Clinicopathological features of radiological early malignant pleural mesothelioma with no apparent tumor or pleural thickening

Our plain-English summary of Clinicopathological features of radiological early malignant pleural mesothelioma with no apparent tumor or pleural thickening, by A. Nakamura, M. Hashimoto, H. Kodama, et al (International Journal of Clinical Oncology, 2021).

The study

• Authors: A. Nakamura, M. Hashimoto, H. Kodama, M. Yuki, N. Kondo, K. Yamakado, T. Tsujimura, T. Kijima, S. Hasegawa
• Journal: International Journal of Clinical Oncology
• Published: 2021;26(1):95-103
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: We occasionally encounter malignant pleural mesothelioma (MPM) of no apparent tumor or pleural thickening that is radiological early MPM. This study aimed to examine the clinicopathological outcomes of radiological early MPM.

Methods: Patients with MPM treated with neoadjuvant chemotherapy and planned surgery at the time of diagnosis between July 2004 and December 2019 were retrospectively examined. Pretreatment maximal pleural thickness of all patients was measured on chest computed tomography. We extracted and investigated the patients who exhibited a lack of pleural thickening or visible tumor, which was defined as radiological early MPM. Survival was analyzed by the Kaplan-Meier method.

Results: Of 296treated patients, 16 (5.4%) exhibited radiological early MPM. Fourteen (87.5%) of these patients underwent pleurectomy/decortication and 2 (12.5%) underwent extrapleural pneumonectomy. Pathological stage T1 disease was diagnosed in 14 (87.5%) patients; 2 (12.5%) exhibited pulmonary parenchymal invasion (pathological stage T2). Lymphatic invasion was detected in only 1 patient. Lymph node metastases and vascular invasion were not detected. Median follow-up was 42 months. Median progression-free survival and median overall survival were 40.7 and 56.1 months, respectively. The 3-year progression-free survival and overall survival rates were 84.8% and 83.6%, respectively.

Conclusions: Radiological early MPM occurs in approximately 1 of every 20 patients treated with neoadjuvant chemotherapy and surgery planned at the time of diagnosis in an experienced center. Radiological early MPM was associated with early pathological stage and long-term survival.

In plain English

This was a retrospective study from one hospital in Japan. It looked at patients with malignant pleural mesothelioma recorded between July 2004 and December 2019 who received chemotherapy before planned surgery. The authors measured pleural thickness on CT scans taken before treatment and singled out patients with no visible pleural thickening or tumor, which they called radiological early mesothelioma. Of 296 patients, 16 (5.4%) met this definition. Of these 16, 14 had pleurectomy/decortication and 2 had extrapleural pneumonectomy, and none died within 90 days. All 16 tumors were epithelioid. Fourteen were pathological stage T1 and 2 were T2. No lymph node spread or vascular invasion was found, and lymphatic invasion was seen in 1 patient. Over a median follow-up of 42 months, 7 of the 16 had a recurrence. In this group, 3-year overall survival was 83.6% (median 56.1 months) and 3-year progression-free survival was 84.8% (median 40.7 months). The authors concluded that this form was associated with early pathological stage and good long-term survival. They noted that the single-center design may have introduced bias. The article does not report asbestos exposure.

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: Retrospective review of a prospective single-hospital surgical database; survival analyzed by the Kaplan-Meier method
• Who was studied: 296 patients with malignant pleural mesothelioma at Hyogo College of Medicine, Japan, registered July 2004 to December 2019 for neoadjuvant chemotherapy and planned surgery; 16 of them (median age 67, range 51 to 79; 10 men) had radiological early MPM
• Main results:
  • Radiological early MPM was found in 16 of 296 treated patients (5.4%)
  • Among the 16 radiological early MPM patients, 14 (87.5%) had pleurectomy/decortication and 2 (12.5%) had extrapleural pneumonectomy; 30- and 90-day mortality were both 0%
  • Among the 16, 2 (12.5%) had pulmonary parenchymal invasion (pathological T2); the other 14 were pathological T1
  • Among the 16, no lymph node metastases or vascular invasion were found, and lymphatic invasion was found in 1 patient (6.3%)
  • Over a median follow-up of 42 months (range 8 to 77), 7 of the 16 (43.8%) had a recurrence
  • Among the 16, 2- and 3-year overall survival rates were 92.9% and 83.6% (median overall survival 56.1 months)
  • Among the 16, 2- and 3-year progression-free survival rates were both 84.8% (median progression-free survival 40.7 months)
  • Of the 16, 6 patients died; 1 of them died without evidence of tumor recurrence
• The authors' conclusion: The authors concluded that radiological early MPM occurs in about 1 of every 20 patients treated with neoadjuvant chemotherapy and planned surgery in an experienced center. They concluded it was associated with early pathological stage and good long-term survival, and they called for prospective nationwide studies.
• Limitations the authors state:
  • The single-center design may have introduced bias.
  • Japanese centers operate earlier than centers in the USA and Europe, so the frequency there is probably lower.
  • Radiological early MPM was not compared with other clinical T stages; future studies are 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, Pleural Thickening, Neoadjuvant Chemotherapy, Pleural Thickness, Pleurectomy/Decortication (P/D), Extrapleural Pneumonectomy (EPP), Progression-Free Survival, Median Overall Survival.

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• Radiological characteristics, histological features and clinical outcomes of lung cancer patients with coexistent idiopathic pulmonary fibrosis — K.A. Khan, M.P. Kennedy, et al. (2015)
• Increased body mass index is related to apparent circumscribed pleural thickening on plain chest radiographs — Y.C. Lee, C.K. Runnion, et al. (2001)
• A retrospective study on radiological findings of diffuse pleural thickening with benign asbestos pleural effusion in Japanese cases — T. Kishimoto, K. Kato, et al. (2022)
• Radiological features of diffuse mesothelioma — A. Solomon (1970)
• Malignant pleural mesothelioma: clinicopathology of 16 extrapleural pneumonectomy patients with special reference to early stage features — K. Hiroshima, T. Yusa, et al. (2009)

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