The Role of Dosimetric Parameters in Radiation Pneumonitis: A Functional Approach in Adjuvant Treatment of Malignant Pleural Mesothelioma

Our plain-English summary of The Role of Dosimetric Parameters in Radiation Pneumonitis: A Functional Approach in Adjuvant Treatment of Malignant Pleural Mesothelioma, by L. Dominici, D. Franceschini, M. Loi, et al (Cancers, 2026).

The study

• Authors: L. Dominici, D. Franceschini, M. Loi, R. Spoto, A.M. Marzo, B. Marini, M.B. Ilieva, N. Lambri, F. La Fauci, C. Franzese, M. Scorsetti
• Journal: Cancers
• Published: 2026;18(3)
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant pleural mesothelioma (MPM) is an aggressive neoplasm, the major cause of which is asbestos exposure. Adjuvant radiotherapy after pleurectomy/decortication (P/D) aims at reducing locoregional recurrence but is limited by the risk of radiation pneumonitis (RP). In this study, we attempted to evaluate the predictive value of conventional and functional dosimetric parameters in assessing RP risk.

Methods: This retrospective study analyzed 68 patients with non-metastatic MPM treated with adjuvant radiotherapy after P/D. Dosimetric parameters, including V20, V5, and mean lung dose (MLD), were calculated for both total lung volume and functional lung volume (FLV), with emphysematous regions excluded based on CT imaging thresholds. Statistical analyses assessed correlations between these parameters and acute RP incidence.

Results: Acute RP developed in 42% of patients, and 28% had moderate-to-severe (Grade 2-3) events. V20 and FCL_V20 were significantly associated with the risk of RP (p = 0.017 and p = 0.028, respectively). Predictive accuracy for conventional V20 (AUC = 0.668) and Functional Contralateral Lung V20 (FCL_V20) (AUC = 0.655) showed moderate efficacy, without further significant improvement in using functional parameters. A V20 threshold > 1.8% predicted severe RP with high specificity (89.8%).

Conclusions: While functional lung delineation provides an alternative in dosimetry, conventional V20 is a robust predictor of RP. Optimization of dosimetric constraints, in an effort to reduce pulmonary toxicity in MPM patients, should be further combined with advanced radiotherapy techniques and biomarkers.

In plain English

This retrospective, single-center Italian study looked at 68 patients with non-metastatic malignant pleural mesothelioma. All had lung-sparing surgery (pleurectomy/decortication) followed by radiotherapy between April 2013 and February 2022. The article does not report individual asbestos-exposure measurements. The authors calculated how much radiation reached the lung on the opposite side. They did this for the whole lung and for 'functional' lung, excluding emphysema-like areas seen on CT. Acute radiation pneumonitis, a radiation-related lung toxicity, developed in 42% of patients. The article reports 28% with moderate-to-severe (grade 2 to 3) cases without making clear whether this is 28% of all patients or of those with pneumonitis. The share of lung receiving at least 20 Gy (V20) was associated with pneumonitis (p = 0.017), as was its functional version (p = 0.028). Both predicted pneumonitis only moderately (AUC 0.668 and 0.655), and the functional measure was not significantly better. For grade 2 to 3 pneumonitis, a V20 cutoff of 1.8% had 47.3% sensitivity and 89.8% specificity. The authors concluded that conventional V20 is a robust predictor. They noted that data on lung disease and staging were incomplete.

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 single-center study
• Who was studied: 68 patients with non-metastatic malignant pleural mesothelioma treated with adjuvant radiotherapy after pleurectomy/decortication at IRCCS Humanitas Research Hospital, Milan, Italy, April 2013 to February 2022; median age 65 (range 37 to 78), majority male
• Exposure: Adjuvant intensity-modulated radiotherapy to 44 Gy, with a boost to a median of 50.6 Gy (range 50.6 to 59.4 Gy) at 1.8 to 2 Gy per fraction. Radiation dose to the contralateral lung (V20, V5, mean lung dose) was calculated for total and functional (emphysema-excluded) lung. The article does not report individual asbestos-exposure data; asbestos is mentioned only as background.
• Main results:
  • 42% of patients developed acute radiation pneumonitis; 28% had moderate-to-severe (grade 2 to 3) symptoms (the article does not make clear whether this is 28% of all patients or of those with pneumonitis)
  • Median contralateral lung V20 was 0.5%, V5 55%, and mean lung dose 6.25 Gy
  • Higher contralateral lung V20 was significantly associated with risk of pneumonitis (p = 0.017)
  • Functional contralateral lung V20 above 1% was significantly associated with increased risk of pneumonitis (p = 0.028)
  • Conventional V20 gave an AUC of 0.668 for predicting pneumonitis
  • Functional contralateral lung V20 gave an AUC of 0.655, with no significant improvement over conventional V20
  • Only V20 was significantly correlated with grade 2 to 3 pneumonitis; at a Youden-index cutoff of 1.8%, sensitivity was 47.3% and specificity 89.8%
• The authors' conclusion: The authors concluded that, while functional lung delineation provides an alternative in dosimetry, conventional V20 is a robust predictor of radiation pneumonitis.
• Limitations the authors state:
  • Data on pre-existing lung diseases were not systematically available for all patients and were not included in the analysis
  • Clinical TNM staging information was inconsistently available and was not considered

Topics

Medical terms in this study, explained in our Lexicon: Pneumonitis, Pleural Mesothelioma, Neoplasm, Asbestos Exposure, Pleurectomy/Decortication (P/D), Biomarker.

Related studies

• Dosimetric Correlates of Pulmonary Toxicity in Patients with Malignant Pleural Mesothelioma Receiving Radiation Therapy to the Intact Lungs — M.R. Thompson, V.A. Dumane, et al. (2019)
• Dosimetric Comparison of Lung-Sparing Radiation Therapy between Volumetric Arc Therapy and Helical Tomotherapy for Unresectable Malignant Pleural Mesothelioma — B. Pehlivan, K. Sengul, et al. (2019)
• Prediction of Radiation Pneumonitis With Machine Learning in Stage III Lung Cancer: A Pilot Study — M. Yakar, D. Etiz, et al. (2021)
• Radiation pneumonitis in a patient exposed to asbestos — R.F. Ashford, J. Maher, et al. (1981)
• A Multidisciplinary Approach to Improve the Management of Immune-Checkpoint Inhibitor-Related Pneumonitis — M. Valente, M. Colucci, et al. (2024)
• Spiroergometric parameters at maximal exercise testing assessed functional respiratory impairment in asbestos-induced fibrosis — J. Schneider, R. Arhelger, et al. (2014)

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