Individualized prediction of survival benefit from postoperative radiotherapy for patients with malignant pleural mesothelioma

Our plain-English summary of Individualized prediction of survival benefit from postoperative radiotherapy for patients with malignant pleural mesothelioma, by Y. Wo, Y. Peng, Z. Wu, et al (Cancer Medicine, 2023).

The study

• Authors: Y. Wo, Y. Peng, Z. Wu, P. Liu, Y. Shang, X. Shen, Y. Sun
• Journal: Cancer Medicine
• Published: 2023;12(11):12452-12461
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: The role of postoperative radiotherapy (PORT) in malignant pleural mesothelioma (MPM) remains controversial and the eighth edition TNM staging scheme for MPM has not been fully verified. We aimed to develop an individualized prediction model for identifying optimal candidates for PORT among MPM patients who received surgery plus chemotherapy and externally validate the performance of the new TNM staging scheme.

Materials And Methods: Detailed characteristics of MPM patients during 2004-2015 were retrieved from SEER registries. Propensity score matching (PSM) was conducted to reduce disparities of baseline characteristics (age, sex, histologic type, stage, and type of surgery) between the PORT group and no-PORT group. A novel nomogram was constructed based on independent prognosticators identified by multivariate Cox regression model. The discriminatory performance and degree of calibration were evaluated. We stratified patients into different risk groups according to nomogram total scores and estimated the survival benefit of PORT in different subgroups in order to identify the optimal candidates.

Results: We identified 596 MPM patients, among which 190 patients (31.9%) received PORT. PORT conferred significant survival benefit in the unmatched population, while there was no significant survival difference favoring PORT in the matched population. The C-index of the new TNM staging scheme was closed to 0.5, which represented a poor discriminatory ability. A novel nomogram was constructed based on clinicopathological factors, including age, sex, histology, and N stage. We stratified patients into three risk groups. Subgroup analyses indicated that PORT was beneficial for high-risk group (p = 0.003) rather than low-risk group (p = 0.965) and intermediate-risk group (p = 0.661).

Conclusion: We established a novel predictive model, which could make individualized prediction of survival benefit of PORT for MPM and could compensate for weakness in TNM staging system.

© 2023 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

In plain English

This retrospective study analyzed SEER cancer registry data on 596 patients with malignant pleural mesothelioma diagnosed 2004 to 2015. All were treated with surgery plus chemotherapy, and 190 also received postoperative radiotherapy (PORT). The study did not examine asbestos exposure. Before matching, median overall survival was 17 vs. 21 months (p = 0.025), favoring PORT. After matching 184 pairs of similar patients, the difference (19 vs. 21 months; p = 0.192) was not statistically significant. Age, sex, tumor cell type and lymph node stage independently predicted survival, and the authors combined them into a scoring tool (nomogram). Its C-index (how well it ranks survival) was 0.656 (95% confidence interval, CI, 0.623 to 0.688), versus 0.525 (95% CI 0.494 to 0.556) for eighth edition TNM staging. In the tool's high-risk group, PORT was associated with longer survival (p = 0.003). In the low-risk (p = 0.965) and intermediate-risk (p = 0.661) groups, no statistically significant survival difference was found. The authors concluded the model could help clinicians estimate PORT benefit. They noted PORT was not given in a randomized study and side effects could not be analyzed.

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 analysis of a population-based cancer registry (SEER), with propensity score matching and development of a survival prediction model (nomogram)
• Who was studied: 596 patients with malignant pleural mesothelioma diagnosed 2004 to 2015 in SEER registries, all treated with surgery plus chemotherapy; 190 (31.9%) also had postoperative radiotherapy and 406 (68.1%) did not
• Exposure: The exposure studied was a treatment: postoperative radiotherapy added to surgery plus chemotherapy, compared with surgery plus chemotherapy alone. Asbestos and fiber exposure were not studied.
• Main results:
  • In the unmatched population, PORT was associated with significantly longer survival (median overall survival 17 vs. 21 months; p = 0.025)
  • In the matched population (184 pairs), there was no significant survival difference favoring PORT (median overall survival 19 vs. 21 months; p = 0.192)
  • In multivariate analysis, age, sex, histologic subtype and N stage were independent predictors of overall survival
  • The nomogram had a C-index of 0.656 (95% CI 0.623 to 0.688)
  • The eighth edition TNM staging system had a C-index of 0.525 (95% CI 0.494 to 0.556), and the nomogram outperformed it (p less than 0.001)
  • Eighth edition TNM staging showed no significant survival difference between stage I and stage II (p = 0.210) or between stage II and stage III (p = 0.846)
  • There was no significant survival difference between any of the T descriptors in the SEER cohort
  • N0 patients had longer median overall survival than N1 patients (22 vs. 18 months; p = 0.043)
  • Risk groups were defined by nomogram score: high risk (score above 252), intermediate risk (between 96 and 241), and low risk (below 84)
  • PORT was associated with significantly longer overall survival in the high-risk group (p = 0.003)
  • No statistically significant survival difference with PORT was found in the low-risk group (p = 0.965) or the intermediate-risk group (p = 0.661)
• The authors' conclusion: The authors concluded that their prediction model discriminated survival better than the eighth edition TNM staging system and could help clinicians make individualized estimates of survival benefit from PORT
• Limitations the authors state:
  • PORT and chemotherapy were not given within a randomized study, and treatment intention was not recorded in detail
  • The lack of information on resection margin, performance status and complications could cause bias
  • SEER did not record detailed radiotherapy data, so adverse events of PORT could not be analyzed
  • Surgery could only be classified as radical or palliative, so extrapleural pneumonectomy could not be compared with pleurectomy decortication
  • Too few N2 cases were available to define the prognosis of N2 disease
  • There were too few non-epithelioid cases to build separate nomograms for each histologic subtype

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, TNM Staging, Chemotherapy, SEER, Histology.

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