Posterior Intercostal Lymph Nodes Double Recurrence and Death Risk in Malignant Pleural Mesothelioma

Abstract

Posterior intercostal lymph nodes, previously undescribed for cancer staging, are part of the lymphatic drainage of the pleural space. This study assessed the impact of posterior intercostal lymph nodes on survival in patients undergoing extended pleurectomy/decortication 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 progression-free (PFS) and overall survival (OS) was analyzed by multiple statistical methods. Median PFS and OS were 11.6 and 25.5 months, respectively. In 6 of 56 patients (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= .002) and OS (14.4 vs 26.1 months, P= .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 < .001) and a 2.3-fold elevated risk of death (P < .001). Metastases to posterior intercostal lymph nodes independently more than doubled the risk of progression and death and were the only site of nodal metastases in 11% of patients. These nodes warrant further investigation, including nonoperative techniques to identify and factor them into treatment decision making.