Prediction modelling using routine clinical parameters to stratify survival in Malignant Pleural Mesothelioma patients undergoing cytoreductive surgery

Our plain-English summary of Prediction modelling using routine clinical parameters to stratify survival in Malignant Pleural Mesothelioma patients undergoing cytoreductive surgery, by E.J.A. Harris, S. Kao, B. McCaughan, et al (Journal of Thoracic Oncology, 2019).

The study

• Authors: E.J.A. Harris, S. Kao, B. McCaughan, T. Nakano, N. Kondo, R. Hyland, A.K. Nowak, N.H. de Klerk, F.J.H. Brims
• Journal: Journal of Thoracic Oncology
• Published: 2019;14(2):288-293
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Malignant pleural mesothelioma (MPM) is an uncommon cancer with a poor prognosis and heterogeneous survival. Surgery for MPM is offered in some specialist centers to highly selected patients. A previously described classification and regression tree (CART) model stratified survival in unselected MPM patients using routinely collected clinical data. This study aimed to examine the performance of this CART model on a highly selected surgical population.

Methods: Data were collected from subjects undergoing cytoreductive surgery for MPM from specialist centers in Hyõgo, Japan, and Sydney, Australia, between 1991 and 2016. The CART model was applied using the combination of clinical variables to stratify subjects into risk groups (1 through 4); survival characteristics were then compared.

Results: Two hundred eighty-nine cases were included (205 from Australia, 84 from Japan). Overall median survival was 34.6 (interquartile range: 17.5-56.1) months; median age was 63.0 (interquartile range: 57.0-67.8) years, and 83.0% (n = 240) were male. There were no clinically meaningful differences between the two cohorts. Survival across the four risk groups was significantly different (p < 0.0001); the model stratified survival well with a Harrell's concordance statistic of 0.62 (95% confidence interval: 0.57-0.66) at 36 months. The group with the longest survival (median, 82.5 months) had: no weight loss, hemoglobin > 153 g/L and serum albumin > 43 g/L at time of referral to the surgical center.

Conclusions: Using routinely available clinical variables, the CART model was able to stratify surgical patients into risk groups with statistically different survival characteristics with fair to good performance. Presence of weight loss, anemia, and low albumin should confer caution when considering surgical therapy for MPM.

Copyright © 2018 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

In plain English

This study tested whether a previously published prediction tool (a decision-tree model called CART, built from routine clinical information) could sort patients with malignant pleural mesothelioma who had cytoreductive surgery into groups with different survival. The authors pooled 289 patients, 205 from Sydney, Australia and 84 from Hyogo, Japan, with data collected between 1991 and 2016. Most had extrapleural pneumonectomy (56.7%) or pleurectomy/decortication (30.4%). The study did not look at asbestos exposure. Survival differed across the four risk groups (p less than 0.0001). Group 1 was defined as no weight loss, hemoglobin above 153 g/L, and albumin above 43 g/L or not recorded. Its median survival was 82.5 months, against 22 months in group 4. The authors described the model's accuracy as fair-to-good. The authors concluded that weight loss, mild anemia and low-normal albumin should be considered when surgery is being decided. They noted that there was no comparison group without surgery, so the study does not show whether surgery works. They also noted that some data were missing.

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: Two-center cohort study applying a previously derived prediction model (CART decision tree) to surgical patients; most data collected prospectively, earlier cases retrospectively
• Who was studied: 289 patients with malignant pleural mesothelioma who completed surgical resection: 205 at Royal Prince Alfred Hospital/Strathfield Private Hospital, Sydney, Australia, and 84 at Hyogo College of Medicine, Japan; data collected 1991 to 2016; median age 63 years; 83.0% male
• Exposure: Asbestos exposure was not studied. The study examined routine clinical variables at referral (weight loss, hemoglobin, serum albumin, ECOG performance status, histologic subtype) in patients who had extrapleural pneumonectomy (56.7%), pleurectomy/decortication (30.4%), extended pleurectomy/decortication or partial pleurectomy
• Main results:
  • Risk group 1 (18 patients) had a median survival of 82.5 months (IQR 28.1 to 152.4). The Results text defines it as no weight loss, hemoglobin above 153 g/L and albumin above 43 g/L, but Table 2 lists albumin for group 1 as above 43 g/L or missing
  • Risk group 4 (68 patients, 23.9%) had a median survival of 22 months (IQR 10.1 to 41.9); survival differed across all four groups, p less than 0.0001 by log-rank test
  • Most patients in group 4 had no weight loss but had hemoglobin below 121 g/L
  • Risk group 2 had a median survival of 42.3 months
  • Risk group 3 was the largest group, holding the majority of patients (140, 48.4%), mainly because of weight loss or missing weight-loss data; its median survival was 35.2 months
  • Model performance (Harrell's c-statistic) was 0.62 at 36 months (CI 0.57 to 0.66) and 0.61 at 60 months (95% CI 0.57 to 0.64), which the authors called fair-to-good concordance
  • Weight loss (yes or missing) was the only baseline variable that differed between the centers: Japan 70 (83.3%) versus Australia 74 (36.1%), p = 0.001. Median survival did not differ between the two populations (p = 0.096)
  • Median survival did not differ significantly between patients with no weight loss (36.7 months) and those whose weight loss was not documented (39.4 months), p = 0.127
• The authors' conclusion: The authors concluded that the previously derived model could stratify fit, high-performance surgical patients, including a Japanese cohort, into distinct prognostic groups. They said clinicians considering surgery should incorporate weight loss, mild anemia and low-normal serum albumin into decision making, and that the model should be prospectively evaluated in future surgical studies
• Limitations the authors state:
  • There was no comparison group without surgery, so the study does not necessarily show that surgery is effective
  • Missing variables, including weight loss in the retrospectively collected cases; the authors state the model accounts for missing data
  • The surgical cohort differs from the unselected cohorts the model was derived on (age, performance status, histology), so comparisons need caution
  • Survival may differ slightly across the study population because treatment approaches differed

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Cytoreductive Surgery, Prognosis, Median Survival, confidence interval.

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