The incidence of malignancies in asbestosis with chrysotile exposure: a large Chinese prospective cohort study

Our plain-English summary of The incidence of malignancies in asbestosis with chrysotile exposure: a large Chinese prospective cohort study, by J. Wang, X. Huang, R. Ma, et al (Frontiers in Oncology, 2023).

The study

• Authors: J. Wang, X. Huang, R. Ma, Q. Zhang, N. Wu, X. Du, Q. Ye
• Journal: Frontiers in Oncology
• Published: 2023;13:1172496
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Asbestos exposure is closely related to the occurrence and development of various malignancies. This prospective cohort study aimed to evaluate the incidence rate and potential risk factors in a cohort of asbestosis patients in China.

Methods: The incidence of malignancies was determined in patients who had been exposed to chrysotile asbestos and diagnosed with asbestosis sequentially at Beijing Chaoyang Hospital from 1 January 2007 to 31 December 2019. Cox regression analyses were used to analyze the correlations between clinical variables and asbestosis combined with malignancies.

Results: A total of 618 patients with asbestosis were identified, of whom 544 were eligible for analysis. Among them, 89 (16.36%) were diagnosed with various malignancies. The standardized incidence ratios (SIRs) of patients with asbestosis combined with malignancies were 16.61, 175, 5.23, and 8.77 for lung cancer, mesothelioma, breast cancer, and endometrial carcinoma, respectively. The risks of all malignancies and lung cancer increased with initial exposure before 17 years old, longer asbestos exposure, and smoking.

Conclusions: The SIRs of patients with asbestosis-related malignancies were significantly increased in lung cancer, mesothelioma, breast cancer, and endometrial carcinoma in a hospital-based Chinese cohort. Smoking and the duration of asbestos exposure increased the risk of lung cancer.

Copyright © 2023 Wang, Huang, Ma, Zhang, Wu, Du and Ye.

In plain English

This hospital-based prospective cohort study followed 544 patients with chrysotile exposure and asbestosis, diagnosed at Beijing Chaoyang Hospital, China, in 2007 to 2019, until the end of 2021. Most (55.1%) were textile workers, and exposure was measured only as years of employment. Over a median follow-up of 10 years, 89 (16.36%) had cancer, most often lung cancer (52). Of these, 27 were diagnosed at the same time as asbestosis and 62 later. Compared with expected Chinese rates, standardized incidence ratios were 5.36 (95% CI 5.09 to 5.66) for all cancers, 16.61 (14.82 to 18.68) for lung cancer and 175 (68.05 to 644.07) for mesothelioma. Among women they were 5.23 (4.39 to 6.26) for breast cancer and 8.77 (6.66 to 11.75) for endometrial carcinoma. Smoking and first exposure before age 17 were linked to higher risk of all cancers and of lung cancer. The authors said longer exposure raised risk, yet their tables give the higher hazard to 1 to 12 years versus 12 to 44 years. The authors noted screening bias, a single center, no control group of dust-exposed workers without asbestosis, and no fiber concentration data.

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: Hospital-based prospective cohort study (described by the authors as descriptive), with standardized incidence ratios against Chinese national cancer rates and Cox regression
• Who was studied: 544 of 618 patients aged 18 or older with chrysotile exposure and asbestosis diagnosed at Beijing Chaoyang Hospital, Beijing, China, from 1 January 2007 to 31 December 2019, followed to 31 December 2021; mean age at entry 69.73 years; 240 (44.1%) male, 304 female
• Exposure: Occupational chrysotile asbestos exposure, measured only as duration of employment in years (median 12 years, range 1 to 44). Jobs included 300 (55.1%) textile workers, 19 maintenance workers, 26 batchers, 12 brake pad producers, 20 building material producers, 19 boiler workers and 148 other workers
• Main results:
  • 89 of 544 patients with asbestosis (16.36%) were diagnosed with malignancies over a median follow-up of 10.0 years
  • Of the 89 patients with malignancies, 27 (30.34%) were diagnosed with asbestosis and cancer at the same time, and 62 (69.66%) were diagnosed with asbestosis first and with cancer a median of 3.0 years later
  • All malignancies combined: SIR 5.36 (95% CI 5.09 to 5.66), with 89 observed against 16.59 expected
  • Lung cancer: 52 patients (9.56%), SIR 16.61 (95% CI 14.82 to 18.68); 33 of the 52 had adenocarcinoma
  • Mesothelioma: 7 patients (1.29%), SIR 175 (95% CI 68.05 to 644.07); the site of the mesothelioma was not specified
  • Among female patients (n = 304): breast cancer in 8, SIR 5.23 (95% CI 4.39 to 6.26); endometrial carcinoma in 5, SIR 8.77 (95% CI 6.66 to 11.75)
  • All malignancies, Cox regression: first exposure before 17 years old HR 2.27 (95% CI 1.31 to 3.93); smoking HR 1.66 (95% CI 1.00 to 2.67)
  • Lung cancer, Cox regression: smoking HR 2.49 (95% CI 1.38 to 4.50); first exposure before 17 years old HR 2.20 (95% CI 1.07 to 4.50)
  • Lung cancer and exposure duration: HR 10.83 (95% CI 4.64 to 25.27). The text describes this as 'year of asbestos exposure', but Table 4 assigns this HR to 1 to 12 years of exposure, with 12 to 44 years as the reference group
  • Mesothelioma: risk reported as increasing with years of asbestos exposure, HR 7.38 (95% CI 1.24 to 43.97)
  • No significant association was found between asbestosis stage and occurrence of malignancy, and no significant difference in malignancy incidence between work types
  • No significant difference was found between gynecologic, breast or gastrointestinal cancer and asbestos exposure time
• The authors' conclusion: The authors concluded that, in this cohort, incidence of lung cancer, mesothelioma, breast cancer and endometrial carcinoma was greatly increased among patients with asbestosis, and that duration of asbestos exposure and smoking history were related to lung cancer
• Limitations the authors state:
  • No data on workplace environments or asbestos fiber concentrations, so an exposure-response relationship could not be estimated
  • Possible selection bias: all patients came from a single center known for occupational medicine
  • No control group of dust-exposed workers without asbestosis
  • Screening bias may have led to early diagnosis or overdiagnosis. The authors noted increased SIRs for unrelated cancers and said raised SIRs for gynecologic, breast and gastrointestinal cancers may partly reflect screening
  • Numbers were too small to examine cancer types with only one or two expected cases

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Cohort Study, Asbestos Exposure, Incidence, Standardized Incidence Ratio (SIR), Lung Cancer, Mesothelioma, Carcinoma.

Related studies

• Exposure-response estimate for lung cancer and asbestosis in a predominantly chrysotile-exposed Chinese factory cohort — M.N. Courtice, X. Wang, et al. (2016)
• Cause-specific mortality in a Chinese chrysotile textile worker cohort — X. Wang, S. Lin, et al. (2013)
• Exposure to chrysotile mining dust and digestive cancer mortality in a Chinese miner/miller cohort — S. Lin, X. Wang, et al. (2014)
• Mortality in a Chinese chrysotile miner cohort — X. Wang, S. Lin, et al. (2012)
• Cause-specific mortality in relation to chrysotile-asbestos exposure in a Chinese cohort — S. Lin, X. Wang, et al. (2012)
• Occupational class, occupational mobility and cancer incidence among middle-aged men and women: a prospective study of the French GAZEL cohort* — M. Melchior, M. Goldberg, et al. (2005)

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