Percutaneous Cryoablation for the Treatment of Recurrent Malignant Pleural Mesothelioma: Safety, Early-Term Efficacy, and Predictors of Local Recurrence

Our plain-English summary of Percutaneous Cryoablation for the Treatment of Recurrent Malignant Pleural Mesothelioma: Safety, Early-Term Efficacy, and Predictors of Local Recurrence, by F. Abtin, M.T. Quirk, R.D. Suh, et al (Journal of Vascular and Interventional Radiology, 2017).

The study

• Authors: F. Abtin, M.T. Quirk, R.D. Suh, W. Hsu, S.X. Han, G.J. Kim, S. Genshaft, J.K. Sandberg, O. Olevsky, R.B. Cameron
• Journal: Journal of Vascular and Interventional Radiology
• Published: 2017;28(2):213-221
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: To determine safety and early-term efficacy of CT-guided cryoablation for treatment of recurrent mesothelioma and assess risk factors for local recurrence.

Materials And Methods: During the period 2008-2012, 24 patients underwent 110 cryoablations for recurrent mesothelioma tumors in 89 sessions. Median patient age was 69 years (range, 48-82 y). Median tumor size was 30 mm (range, 9-113 mm). Complications were graded using Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0). Recurrence was diagnosed on CT or positron emission tomography/CT by increasing size, nodular enhancement, or hypermetabolic activity and analyzed using the Kaplan-Meier method. Cox proportional hazards model was used to determine covariates associated with local tumor recurrence.

Results: Median duration of follow-up was 14.5 months. Complications occurred in 8 of 110 cryoablations (7.3%). All but 1 complication were graded CTCAE v4.0 1 or 2. No procedure-related deaths occurred. Freedom from local recurrence was observed in 100% of cases at 30 days, 92.5% at 6 months, 90.8% at 1 year, 87.3% at 2 years, and 73.7% at 3 years. Tumor recurrence was diagnosed 4.5-24.5 months after cryoablation (mean 5.7 months). Risk of tumor recurrence was associated with a smaller ablative margin from the edge of tumor to iceball ablation margin (multivariate hazard ratio 0.68, CI 0.48-0.95, P = .024).

Conclusions: CT-guided cryoablation is safe for local control of recurrent mesothelioma, with a low rate of complications and promising early-term efficacy. A smaller ablative margin may predispose to tumor recurrence.

Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

In plain English

This single-center retrospective review examined CT-guided cryoablation, which freezes tumors using probes passed through the skin, in patients with recurrent malignant pleural mesothelioma, nearly all after prior surgery. From 2008 to 2012, 24 patients had 110 tumors treated in 89 sessions: 95 tumors in 19 patients for tumor control and 15 tumors in 5 patients for symptom relief. Complications followed 8 of 110 procedures (7.3%). One was a grade 3 rib bone infection with abscess; no treatment-related deaths occurred. Of 95 tumors treated for control, 9 recurred at the treated site. The rate free of local recurrence was 90.8% at 1 year and 73.7% at 3 years. The tumor-to-iceball margin, measured in millimeters, was the only factor significantly linked to recurrence (multivariate hazard ratio 0.68, CI 0.48–0.95); on univariate analysis, each 1 mm increase above the median 6.4 mm reduced recurrence risk by approximately 35%. The authors concluded that cryoablation appeared safe, with promising early results. They noted they did not study survival and recurrences were diagnosed by imaging without biopsy. The article does not report 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: Single-center retrospective review of treated patients (case series); no comparison group
• Who was studied: 24 patients with recurrent malignant pleural mesothelioma treated 2008–2012 at the authors' institution (authors based at University of California, Los Angeles). There were 110 tumors treated in 89 sessions. 19 patients with 95 tumors were treated for local tumor control, and 5 patients with 15 tumors for symptom relief (palliation). Median age was 69 years (range 48–82). Most had prior pleurectomy/decortication. Table 1 lists 1 palliative patient with no prior surgery.
• Exposure: The intervention studied was CT-guided percutaneous cryoablation (argon-based freezing) of recurrent tumors, with a planned ablative margin of 5 mm. The article reports no information on asbestos or other fiber exposure.
• Main results:
  • Complications occurred in 8 of 110 cryoablation procedures (7.3%). All but 1 were CTCAE grade 1 or 2. No procedure-related deaths occurred.
  • The one grade 3 complication was rib osteomyelitis and soft tissue abscess (Staphylococcus aureus). It was treated with intravenous antibiotics and surgical débridement.
  • Technical success (planned ablation completed with tumor within the ablation zone) was achieved in 95 of 95 cryoablations performed for local control.
  • In the local control cohort, local tumor recurrence was diagnosed in 9 of 95 tumors. Recurrence was diagnosed 4.5–24.5 months after cryoablation (mean 5.7 months).
  • Freedom from local recurrence for tumors treated for local control was 100% at 30 days, 92.5% at 6 months, 90.8% at 1 year, 87.3% at 2 years, and 73.7% at 3 years.
  • Of the 92 tumors with PET/CT follow-up, 83 (90.2%) showed no evidence of recurrence over the follow-up period.
  • Ablative margin from tumor edge to iceball edge, measured in millimeters, was the only covariate significantly associated with recurrence. Univariate hazard ratio was 0.65, CI 0.45–0.92, P = .016. Multivariate hazard ratio was 0.68, CI 0.48–0.95, P = .024. Hazard ratios below 1 mean that a larger margin went with lower recurrence risk.
  • On univariate analysis, each 1 mm increase above the median margin of 6.4 mm reduced recurrence risk by approximately 35%. No recurrence was seen when the iceball margin was greater than 8.9 mm.
  • Recurrence differed significantly between tumors with an iceball margin of 5 mm or more and those with a margin under 5 mm (log-rank P = .0058).
• The authors' conclusion: The authors concluded that CT-guided cryoablation is safe for local control of recurrent mesothelioma, with a low complication rate and promising early-term efficacy. They concluded that a smaller ablative margin may predispose to recurrence, and that further study of its effect on overall survival is warranted.
• Limitations the authors state:
  • The study did not directly examine patient survival. Any effect of cryoablation on progression-free or overall survival remains speculative.
  • Separating patients into palliative and local control cohorts may have introduced selection bias.
  • Recurrence was diagnosed by imaging only, without tissue biopsy, so some tumors could be false positives.
  • Variable imaging schedules and methods (CT vs PET/CT) may have affected detection of complications and recurrence. Some recurrences may have been missed.
  • Adjuvant chemotherapy in some patients may have affected recurrence rates.
  • The retrospective design and small number of patients limit generalizability.

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, Mesothelioma, Hazard Ratio.

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