true even in patients with the same cancer stage. Overall, study subjects with Stage 2 mesothelioma lived for more than 26 months. But the Stage 2 patients with positive posterior intercostal lymph nodes died at a median of just 14.4 months. 

Nearly half of the mesothelioma patients tested had cancer cells in their posterior intercostal lymph nodes. In 11 percent of patients, these were the only lymph nodes involved. 

“This first reported series of posterior intercostal lymph nodes revealed they independently more than doubled the risk of progression and death,” concludes lead researcher Joseph Friedberg, MD.

Dr. Friedberg and his colleagues say these nodes should be studied further for their potential in pleural mesothelioma staging. They hope to find ways to test them without doing surgery which could make them more useful for mesothelioma treatment planning. 

Source:

Friedberg, JS, et al, “This first reported series of posterior intercostal lymph nodes revealed they independently more than doubled the risk of progression and death”, October 18, 2019, Annals of Thoracic Surgery, Epub ahead of print, https://www.annalsthoracicsurgery.org/article/S0003-4975(19)31588-7/pdf