The Annals of Thoracic Surgery 2019 October 18 [Link]
Friedberg JS, Simone CB 2nd, Culligan MJ, Putt ME, Barsky AR, Katz S, Cengel KA
Posterior intercostal lymph nodes, previously undescribed for cancer staging, are part of the lymphatic drainage of the pleural space. The purpose of this study was to assess the impact of posterior intercostal lymph nodes on survival in patients undergoing surgery for malignant pleural mesothelioma.
As part of the thoracic lymphadenectomy, posterior intercostal lymph nodes were accessed by incising the endothoracic fascia at the level of the rib heads. These nodes were systematically harvested in 56 consecutive patients undergoing extended pleurectomy decortication in a clinical trial. The impact of these nodes on both progression free and overall survival was then analyzed by multiple statistical methods.
Median PFS/OS were 11.6/25.5 months, respectively. In 6/56 (11%) posterior intercostal lymph nodes were the only positive nodes and, overall, 48.2% had posterior intercostal lymph node metastases. Patients with N2 disease had significantly poorer prognosis if the posterior intercostal lymph nodes were involved: PFS (7.3 vs 14.9 months, p=0.002) and OS (14.4 vs 26.1 months, p = 0.028). In the multivariable models, after adjustment for nodal stage and other prognostic factors, intercostal nodes remained associated with a 2.5 fold elevated risk of progression (p<0.001) and a 2.3 fold elevated risk of death (p<0.001).
This first reported series of posterior intercostal lymph nodes revealed they independently more than doubled the risk of progression and death and in 11% of the patients were the only metastatic nodes. These nodes warrant further investigation, including non-operative techniques to identify and factor them into treatment decision making.