Risk factors, prognostic factors, and nomograms for distant metastasis in patients with malignant pleural mesothelioma: A population-based retrospective study

Our plain-English summary of Risk factors, prognostic factors, and nomograms for distant metastasis in patients with malignant pleural mesothelioma: A population-based retrospective study, by Q. Lu, C. Liu, M. Xu, et al (The Journal of International Medical Research, 2025).

The study

• Authors: Q. Lu, C. Liu, M. Xu, Z. Hu, H. Yin, J. Yang
• Journal: The Journal of International Medical Research
• Published: 2025;53(10):3000605251389356
• Read it: PubMed · Publisher · Free full text

Abstract

ObjectivesMalignant pleural mesothelioma is a rare and aggressive thoracic tumor with a poor prognosis, wherein distant metastasis is associated with the lowest survival rates. It is imperative and emergent to construct nomograms based on risk factors and prognostic factors for distant metastasis in patients with malignant pleural mesothelioma.MethodsWe extracted data for the duration between 2010 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database and randomly categorized the patients into the training (70%) and validation (30%) cohorts. Risk factors for distant metastasis in patients with malignant pleural mesothelioma were identified using univariate and multivariate logistic regression analyses, and prognostic factors for patients with distant metastasis were determined using univariate and multivariate Cox regression analyses. Two nomograms were established based on the training cohort and evaluated using the validation cohort. The C-index, receiver operating characteristic curve, calibration curve, and decision curve analysis were used to assess the performance of the two nomograms.ResultsIn total, 2056 primary malignant pleural mesothelioma patients were included, and 341 patients were initially diagnosed with metastatic malignant pleural mesothelioma. Histology, laterality, grade, tumor stage, and node stage were independent risk factors for distant metastasis in patients with malignant pleural mesothelioma. Chemotherapy and metastasis to the lung, bone, and brain were independent prognostic factors for patients with malignant pleural mesothelioma and distant metastasis. The C-index values of the risk nomogram in the training and validation cohorts were 0.723 and 0.782, respectively. The C-index values of the prognostic nomogram in the training and validation cohorts were 0.678 and 0.712, respectively. The receiver operating characteristic curves, calibration curves, and decision curve analysis also demonstrated good predictive performance for the two nomograms in the training and validation cohorts.ConclusionsNomograms are useful and reliable tools for predicting distant metastatic risk in patients with malignant pleural mesothelioma and overall survival in patients with malignant pleural mesothelioma who had distant metastasis. These nomograms can provide strong references to clinicians to facilitate clinical decisions.

In plain English

This retrospective study used the US SEER cancer registry to examine 2056 patients with primary malignant pleural mesothelioma diagnosed 2010 to 2015. It did not study asbestos exposure. Of these, 341 (16.6%) had distant metastasis (spread to distant organs) at diagnosis. Median survival was 6 months with distant metastasis and 11 months without. Tumor grade, which side of the chest was affected, histology type, tumor (T) stage and lymph node (N) stage were independently associated with distant metastasis. In 228 training-group patients drawn from 327 with distant metastasis, chemotherapy versus none was associated with lower risk of death (HR 0.378, 95% CI 0.274–0.522). Lung, bone and brain metastasis were associated with higher risk of death (brain: HR 4.669, 95% CI 2.135–10.209). The authors built two prediction charts, called nomograms. The metastasis chart had a C-index of 0.782 (0.731–0.832) in a 617-patient validation group; the survival chart had 0.712 in a separate 99-patient validation group. The authors concluded the nomograms may help clinical decisions. Stated limitations were possible selection bias, US-only data without external validation, few metastatic patients, and incomplete tumor size and grade data.

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: Population-based retrospective study of cancer registry (SEER) data. Patients were randomly split 7:3 into training and validation cohorts to build and test two nomograms.
• Who was studied: 2056 patients with primary malignant pleural mesothelioma in the US SEER database, diagnosed 2010 to 2015. Of these, 341 had distant metastasis at diagnosis. The primary cohort was split into 1439 training and 617 validation patients. For the survival analysis, 327 patients with distant metastasis and complete treatment and metastasis-site data were split into 228 training and 99 validation patients.
• Exposure: Asbestos exposure was not studied. The variables examined were age, sex, race, grade, laterality, histology (biphasic, epithelioid, fibrous, not otherwise specified), tumor size, T and N stage, surgery, radiotherapy, chemotherapy, and metastasis to the lung, brain, bone and liver.
• Main results:
  • 341 of 2056 patients (16.6%) had distant metastasis at diagnosis. Median survival was 11 months for patients without distant metastasis and 6 months for those with it.
  • In multivariate logistic regression in the training cohort, bilateral tumors, higher grade, higher T stage, higher N stage and non-biphasic histology were independent risk factors for distant metastasis. The table labels these ratios HR: T4 vs non-T4 2.835 (95% CI 2.108–3.813); N3 vs N0 5.865 (2.985–11.523); grade III–IV vs I–II 8.303 (1.052–15.543); left vs bilateral 0.243 (0.091–0.647); right vs bilateral 0.252 (0.095–0.663); epithelioid vs biphasic 1.914 (1.058–3.464).
  • The diagnostic nomogram had a C-index of 0.723 (0.688–0.759) in the training cohort (1439 patients) and 0.782 (0.731–0.832) in the validation cohort (617 patients).
  • Survival analysis among patients with distant metastasis used Cox regression in the training cohort (228 of the 327 patients). Multivariate hazard ratios for death were: chemotherapy vs none 0.378 (0.274–0.522); lung metastasis 1.388 (1.042–1.847); bone metastasis 1.578 (1.15–2.166); brain metastasis 4.669 (2.135–10.209). Liver metastasis had no impact on survival.
  • The prognostic nomogram had a C-index of 0.678 in the training cohort and 0.712 in the validation cohort; no confidence intervals were given. AUCs at 6, 12 and 18 months were 0.722, 0.728 and 0.759 in training and 0.804, 0.711 and 0.812 in validation.
• The authors' conclusion: The authors concluded that grade, laterality, histology, T stage and N stage are independent risk factors for distant metastasis. They concluded that chemotherapy and metastasis to the lung, bone and brain are independent prognostic factors. They also concluded that the two nomograms may be clinically useful for assessing risk and prognosis.
• Limitations the authors state:
  • Possible selection bias in a retrospective study; prospective studies are needed to confirm the results.
  • SEER data come only from the US population, and the model lacked external validation.
  • The small number of patients with distant metastasis may have caused inaccuracy.
  • Tumor size and grade data were incomplete, which may underestimate their impact.

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: Metastasis, Pleural Mesothelioma, Prognosis, Epidemiology, SEER, Histology, Chemotherapy, Overall Survival.

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