Establishment and validation of nomograms to predict survival probability of advanced malignant pleural mesothelioma based on the SEER database and a Chinese medical institution

Our plain-English summary of Establishment and validation of nomograms to predict survival probability of advanced malignant pleural mesothelioma based on the SEER database and a Chinese medical institution, by X. Zhang, L. Chang, Y. Zhu, et al (Frontiers in Endocrinology, 2023).

The study

• Authors: X. Zhang, L. Chang, Y. Zhu, Y. Mao, T. Zhang, Q. Zhang, C. Wang
• Journal: Frontiers in Endocrinology
• Published: 2023;14:1139222
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: The purpose of this study was to build nomograms for predicting the survival of individual advanced pleural mesothelioma (MPM) patients using the Surveillance, Epidemiology, and End Results (SEER) database.

Methods: The 1251 patients enrolled from the SEER database were randomized (in a 7:3 ratio) to a training cohort and an internal validation cohort. Eighty patients were enrolled from the Harbin Medical University Cancer Hospital as the external validation cohort. Nomograms were constructed from variables screened by univariate or multivariate Cox regression analyses and evaluated by consistency indices (C-index), calibration plots, and receiver operating characteristic (ROC) curves. Patients from the SEER database who received chemotherapy alone and chemoradiotherapy were statistically paired using propensity score matching of the two groups and performed subgroup analysis in the screened variables.

Results: The nomograms are well-structured and well-validated prognostic maps constructed from four variables: gender, histology, AJCC stage, and treatment. All individuals were allocated into high-risk versus low-risk groups based on the median risk score of the training cohort, with the high-risk group having worse OS and CSS in all three cohorts (P<0.05). The outcomes of the subgroup analysis indicated that the advanced MPM patients receiving chemotherapy with or without local radiotherapy do not affect OS or CSS.

Conclusion: The accurate nomograms to predict the survival of patients with advanced MPM were built and validated based on an analysis of the SEER database with an external validation cohort. The study suggests that the additional local radiotherapy to chemotherapy does not increase the survival benefit of patients.

Copyright © 2023 Zhang, Chang, Zhu, Mao, Zhang, Zhang and Wang.

In plain English

This retrospective study looked at advanced malignant pleural mesothelioma (stage IIIB or IV) in people who did not have surgery. The authors took 1,251 patients diagnosed from 2005 to 2018 from the US SEER cancer database and split them into training (879) and checking (372) groups. They tested their tools on 80 patients who attended Harbin Medical University Cancer Hospital in China from 2010 to 2018. The tools were nomograms: charts that estimate a patient's chance of surviving 6 months, 1 year and 2 years. They were built from gender, tumor cell type (histology), stage and treatment. For overall survival, the charts' C-index, a measure of how well they rank patients by survival, was 0.656 (95% CI 0.636-0.677), 0.668 (0.634-0.701) and 0.684 (0.605-0.763) in the three groups. Patients placed in the charts' high-risk group had significantly worse survival. In 104 matched pairs of SEER patients, those given chemotherapy alone tended to do better than those also given radiotherapy, but no difference was statistically significant. The authors concluded that adding radiotherapy did not improve survival. The study did not examine 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 study building and validating survival prediction charts (nomograms) from registry data, with external validation in a hospital cohort and a propensity-score-matched comparison of treatments
• Who was studied: 1251 patients with stage IIIB or IV malignant pleural mesothelioma diagnosed 2005-2018 in the US SEER database who did not undergo surgery (training cohort n = 879, internal validation cohort n = 372; 974, or 77.9%, male). An external validation cohort of 80 patients who attended Harbin Medical University Cancer Hospital, China, 2010-2018.
• Exposure: Asbestos or fiber exposure was not studied. The factors examined were patient and tumor characteristics and treatment: chemotherapy alone, chemoradiotherapy, or radiotherapy alone.
• Main results:
  • In the training cohort, four factors were kept as independent predictors of survival: gender, histology, AJCC stage and treatment. Age was significant in the univariate analysis but was excluded from the final model.
  • In the multivariate analysis of overall survival in the training cohort, the hazard ratios were as follows. Women compared with men: 0.80 (95% CI 0.67-0.95). Stage IV compared with stage IIIB: 1.37 (1.19-1.57). Fibrous compared with not-otherwise-specified histology: 1.64 (1.33-2.01). Epithelioid compared with not-otherwise-specified histology: 0.80 (0.68-0.94).
  • In the training cohort, chemotherapy alone compared with chemoradiotherapy had a multivariate hazard ratio for overall survival of 0.81 (95% CI 0.62-1.08), P = 0.15. No or unknown treatment had a hazard ratio of 1.42 (1.06-1.89), P = 0.02.
  • The C-index (a measure of how well the model ranks patients by survival) of the overall-survival model was 0.656 (95% CI 0.636-0.677) in the training cohort, 0.668 (95% CI 0.634-0.701) in the internal validation cohort and 0.684 (95% CI 0.605-0.763) in the external validation cohort. The cancer-specific survival model had C-indexes of 0.654, 0.657 and 0.754 in the same cohorts.
  • Patients were split into high-risk and low-risk groups at the training cohort's median risk score. Overall and cancer-specific survival differed significantly between these groups.
  • Two-year survival was lower in men than in women in all three cohorts: 8.9% vs. 16.1% in the training cohort, 9.6% vs. 18.6% in the internal validation cohort, and 17.9% vs. 52.7% in the external validation cohort.
  • In 104 propensity-matched pairs of SEER patients (208 in total), the chemotherapy-only group tended to have better overall and cancer-specific survival than the chemoradiotherapy group in all subgroups. None of these results reached statistical significance.
• The authors' conclusion: The authors concluded that they had built and validated two nomograms to predict survival in advanced MPM. They also concluded that chemotherapy is the main treatment and that adding radiotherapy did not improve the probability of survival.
• Limitations the authors state:
  • The SEER database lacks the specific regimens and timing of chemotherapy and radiotherapy.
  • Many SEER variables contain large numbers of unknowns, which may confound the results.
  • The SEER database has no information on immunotherapy.
  • Because the external sample was small, the treatment subgroup analysis used only SEER patients and was not validated with real-world data.
  • SEER patients are mostly from earlier years, when radiotherapy techniques were outdated.
  • The external validation group was small and differed from the SEER patients, which may have biased results.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, SEER, Epidemiology, Chemotherapy, Histology, AJCC.

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