Specimen weight and volume: important predictors of survival in malignant pleural mesothelioma

Our plain-English summary of Specimen weight and volume: important predictors of survival in malignant pleural mesothelioma, by D.Y. Kircheva, A.N. Husain, S. Watson, et al (European Journal of Cardio-thoracic Surgery, 2016).

The study

• Authors: D.Y. Kircheva, A.N. Husain, S. Watson, H.L. Kindler, A. Durkin, W.T. Vigneswaran
• Journal: European Journal of Cardio-thoracic Surgery
• Published: 2016;49(6):1642-7
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: The tumour/node/metastasis (TNM) staging system for malignant pleural mesothelioma (MPM) is a worldwide standard, but has many limitations. Tumour volume has been suggested as a predictor of survival. Due to the complex anatomy, estimation of tumour volume via CT scan can be challenging. Surgical volume may be more accurate. Therefore, we prospectively determined resected specimen volumes and weights in consecutive patients undergoing extended pleurectomy and decortication (EPD) and correlated this with overall survival and T and N stage.

Methods: We evaluated 116 patients undergoing EPD for MPM in a single university centre over a 6-year period. All resected specimens were weighed, and the volume was measured by a fluid displacement method. A Cox regression model was used to identify significant predictors of survival; hazard ratios were calculated. A Kaplan-Meier method was used to summarize overall and subgroup survival. Logistic regression models were used to identify predictors of T and N stage.

Results: There were 95 males and 21 females with a median age of 68 range 43-88 years. Forty-one patients had an ECOG performance status (PS) 0, 70 had 1 and 4 had 2. The median time between initial diagnosis and surgery was 134 days. Histology was epithelioid in 59, biphasic in 55 and sarcomatoid in 2. The mean volume was 641 ml with an SD of 393.34 ml. The median volume was 567.5 ml. The mean weight was 620.8 g with an SD of 361.92 g. The median weight was 552.0 g. Two-year survival from initial diagnosis and from EPD was 44 and 28%, respectively. PS (P = 0.002), epithelioid histology (P < 0.001), specimen weight (P < 0.001), volume (P < 0.001), platelet count (P = 0.015), T1 stage (P = 0.04) and adjuvant therapy (P = 01) were predictive of survival. Tumour volume was a predictor of T stage (P = 0.048) and survival (P = 0.03). There was no relationship between N stage and tumour volume, weight or histology.

Conclusions: PS, specimen weight, volume, epithelioid histology platelet count and adjuvant chemotherapy are significant predictors of survival in patients undergoing EPD for MPM. There is a correlation between specimen volume and T stage. These data suggest that tumour weight and volume may be valuable components for staging MPM.

© The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

In plain English

This study followed 116 consecutive patients with malignant pleural mesothelioma who had a surgery called extended pleurectomy and decortication at one university centre in Chicago between March 2008 and November 2014. The pathologist weighed the removed tissue and measured its volume by water displacement. The authors then compared these measurements with how long patients survived. The median specimen volume was 567.5 ml. Patients whose specimen was larger than this median had a median survival of 11.88 months, compared with 22.56 months for those below it. In the multivariable analysis, the factors linked to survival were performance status (a measure of how well patients function day to day), adjuvant chemotherapy, tumour volume and T1 stage. Lymph-node (N) stage was not statistically significant. The authors concluded that specimen volume and weight were significant predictors of survival, and that using them in staging needs further validation in larger multicentre studies. They noted that the study was comparatively small and that removed tissue may include fat or muscle. The article does not discuss 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-centre study of consecutive surgical patients, with clinical data entered prospectively into an institutional database and analysed for predictors of survival
• Who was studied: 116 consecutive patients with biopsy-proven malignant pleural mesothelioma who underwent extended pleurectomy and decortication at a single centre (University of Chicago) between March 2008 and November 2014. Most were male (95 men, 21 women). By histology, 59 were epithelioid, 55 biphasic and 2 sarcomatoid.
• Exposure: The article does not report asbestos exposure. The factors studied were the volume and weight of the tissue removed at surgery. Volume was measured by water displacement before fixation. Other factors examined included performance status, histology, platelet count, and T and N stage.
• Main results:
  • Median specimen volume was 567.5 ml (range 100 to 2200 ml). Median specimen weight was 552.0 g.
  • For all patients, median survival was 22.9 months from diagnosis and 15.5 months after surgery. Two-year survival was 48.3% from diagnosis and 31.5% from surgery.
  • Patients with specimen volume above 567.5 ml had a median survival of 11.88 months, versus 22.56 months for those below 567.5 ml (P less than 0.001).
  • Median survival by volume subgroup was 26.94 months (under 300 ml), 19.45 months (301 to 600 ml), 12.68 months (601 to 900 ml) and 11.07 months (over 900 ml), with P less than 0.001.
  • In the multivariable analysis, the significant predictors of survival were performance status, adjuvant chemotherapy, tumour volume and T1 stage.
  • N (lymph node) stage was not statistically significant for survival in this study.
  • Tumour volume and tumour weight were highly correlated (0.97), so weight was left out of the multivariable model.
  • Neoadjuvant therapy (treatment given before surgery) did not affect tumour volume or weight measurements (P = 0.37 and 0.90).
• The authors' conclusion: The authors concluded that specimen volume and weight were significant predictors of survival after this surgery, as important as histological type or performance status. They added that using these measures in staging and clinical decision-making needs further validation in larger multicentre studies.
• Limitations the authors state:
  • Measuring the removed specimen has limits, because the tissue may include extraneous tissue such as fat or muscle removed along with the tumour.
  • Pathological volume was measured only in 25 ml increments.
  • The sample size was comparatively small, so the authors said they could not draw definitive conclusions about T and N stage.
  • Adjuvant therapy was given to patients who did well after surgery, which creates a selection bias in favour of that group.
  • Specimen volume was not measured in 6 patients.

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, Metastasis, Staging, CT Scan, Overall Survival, Hazard Ratio, ECOG Performance Status, Histology.

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• Lung volume measurements as a surrogate marker for patient response in malignant pleural mesothelioma — Z.E. Labby, S.G. Armato, et al. (2013)
• Important prognostic factors in patients with malignant pleural mesothelioma, managed surgically — V.W. Rusch, E.S. Venkatraman (1999)

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