Prophylactic procedure tract radiotherapy for malignant pleural mesothelioma: A systematic review and meta-analysis

Our plain-English summary of Prophylactic procedure tract radiotherapy for malignant pleural mesothelioma: A systematic review and meta-analysis, by S. Bergamin, M. Tio, M.J. Stevens (Clinical and Translational Radiation Oncology, 2018).

The study

• Authors: S. Bergamin, M. Tio, M.J. Stevens
• Journal: Clinical and Translational Radiation Oncology
• Published: 2018;13:38-43
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background And Purpose: Malignant pleural mesothelioma (MPM) is an aggressive cancer with a propensity for seeding procedure tracts, leading to symptomatic metastases. There is conflicting evidence on the value of prophylactic procedure tract radiotherapy in reducing tract metastases. We performed a systematic review and meta-analysis to estimate the benefit of radiotherapy in this setting.

Materials And Methods: Electronic databases were searched to January 1, 2018 for prospective randomized control trials with prophylactic procedure tract radiotherapy as the intervention arm. Pooled odds ratios and 95% confidence intervals were calculated using a random effects model. Study heterogeneity was assessed using the I2 statistic, and publication bias was evaluated by funnel plot and Egger's regression model.

Results: Five studies were included for meta-analysis. Prophylactic radiotherapy did not have a statistically significant reduction on the risk of procedure site recurrence, with a pooled relative risk of 0.69 (95% CI 0.33-1.43). There was moderate heterogeneity between trials. All trials were assessed as moderate or high risk of bias overall.

Conclusion: This systematic review has confirmed that there is no role for prophylactic procedure tract radiotherapy in MPM. In the absence of effective prophylactic procedures, patients need to be monitored closely, and palliative interventions delivered in a timely manner to reduce morbidity associated with procedure tract metastases.

In plain English

This article was a systematic review and meta-analysis, not a new trial. The authors searched medical databases and trial registries up to January 2018 for randomized controlled trials. They looked for trials that compared preventive (prophylactic) radiotherapy with no such radiotherapy. The radiotherapy was aimed at the sites where needles, drains or surgical instruments had entered the chest of people with malignant pleural mesothelioma. Five trials with 737 patients in total were included, and one had been reported only as an abstract. Four trials gave 21 Gy in three fractions, and one gave 10 Gy in a single fraction. When the trials were combined, preventive radiotherapy did not produce a statistically significant reduction in cancer recurrence at procedure sites (pooled relative risk 0.69, 95% CI 0.33 to 1.43, p = 0.32). Differences between the trials were moderate, and all trials were judged at moderate or high risk of bias. Survival, side effects and quality of life were not pooled because the trials reported them differently. The authors concluded that there is no role for this radiotherapy. They noted remaining uncertainty about whether some subgroups might benefit.

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: Systematic review and meta-analysis of randomized controlled trials
• Who was studied: 5 randomized controlled trials of malignant pleural mesothelioma patients who had chest procedures, 737 patients in total. Databases and trial registries were searched from inception to January 2018. One trial was reported in abstract form only.
• Exposure: Not an asbestos exposure study. The intervention was prophylactic radiation therapy to procedure tract sites, compared with no prophylactic radiation therapy or sham radiation. Four trials used 21 Gy in three fractions; one used 10 Gy in a single fraction with 9 MeV electrons.
• Main results:
  • Across all 5 trials, prophylactic radiation therapy did not produce a statistically significant reduction in procedure site recurrence: pooled relative risk 0.69 (95% CI 0.33–1.43), p = 0.32.
  • Heterogeneity between trials was moderate (I2 = 41.0).
  • No evidence of publication bias was found on visual inspection or Egger's test (p = 0.69).
  • All included trials were assessed as moderate or high risk of bias overall.
  • Only one trial reported a grade 3 adverse event (a single case of radiation dermatitis); the other trials reported grade 2 or lower adverse events only.
  • Survival, adverse events and quality of life were not meta-analysed because the trials reported them differently.
• The authors' conclusion: The authors concluded that their review confirmed there is no role for prophylactic procedure tract radiation therapy in malignant pleural mesothelioma. They stated that uncertainty remains about whether certain subgroups benefit, and that patients need close monitoring and prompt management of symptoms.
• Limitations the authors state:
  • Radiation therapy dose, technique and timing varied across the included trials.
  • No trial used modern CT-simulation to define target volumes, which may limit applicability to current clinical practice.
  • None of the trials was powered to determine whether certain subgroups would benefit.
  • One included trial had been reported in abstract form only.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Systematic Review, Meta-Analysis, Odds Ratio, confidence interval, Relative Risk, Palliative Care.

Related studies

• Prophylactic radiotherapy for the prevention of procedure-tract metastases after surgical and large-bore pleural procedures in malignant pleural mesothelioma (SMART): a multicentre, open-label, phase 3, randomised controlled trial — A.O. Clive, H. Taylor, et al. (2016)
• Protocol for the surgical and large bore procedures in malignant pleural mesothelioma and radiotherapy trial (SMART Trial): an RCT evaluating whether prophylactic radiotherapy reduces the incidence of procedure tract metastases — A.O. Clive, P. Wilson, et al. (2015)
• Prophylactic radiotherapy to prevent procedure-tract metastases — G. Zalcman, S. Brosseau, et al. (2016)
• Prophylactic radiotherapy for procedure tract metastases in mesothelioma: a review — D.T. Arnold, A.O. Clive (2017)
• Prophylactic radiotherapy to prevent procedure-tract metastases — D. Landau, E. Lim (2016)
• Prophylactic irradiation of tracts in patients with malignant pleural mesothelioma: A systematic review and meta-analysis of randomized trials — C.C. Lee, Y.Y. Soon, et al. (2021)

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