Mesothelioma continues to increase even 40 years after exposure – Evidence from long-term epidemiological observation

Global, Regional, and National Burden of Mesothelioma 1990-2019: A Systematic Analysis of the Global Burden of Disease Study 2019

Rationale: Mesothelioma has become a major health burden since World War II because of the use of asbestos. Although many countries have imposed bans on asbestos, there remain significant mortality and morbidity from mesothelioma because of its long latent period and aggressiveness. Also, the use of asbestos is increasing in low-income countries, potentiating risk of mesothelioma in the coming decades. Assessment of the global burden of mesothelioma is required to take proper measures against the disease. Objectives: To assess the burden of mesothelioma from 1990 to 2019 at the global, regional, and national levels and to investigate patterns according to sex, age, sociodemographic index, and risk factors. Methods: The numbers, rates, and age-standardized rates of incidence, death, and disability-adjusted life years (DALYs) of mesothelioma in 204 countries and territories from 1990 to 2019 were estimated using vital registration and cancer registry data. The relationship between sociodemographic index and age-standardized DALY rate was determined, and DALYs attributable to occupational exposure to asbestos were calculated. Results: In 2019, there were 34,511 (95% uncertainty interval [UI], 31,199 to 37,771) incident cases of mesothelioma globally, with an age-standardized rate of 0.43 per 100,000 persons (95% UI, 0.38 to 0.47), which decreased between 1990 and 2019 by -12.6% (95% UI, -21.8% to -2.3%). Mesothelioma was responsible for 29,251 (95% UI, 26,668 to 31,006) deaths in 2019, with an age-standardized rate of 0.36 deaths per 100,000 persons (95% UI, 0.33 to 0.39), which decreased between 1990 and 2019 by -9.6% (95% UI, -17.8% to -1.1%). The age-standardized incidence rate increased in central Europe between 1990 and 2019 by 46.1% (95% UI, 16.6% to 72.4%). The Netherlands, Australia, and the United Kingdom had the highest age-standardized incidence rates. Incidence rates were higher in men than in women ages 45-49 to 90-94 years, peaking at 85-89 years. Occupational exposure to asbestos contributed to 85.2% (95% UI, 82.1% to 88.1%) of DALYs. Conclusions: The global burden of mesothelioma is decreasing in terms of age-standardized incidence and mortality rates. Mesothelioma remains a substantial public health challenge in many parts of the world.

Current causes of mesothelioma: how has the asbestos ban changed the perspective?

The association of mesothelioma, a lethal lung disease, with asbestos has led to an absolute ban on asbestos in at least 55 countries worldwide. The purpose of this paper is to review residual exposure to asbestos as well as other emerging causes of mesothelioma outside asbestos. The review provides detailed description of asbestos minerals, their geographical locations, mesothelioma in these areas, as well as contemporary possible sources of asbestos exposure. Second, we examine other emerging causes of mesothelioma including: ionizing radiation as the second most important risk factor after asbestos, particularly relevant to patients undergoing radiotherapy, third, carbon nanotubes which are under investigation and fourth, Simian virus 40. In the case of asbestos per se, the greatest risk is from occupational exposure during mining and subsequent processing. Of the non-occupational exposures, environmental exposure is most serious, followed by exposure from indoor asbestos minerals and secondary familial exposure. Overall, asbestos is still a major risk factor, but alternative causes should not be neglected, especially in young people, in women and those with a history of radiotherapy or living in high-risk locations.

Mortality for Mesothelioma and Lung Cancer in a Cohort of Asbestos Cement Workers in BARI (Italy): Time Related Aspects of Exposure

OBJECTIVE

In this cohort mortality study we used an exposure index to evaluate individual cumulative exposure as proxy of asbestos dose and we evaluated change in cancer mortality pattern after long time since the end of exposure.

METHODS

We calculated standardized mortality ratios (SMRs) for several causes of death stratified by latency, cumulative exposure, and time since last exposure (TSLE).

RESULTS

Latency: we observed a peak and then a decrease in SMR for lung, pleural, and peritoneal cancer. Cumulative Exposure: We observed a peak and then a decrease in SMR for lung and pleural cancer, not for peritoneal cancer. TSLE: Pleural cancer SMR peaked at 20 to 29 years, then decreased, peritoneal cancer SMR reached a plateau after 20 years and lung cancer mortality was in excess in each class.

CONCLUSIONS

We found different patterns in mortality in the main asbestos-related tumors.

Geographic study of mortality due to mesothelioma in Peru and its evolution

BACKGROUND

Peru has a public health problem because of asbestos imports. We analyzed the mortality trends for mesothelioma in Peru and its provinces from 2005 to 2014 and estimated their relationship with the amount of asbestos imported previously.

METHODS

We computed age-standardized mortality rates (ASMRs) per 100,000 population (direct method and SEGI world standard population reference), and the standardized mortality ratio (SMR). The relationship between the amount of asbestos imported annually along the period 1965-2010 and the number of mesothelioma deaths per year from 2005 to 2014 was estimated by log-linear Poisson regression models and Pearson correlation calculations.

RESULTS

After correcting the number of deaths, Peru registered 428 cases (or 430 when corrected cases are rounded by sex) between 2005 and 2014. The highest ASMRs were in Arequipa and Callao (range: 0.40-0.41/100,000 population), followed by Huancavelica (0.36/100,000 population). This translates into approximately one death per each 68-111 of asbestos tons imported. The latency period for the higher level of positive correlation found was 8 years (r = 0.8). Male female sex ratio was lower in provinces such as Junin and Hunacavelica with geological asbestos risk.

CONCLUSIONS

Two patterns of mesothelioma risk have been detected, occupational and environmental. During the 2002-2006 years, Peru increased the asbestos use. If crocidolite imports were also increased, this could be behind the 8 years latency period detected. Peru should boost strategies towards the total ban of all forms of asbestos.

Comment on Małgorzata Krówczyńska and Ewa Wilk. Environmental and Occupational Exposure to Asbestos as a Result of Consumption and Use in Poland. Int. J. Environ. Res. Public Health 2019, 16, 2611

Krówczyńska M [...].

Cumulative asbestos exposure and mortality from asbestos related diseases in a pooled analysis of 21 asbestos cement cohorts in Italy

BACKGROUND

Despite the available information on cancer risk, asbestos is used in large areas in the world, mostly in the production of asbestos cement. Moreover, questions are raised regarding the shape of the dose response relation, the relation with time since exposure and the association with neoplasms in various organs. We conducted a study on the relationship between cumulative asbestos exposure and mortality from asbestos related diseases in a large Italian pool of 21 cohorts of asbestos-cement workers with protracted exposure to both chrysotile and amphibole asbestos.

METHODS

The cohort included 13,076 workers, 81.9% men and 18.1% women, working in 21 Italian asbestos-cement factories, with over 40 years of observation. Exposure was estimated by plant and period, and weighted for the type of asbestos used. Data were analysed with consideration of cause of death, cumulative exposure and time since first exposure (TSFE), and by gender. SMRs were computed using reference rates by region, gender and calendar time. Poisson regression models including cubic splines were used to analyse the effect of cumulative exposure to asbestos and TSFE on mortality for asbestos-related diseases. 95% Confidence Intervals (CI) were computed according to the Poisson distribution.

RESULTS

Mortality was significantly increased for 'All Causes' and 'All Malignant Neoplasm (MN)', in both genders. Considering asbestos related diseases (ARDs), statistically significant excesses were observed for MN of peritoneum (SMR: men 14.19; women 15.14), pleura (SMR: 22.35 and 48.10), lung (SMR: 1.67 and 1.67), ovary (in the highest exposure class SMR 2.45), and asbestosis (SMR: 507 and 1023). Mortality for ARDs, in particular pleural and peritoneal malignancies, lung cancer, ovarian cancer and asbestosis increased monotonically with cumulative exposure. Pleural MN mortality increased progressively in the first 40 years of TSFE, then reached a plateau, while peritoneal MN showed a continuous increase. The trend of lung cancer SMRs also showed a flattening after 40 years of TSFE. Attributable proportions for pleural, peritoneal, and lung MN were respectively 96, 93 and 40%.

CONCLUSIONS

Mortality for ARDs was associated with cumulative exposure to asbestos. Risk of death from pleural MN did not increase indefinitely with TSFE but eventually reached a plateau, consistently with reports from other recent studies.

Change in prevalence of asbestos-related disease among sheet metal workers 1986 to 2016

BACKGROUND

A medical screening program began in 1986 for sheet metal workers exposed to asbestos, primarily while working alongside insulators applying spray-on asbestos materials, a practice banned in 1973. Exposure continues during maintenance, renovation, and repair.

METHODS

Radiographic abnormalities among 26 397 sheet metal workers examined from 1986 to 2016 were analyzed by year of entry into the trade. Logistic regression was used to examine risk factors for parenchymal and pleural abnormalities among the overall study population and among the subcohort who entered the trade after 1973.

RESULTS

Prevalence of parenchymal disease was 17.4% for those starting work before 1950 compared with 0.8% for those starting work after 1973 (adjusted prevalence odds ratio [pOR] = 26.65, 95% confidence interval [CI] = 18.46-38.46). For each calendar year after 1973, entering the trade 1 year later was associated with an estimated 12.7% decreased odds of acquiring asbestos-related disease (adjusted pOR = 0.873, 95% CI = 0.832-0.916).

CONCLUSION

Sheet metal workers who began work after the US implemented environmental and occupational regulations develop asbestos-related disease at much reduced rates, consistent with regulatory projections made for nonmalignant asbestos-related disease by the Occupational Safety and Health Administration at the time. Cancer remains a concern among this cohort, and lung cancer screening recommendations should consider year of entry into the trade. This study highlights the importance of regulatory intervention and of continued surveillance.

Risk of mesothelioma after cessation of asbestos exposure: a systematic review and meta-regression

PURPOSE

A 'risk reversal' has been observed for several human carcinogens following cessation of exposure, but it is unclear whether it also exists for asbestos-related mesothelioma.

METHODS

We conducted a systematic review of the literature and identified nine studies that reported information on risk of mesothelioma after cessation of asbestos exposure, and performed a meta-regression based on random effects models. As comparison we analyzed results on lung cancer risk from four of these studies.

RESULTS

A total of six risk estimates from five studies were included in the meta-analysis. The summary relative risk (RR) of mesothelioma for 10-year interval since cessation of exposure was 1.02 [95% confidence interval (CI) 0.87-1.19; p-heterogeneity 0.01]. The corresponding RR of lung cancer was 0.91 (95% CI 0.84-0.98).

CONCLUSIONS

This analysis provides evidence that the risk of mesothelioma does not decrease after cessation of asbestos exposure, while lung cancer risk does.

Polymeric films loaded with cisplatin for malignant pleural mesothelioma: a pharmacokinetic study in an ovine model

BACKGROUND

Malignant pleural mesothelioma (MPM) continues to be a distressing tumor due to its aggressive biologic behavior and scanty prognosis. Several therapeutic approaches have been tested both in clinical and preclinical settings, being intrapleural chemotherapy one of the most promising. Some years ago, our interest focused on polymeric films loaded with cisplatin for the adjuvant intrapleural treatment of surgical patients. After in vitro and in vivo studies in a rat recurrence model of MPM, the aim of this study was to evaluate the pharmacokinetics of the polymeric films in a sheep model in view of further studies in a clinical setting.

METHODS

An ovine model was used. Animals were divided into four groups according to pharmacologic treatment: control group (three animals undergoing left pneumonectomy and saline-NaCl solution); intrapleural hyaluronate cisplatin films (HYALCIS) group (six animals undergoing left pneumonectomy and intrapleural application of polymeric films loaded with cisplatin); intrapleural cisplatin solution (six animals undergoing left pneumonectomy and intrapleural application of cisplatin solution); intravenous cisplatin (five animals undergoing left pneumonectomy and intravenous administration of cisplatin solution). The primary objective was the plasmatic and pleural concentration of cisplatin in the treatment groups. The secondary objective was the treatment-related toxicity evaluated by plasmatic analysis performed at prearranged time intervals and histological examinations of tissue samples collected during animal autopsy. Analysis of variance (ANOVA) was used for statistical analysis. Bonferroni correction was applied for comparison between all groups.

RESULTS

Twenty female Sardinian sheep with a mean weight of 45.1 kg were studied. All animals survived the surgical procedures. The whole surgical procedure had a mean duration of 113 minutes. Cisplatin blood levels obtained from polymeric films application were low during the first 24 hours after the application; then, the cisplatin blood level increased gradually and progressively until it reached significantly higher plasmatic concentrations after 120 hours compared to intrapleural cisplatin solution (P=0.004) and intravenous administration (P=0.001), respectively. Considering cisplatin concentration at 168 hours after the application, animals treated with polymeric films had higher plasmatic values than animals treated with intrapleural cisplatin solution and intravenous cisplatin (P=0.001). Despite the high cisplatin plasmatic concentrations, treatment related-toxicity towards kidneys and liver was comparatively lower compared to the intravenous and intrapleural cisplatin administration and closer to the control levels.

CONCLUSIONS

Polymeric films loaded with cisplatin allowed to reach significantly higher intrapleural and plasmatic cisplatin concentrations compared to intrapleural and intravenous cisplatin solution, providing at the same time, a significant reduction of treatment related toxicity.