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

Our plain-English summary of Posterior Intercostal Lymph Nodes Double Recurrence and Death Risk in Malignant Pleural Mesothelioma, by J.S. Friedberg, C.B. Simone, M.J. Culligan, et al (The Annals of Thoracic Surgery, 2020).

The study

• Authors: J.S. Friedberg, C.B. Simone, M.J. Culligan, M.E. Putt, A.R. Barsky, S. Katz, K.A. Cengel
• Journal: The Annals of Thoracic Surgery
• Published: 2020;110(1):241-250
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: 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.

Methods: 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.

Results: 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).

Conclusions: 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.

Copyright © 2020 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

In plain English

This study examined posterior intercostal lymph nodes, located in the chest wall beside the spine, in malignant pleural mesothelioma. It analyzed the last 56 consecutive patients from two prospective clinical trials. All had epithelioid mesothelioma and were treated with extended pleurectomy/decortication and photodynamic therapy during surgery. Fifty-two received chemotherapy; four with cancer in these nodes could not, because their disease returned quickly and their condition declined. Surgeons removed these nodes in every patient and found cancer in them in 27 of the 56. In 6 patients (11%) they were the only lymph nodes with cancer. After adjusting for nodal stage, sex, age and overall stage, patients with cancer in these nodes had 2.5 times the risk of disease progression (95% confidence interval 1.6 to 4.0) and 2.2 times the risk of death (1.4 to 3.4) of patients with negative nodes. The authors concluded these nodes should be routinely removed in surgery meant to cure; larger studies are needed. They noted the finding could be artifactual, coming from one institution with a modest number of patients. Asbestos exposure was not examined.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Subset analysis of patients consecutively enrolled in two prospective clinical trials (single institution)
• Who was studied: 56 consecutive patients with epithelioid malignant pleural mesothelioma. All were treated with extended pleurectomy/decortication and intraoperative photodynamic therapy, and 52 of 56 also received chemotherapy. 78.6% were male and the median age was 64.7 years. The last surgery was in April 2014, with follow-up through December 2018.
• Exposure: No asbestos exposure was studied. The factor studied was whether mesothelioma had spread to posterior intercostal lymph nodes, which were removed during surgery.
• Main results:
  • 27 of the 56 patients had metastatic mesothelioma in posterior intercostal lymph nodes; 29 were negative.
  • In 6 patients (11%), posterior intercostal lymph nodes were the only lymph nodes with metastases.
  • Four patients did not receive chemotherapy (52 of 56 did, per Table 1). These four had positive posterior intercostal nodes and experienced rapid recurrence and decline of performance status after surgery, which precluded postoperative chemotherapy.
  • Among patients already classed N2 (AJCC 7th edition), those with posterior intercostal node metastases had shorter median progression-free survival (7.3 vs 14.9 months) and overall survival (14.4 vs 26.1 months, per the text).
  • After stratifying for nodal status, median progression-free survival was 7.3 months in patients with positive posterior intercostal nodes vs 15.8 months in those with negative nodes (p = 0.004).
  • In a simple model adjusting for N stage only, patients with positive posterior intercostal nodes had a 1.9-fold relative risk of progression (95% CI 1.1 to 3.3, p = 0.019) and a 1.7-fold relative risk of death (95% CI 1.0 to 2.8, p = 0.040), compared with patients with negative nodes.
  • In the multivariable model (also including age, sex and AJCC stage), patients with positive posterior intercostal nodes had a 2.5-fold relative risk of progression (95% CI 1.6 to 4.0, p less than 0.001) and a 2.2-fold relative risk of death (95% CI 1.4 to 3.4, p = 0.001), compared with patients with negative nodes.
  • Posterior intercostal node metastases were not detected before surgery in these patients, despite full radiologic staging including PET/CT.
• The authors' conclusion: The authors concluded that posterior intercostal lymph nodes should be routinely harvested during surgery with therapeutic intent for malignant pleural mesothelioma, because they may be the only nodes containing cancer. They said larger studies are needed, and that from this series these nodes appear to carry a prognosis at least equal to AJCC 8th edition N1 nodes.
• Limitations the authors state:
  • The finding could be artifactual, because the study came from a single institution and had a modest number of patients.
  • The series contained no patients with AJCC 8th edition N2 metastases to serve as a comparison group.
  • A larger, preferably multi-center, series is needed.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Staging, Pleurectomy/Decortication (P/D), Endothoracic Fascia, Clinical Trial, Overall Survival, Prognosis.

Related studies

• Lymph node involvement and metastatic lymph node ratio influence the survival of malignant pleural mesothelioma: a French multicenter retrospective study — I. Hysi, F. Le Pimpec-Barthes, et al. (2014)
• The prevalence of enlarged mediastinal lymph nodes in asbestos-exposed individuals: a CT study — C. Sampson, D.M. Hansell (1992)
• Lymph node metastases in diffuse malignant peritoneal mesothelioma — D. Baratti, S. Kusamura, et al. (2010)
• Asbestos content of lung tissue, lymph nodes, and pleural plaques from former shipyard workers — R.F. Dodson, M.G. Williams, et al. (1990)
• Intrapulmonary lymph nodes. Clinical, radiologic, and pathologic features — R.L. Kradin, P.W. Spirn, et al. (1985)
• Hyperplastic mesothelial cells in lymph nodes: report of six cases of a benign process that can stimulate metastatic involvement by mesothelioma or carcinoma — P. Argani, J. Rosai (1998)

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