Malignant pleural mesothelioma incidence and survival in the Republic of Ireland 1994-2009

Our plain-English summary of Malignant pleural mesothelioma incidence and survival in the Republic of Ireland 1994-2009, by C.J. Jennings, P.M. Walsh, S. Deady, et al (Cancer Epidemiology, 2014).

The study

• Authors: C.J. Jennings, P.M. Walsh, S. Deady, B.J. Harvey, W. Thomas
• Journal: Cancer Epidemiology
• Published: 2014;38(1):35-41
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: Malignant pleural mesothelioma (MPM) is a rare malignancy associated with exposure to asbestos. The protracted latent period of MPM means that its incidence has continued to rise across Europe after the introduction of restrictions on asbestos use. In order to obtain a clearer indication of trends in the Republic of Ireland (ROI), incidence and survival were assessed based on all MPM cases reported since the establishment of the National Cancer Registry of Ireland (NCR).

Methods: NCR recorded 337 MPM diagnoses in the ROI during 1994-2009. Survival was assessed for all cases diagnosed with adequate follow-up (n=330). Crude and European age-standardized incidence rates were calculated for all cases and for 4-year periods. A Cox model of observed (all-cause) survival was used to generate hazard ratios for the effect of: gender; age at diagnosis; diagnosis cohort; region of residence; histological type; and tumour stage. Single P-values for the variables indicated were calculated using either a stratified log-rank test or stratified trend test.

Results: Over the study period the age-standardized MPM incidence in the ROI rose from 4.98cases per million (cpm) to 7.24cpm. The 1-year survival rate for all MPM cases was 29.6% (CI 24.7-34.6%). Excess mortality risk was associated with age at diagnosis (75-89 yrs vs. 55-64 yrs, HR 1.88, 95% CI 1.35-2.63, P<0.001) and tumour stage (III vs. I HR 1.57, 95% CI 1.00-2.48, P<0.05; IV vs. I HR 1.55, 95% CI 1.08-2.21, P<0.05). Age showed a significant survival trend (P<0.001) but tumour stage did not (P=0.150). There was significant heterogeneity between the survival of patients resident in different regions (P=0.027).

Conclusion: MPM incidence and mortality continued to rise in the ROI after the restrictions on asbestos use and the predictors of survival detected in this study are broadly consistent with those identified for other countries.

Copyright © 2013 Elsevier Ltd. All rights reserved.

In plain English

Using Ireland's National Cancer Registry, the authors studied all malignant pleural mesothelioma (cancer of the lung lining) cases diagnosed in the Republic of Ireland, 1994–2009. Of 337 cases, 330 could be followed for survival. The age-standardized rate rose from 4.98 cases per million per year in 1994–1997 to 7.24 in 2006–2009. Among men it rose from 9.08 to 13.11 per million. Estimated one-year survival was 29.6% (95% confidence interval 24.7–34.6%). Patients aged 75–89 survived less well than those aged 55–64 (hazard ratio 1.88, confidence interval 1.35–2.63). Patients with stage III and IV tumours had poorer survival than those with stage I. Women survived significantly longer in one statistical model, but the difference was not statistically significant in the authors' main model. Survival differed between health regions. The study did not report individual asbestos exposure. Final occupation was known for 223 of 362 patients diagnosed 1994–2010, most often construction (28) and woodworking (22). Tumour type and stage were often missing; the authors noted better diagnosis may explain part of the rise. The authors concluded that diagnoses kept rising, consistent with other industrialised countries.

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: Population-based cancer registry study of incidence and survival (retrospective analysis of national registry data)
• Who was studied: All 337 malignant pleural mesothelioma cases recorded in the Republic of Ireland, 1994–2009. 330 had follow-up for survival analysis (289 male, 41 female). Follow-up ran to the end of 2010.
• Exposure: Asbestos exposure was not measured for individual patients. Only final occupation was available, known for 223 of 362 patients diagnosed 1994–2010.
• Main results:
  • The age-standardized annual incidence of pleural mesothelioma (all patients) rose from 4.98 cases per million in 1994–1997 to 7.24 cases per million in 2006–2009.
  • Among males, the age-standardized incidence of pleural mesothelioma rose from 9.08 to 13.11 cases per million between 1994–1997 and 2006–2009.
  • The estimated one-year observed (all-cause) survival rate for the 330 patients in the survival analysis was 29.6% (95% CI 24.7–34.6%).
  • Patients aged 75–89 at diagnosis had poorer survival than those aged 55–64: hazard ratio 1.88 (95% CI 1.35–2.63, p less than 0.001).
  • Among patients with known stage (153), those with stage III and stage IV tumours had poorer survival than those with stage I. Stage III: hazard ratio 1.58 (95% CI 1.00–2.48). Stage IV: hazard ratio 1.67 (95% CI 1.09–2.55). Both p less than 0.05.
  • Female patients had significantly better survival than males in an adjusted but unstratified model (hazard ratio 0.68, 95% CI 0.47–0.98, p = 0.036). In the fully stratified main model the difference was not statistically significant.
  • Survival differed significantly between the four health service regions of residence (p = 0.027).
  • 140 patients (44%) received no radiotherapy, chemotherapy or surgery. Their median survival was 2.8 months, compared with 9.0 months for patients who received some treatment.
  • The share of diagnoses in patients aged 75 or over rose from 17% (10 cases) in 1994–1997 to 28% (33 cases) in 2006–2009.
  • Among patients with known final occupation, the most represented groups were construction (28 cases) and woodworking (22 cases).
• The authors' conclusion: The authors concluded that the number of malignant pleural mesothelioma diagnoses in the Republic of Ireland continued to rise over 1994–2009, consistent with other industrialised countries. They also concluded that the survival predictors found were comparable with other studies.
• Limitations the authors state:
  • Histological subtype was known for only 81 of the 330 patients in the survival analysis.
  • Tumour stage was known for only 153 patients, so no further conclusion could be drawn about histological type or stage.
  • Cause-specific survival could not be assessed because causes of death were often unknown.
  • Part of the rise in mesothelioma incidence may reflect improved diagnostic specificity.
  • Lead-time bias may have contributed to survival differences between subgroups.
  • Better survival among treated patients probably also reflects other favourable characteristics of those patients.
  • Occupational data were incomplete, and the authors advised caution in drawing conclusions from them.

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, Cancer Registry, Incidence, Hazard Ratio, P-Value.

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