Role of postoperative radiotherapy in the management of malignant pleural mesothelioma : A propensity score matching of the SEER database

Our plain-English summary of Role of postoperative radiotherapy in the management of malignant pleural mesothelioma : A propensity score matching of the SEER database, by O. Abdel-Rahman (Strahlentherapie und Onkologie, 2017).

The study

• Author: O. Abdel-Rahman
• Journal: Strahlentherapie und Onkologie
• Published: 2017;193(4):276-284
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: This study assessed the prognostic impact of postoperative radiotherapy in patients with surgically resected malignant pleural mesothelioma (MPM).

Methods: MPM patients diagnosed between 2000 and 2013 were identified from the SEER (Surveillance, Epidemiology, and End Results) database. A propensity-matched analysis was performed considering baseline characteristics (age, gender, race, histology, TNM stage, and type of surgery).

Results: A total of 2166 patients were identified. The median age was 60 years (range 25-85 years), and 469 patients received postoperative radiotherapy. Both before and after propensity score matching, overall survival (P < 0.0001 and P = 0.012, respectively) was better in the postoperative radiotherapy group. When the overall survival was stratified by histology, postoperative radiotherapy did not improve the survival in sarcomatoid histology patients both before and after matching (P = 0.424 and P = 0.281, respectively). In multivariate analysis of the matched population, not receiving postoperative radiotherapy did not correlate with worse survival (hazard ratio: 1.175; P = 0.12). Factors associated with worse survival include sarcomatoid histology, nodal positivity, and age ≥70.

Conclusion: Evidence from this analysis is insufficient on its own to routinely recommend postoperative radiotherapy for surgically resected MPM. However, large-scale prospective clinical trials are warranted to further evaluate this intervention in nonsarcomatoid histology.

In plain English

Using the US SEER cancer registry, the author asked whether radiotherapy after surgery was linked to longer survival in malignant pleural mesothelioma. The study included 2166 patients aged 20 or older, diagnosed 2000 to 2013, who had surgery; 469 also received postoperative radiotherapy. Because treatment was not randomized, these 469 were matched one-to-one with 469 similar patients who did not receive it. In the matched groups, overall survival was better with radiotherapy (P = 0.012; median 18 versus 13 months). However, among patients surviving more than 3 months there was no survival benefit (P = 0.992), and sarcomatoid tumors showed no benefit. In multivariate analysis, not receiving radiotherapy was not significantly linked to worse survival (hazard ratio 1.175, 95% CI 0.959 to 1.439). Sarcomatoid histology, lymph node involvement and age 70 or older were linked to worse survival. The author concluded the evidence was insufficient on its own to routinely recommend postoperative radiotherapy. The registry lacked information on radiotherapy technique, chemotherapy and side effects. Asbestos exposure was not studied.

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 national cancer registry (SEER), with propensity score matching (nearest neighbor, 1:1) of patients who did and did not receive postoperative radiotherapy
• Who was studied: 2166 patients aged 20 years or older in the US SEER registries, diagnosed with malignant pleural mesothelioma from 2000 to 2013, who had surgery. Median age was 60 years (range 25 to 85), 1713 were male, and more than 90% were white.
• Exposure: Postoperative radiotherapy (PORT) after surgical resection, compared with surgery without PORT. The registry gave no radiotherapy technique, volume or dose details and no chemotherapy information. Asbestos exposure was not studied.
• Main results:
  • Before matching (all 2166 patients, of whom 1440 had died), overall survival favored the postoperative radiotherapy group (P < 0.0001).
  • Before matching, by histology: a statistically significant benefit was reported for the epithelioid subgroup (P < 0.0001) and the biphasic subgroup (printed as P < 0.017), and no benefit for the sarcomatoid subgroup (P = 0.424).
  • Matching produced 469 patients with postoperative radiotherapy and 469 without.
  • In the matched population, overall survival was better in the postoperative radiotherapy group (P = 0.012).
  • Median survival in the matched population was 18 months with postoperative radiotherapy and 13 months without.
  • In a sensitivity analysis limited to patients who survived more than 3 months, postoperative radiotherapy showed no survival benefit (P = 0.992).
  • After matching, the author described the nonsarcomatoid subgroup as approaching statistical significance (P = 0.020).
  • In sarcomatoid histology patients, postoperative radiotherapy did not improve survival either before matching (P = 0.424) or after matching (P = 0.281).
  • In multivariate analysis of the matched population, not receiving postoperative radiotherapy was not significantly associated with worse overall survival (hazard ratio 1.175, 95% CI 0.959 to 1.439, P = 0.12).
  • In the multivariate analysis of the matched population, sarcomatoid histology (P < 0.0001), lymph node involvement (P = 0.001) and age 70 or older (P < 0.0001) were associated with worse overall survival.
  • In the matched population, cancer-specific survival showed no statistically significant benefit for postoperative radiotherapy (P = 0.601).
• The authors' conclusion: The author concluded that the evidence from this analysis is insufficient on its own to routinely recommend postoperative radiotherapy for surgically resected malignant pleural mesothelioma. The author added that large prospective trials may be warranted in nonsarcomatoid histology.
• Limitations the authors state:
  • Patients were not randomized, so baseline differences could have caused selection bias.
  • SEER lacks information on radiotherapy technique and on whether, and what, chemotherapy was given.
  • Some cases of prophylactic tract radiotherapy may have been mistaken for formal hemithoracic radiotherapy, which complicates interpretation.
  • Toxicity of postoperative radiotherapy is not reported in SEER.
  • Because the disease is so deadly, cancer-specific survival is of limited use.
  • The univariate and multivariate analyses included only patients with complete data.

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, SEER, Epidemiology, Histology, Overall Survival, Sarcomatoid, Multivariate Analysis, Hazard Ratio.

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