For the first time, researchers from the Perelman School of Medicine at the University of Pennsylvania have shown the predictive power of a group of overlooked lymph nodes--known as the posterior intercostal lymph nodes--that could serve as a better tool to stage and ultimately treat patients with malignant pleural mesothelioma.

The findings were presented October 28 at the 15th World Conference on Lung Cancer.

Physicians look to lymph nodes to stage essentially all cancers, including mesothelioma. The presence or absence of metastatic cancer cells in lymph nodes affects prognosis and also typically dictates the optimal treatment strategy.   But posterior intercostal lymph nodes, which are located between the ribs near the spine, have not been previously used to stage or guide treatment of malignant pleural mesothelioma or any other cancer.

In a retrospective study of 48 Penn Medicine patients undergoing radical pleurectomy for malignant pleural mesothelioma, Joseph S. Friedberg, MD, Chief of the Section of Thoracic Surgery at Penn Presbyterian Medical Center and Co-Director of the Penn Mesothelioma and Pleural Disease Program, and colleagues found that over half 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. 

Patients who did not have cancer in the posterior intercostal lymph nodes had significantly longer overall survival rates, nearly two and half years longer, compared to those who did have cancer in the lymph nodes.

“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. “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 conclusion of the study was that surgeons should routinely biopsy these lymph nodes as part of any surgery-based treatment for mesothelioma and that these lymph nodes should be included in any revision of the mesothelioma staging system.

“Ultimately, it means that the presence or absence of cancer in these lymph nodes could help guide the treatment of pleural mesothelioma,” said Dr. Friedberg.

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