Diffuse malignant mesothelioma of the pleura in Ontario and Quebec: a retrospective study of 332 patients

Our plain-English summary of Diffuse malignant mesothelioma of the pleura in Ontario and Quebec: a retrospective study of 332 patients, by P. Ruffie, R. Feld, S. Minkin, et al (Journal of Clinical Oncology, 1989).

The study

• Authors: P. Ruffie, R. Feld, S. Minkin, Y. Cormier, A. Boutan-Laroze, R. Ginsberg, J. Ayoub, F.A. Shepherd, W.K. Evans, A. Figueredo
• Journal: Journal of Clinical Oncology
• Published: 1989;7(8):1157-68
• Cited by: 275 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000152).

Abstract

Three-hundred thirty-two cases of pleural diffuse malignant mesothelioma (DMM) seen at large centers in Ontario and Quebec from 1965 to 1984 were reviewed retrospectively. Previous asbestos exposure was found in 44% of patients. Diagnosis was most often made by exploratory thoracotomy; pleural biopsy or cytology were rarely contributory. The delay in diagnosis was often long (median time, 3.5 months) and thrombocytosis (platelets greater than or equal to 400,000/microL) was common (41% of cases). The median survival (MS) was only 9 months. Eleven clinical variables were analyzed for prognostic significance. The three most important prognostic factors using a univariate analysis were stage, weight loss, and histologic type. For 118 patients with complete data, multivariate analysis showed that the stage of disease, high platelet count, and asbestos exposure were the most important prognostic factors. There was no cure of DMM, and we did not find any drastic differences in survival among groups of patients subjected to the different therapeutic measures. Radical surgery and radiotherapy were ineffective and we confirmed the low response rate to chemotherapeutic agents. This large retrospective trial can serve as a baseline for future studies in this field. In particular, it provides the basis for appropriate stratification variables to be used in future therapeutic trials.

In plain English

This was a retrospective review of hospital charts for 332 patients with diffuse malignant mesothelioma of the pleura (the lining of the lungs). The patients were seen at large centers in Ontario and Quebec from 1965 to 1984; 262 were men and 70 were women. Charts recorded previous asbestos exposure in 145 patients (44%). Among the 245 patients with exposure information, 59% were classified as definite or probable. Exposure was recorded more often in men than in women (68% versus 18%). Among exposed patients, the time from first exposure to symptoms ranged from 19 to 45 years (median 32 years). Median survival was 9 months. In 118 patients with complete data, stage of disease, a high platelet count and asbestos exposure were the factors most strongly linked to survival. A high platelet count and asbestos exposure were associated with shorter survival. Patients given chemotherapy lived longer (median 12.3 versus 7.3 months), but the authors said this may not be due to the chemotherapy itself. Survival did not differ significantly by type of surgery. The authors concluded there was no cure and that the series could serve as a baseline for future studies.

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 multicenter review of patient charts
• Who was studied: 332 patients with pleural diffuse malignant mesothelioma registered at participating centers in Ontario (131) and Quebec (201) from 1965 to 1984. There were 262 men and 70 women, with a mean age of 59 years. They were selected from 396 patients with a pathological diagnosis of DMM at any site.
• Exposure: Previous asbestos exposure as recorded in the charts. It was classified as definite, probable (by occupation, such as insulation, mining or milling, manufacturing, heating trades, shipyard work and construction), unlikely, or undetermined. Exposure was recorded as yes in 145 patients (44%), no in 100 (30%) and unknown in 87 (26%). Duration of exposure ranged from 3 months to over 35 years (median 12 years). No fiber types are named.
• Main results:
  • Of the 245 patients with information on asbestos exposure, 59% were classified as definite or probable. Exposure was significantly more frequent in men than in women (68% v 18%, P < .001).
  • Among patients with asbestos exposure, the latency period from first exposure to onset of symptoms ranged from 19 to 45 years (median 32 years).
  • Median survival from diagnosis for all patients with pleural mesothelioma was 9 months. The median delay from first symptom to diagnosis was 3.5 months.
  • In the multivariate analysis of 118 patients with complete data on all 11 features, stage remained highly significant (P < .0001). High platelet count (P = .001) and asbestos exposure (P = .02) had a negative association with survival.
  • Thrombocytosis (a platelet count of 400,000 per microliter or more) occurred in 110 patients (41%) at the time of diagnosis.
  • Pleural fluid cytology was done in 152 patients. It found malignant cells in 54 (35%) and gave a mesothelioma diagnosis in only four. Thoracoscopy had a diagnostic rate of 81% and open pleural biopsy 93%.
  • Survival did not differ significantly between no surgery (median 8 months), palliative surgery (9.8 months) and extrapleural pneumonectomy (9.3 months) (P > .23).
  • Patients who received chemotherapy had longer median survival than those who did not (12.3 vs 7.3 months, P < .02). There were no responses to regimens without doxorubicin in 38 patients, and a 12.5% objective response rate in 64 patients given doxorubicin-containing regimens.
• The authors' conclusion: The authors concluded that there was no cure of DMM and no drastic survival differences between treatment groups. They found radical surgery and radiotherapy ineffective and response to chemotherapy low. They said the series can serve as a baseline for future studies and for choosing stratification variables in future trials.
• Limitations the authors state:
  • Treatment groups were not necessarily comparable at diagnosis, so survival differences compare patient groups, not treatment efficacy.
  • The multivariate analysis used only the 118 patients with complete data. Charts with missing values tended to be about 3 years older, which is a potential source of bias.
  • The authors state that the recorded asbestos exposure rate underestimates the true exposure rate.
  • The chemotherapy survival difference may not be due to the chemotherapy itself, because it occurred despite little response to the drugs.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleura, Asbestos Exposure, Thoracotomy, Pleural Biopsy, Cytology, Median Overall Survival, Multivariate Analysis.

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