Stomach Cancer and Exposure to Talc Powder without Asbestos via Chinese Herbal Medicine: A Population-Based Cohort Study

Our plain-English summary of Stomach Cancer and Exposure to Talc Powder without Asbestos via Chinese Herbal Medicine: A Population-Based Cohort Study, by C.J. Chang, Y.H. Yang, P.C. Chen, et al (International Journal of Environmental Research and Public Health, 2019).

The study

• Authors: C.J. Chang, Y.H. Yang, P.C. Chen, H.Y. Peng, Y.C. Lu, S.R. Song, H.Y. Yang
• Journal: International Journal of Environmental Research and Public Health
• Published: 2019;16(5)
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The present investigation was designed to explore the risk of stomach cancer by oral intake of talc powder without asbestos. We conducted a population-based cohort study on a randomly sampled cohort from Taiwan's health insurance database, with population of 1,000,000. The study participants were followed up through 2013. The outcome event of interest was the diagnosis of stomach cancer. The exposure of interest was the prescription of talc powder. Cox regression analyses were performed respectively. There were 584,077 persons without talc exposure and 21,575 talc users, 1849 diagnosed with stomach cancer. Persons with exposure of talc had a higher hazard ratio of stomach cancer (adjusted hazard ratio, 2.13; 95% confidence interval (CI), 1.54⁻2.94; p < 0.001). Classification by cumulative exposure of talc yielded adjusted hazard ratios of stomach cancer of 1.58 (95% CI, 0.79⁻3.17; p = 0.19) and 2.30 (95% CI, 1.48⁻3.57; p < 0.001) among persons with high (>21 g) and medium (6⁻21 g) exposure of talc, as compared to the low-exposure counterparts. Our data demonstrated positive association between increased risk of stomach cancer and oral intake of talc without asbestos. Despite the absence of dose-response effect, there might be a link between stomach cancer and talc.

In plain English

Using Taiwan's health insurance records, the authors followed 605,652 adults from 1997 to 2013 to see whether oral talc in Chinese herbal medicine was linked to stomach cancer. Of these, 21,575 received talc and 1849 developed stomach cancer. Adjusted for age, gender and other illnesses, talc-exposed periods had a hazard ratio of 2.13 (95% confidence interval 1.54 to 2.94) compared with unexposed periods. Compared with a low-to-none group (6 g or less, which included some low-dose users), medium cumulative doses (6 to 21 g) had a hazard ratio of 2.30 (1.48 to 3.57). Compared with the same group, doses over 21 g had 1.58 (0.79 to 3.17), which was not statistically significant. When observations with under five years to stomach cancer, drop-out or end of follow-up were excluded, neither dose group showed a statistically significant increase. The authors concluded that oral talc without asbestos was positively associated with stomach cancer. They said the lack of a dose-response pattern made causation less likely. They could not adjust for smoking, diet or body weight. A 2018 microscope analysis found no asbestos, but the authors knew of no information on asbestos in medical talc for 1997 to 2005.

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 cohort study using Taiwan's National Health Insurance Research Database. Talc exposure was treated as time-dependent and analysed by Cox proportional hazards regression.
• Who was studied: 605,652 adults (aged 20 or older in 1997, with no prior cancer) from a random sample of 1,000,000 Taiwan health insurance beneficiaries. They were followed from 1 January 1997 to 31 December 2013, an average of 16.4 years. 584,077 had no talc exposure and 21,575 were talc users.
• Exposure: Oral intake of talc powder (described as without asbestos) prescribed in extracted Chinese herbal products. Cumulative dose was grouped as low-to-none (6 g or less), medium (6 to 21 g) and high (more than 21 g).
• Main results:
  • Compared with unexposed periods, talc-exposed periods had an adjusted hazard ratio for stomach cancer of 2.13 (95% CI 1.54 to 2.94). This was based on 45 cases in 180,467 person-years exposed versus 1804 cases in 9,728,639 person-years unexposed.
  • Stomach cancer incidence was 2.49 per 10,000 person-years in the talc-exposed period and 1.85 per 10,000 person-years in the unexposed period.
  • Medium cumulative talc exposure (6 to 21 g) had an adjusted hazard ratio of 2.30 (95% CI 1.48 to 3.57; p less than 0.001), based on 23 cases. The comparison group was low-to-none exposure (6 g or less).
  • High cumulative talc exposure (more than 21 g) had an adjusted hazard ratio of 1.58 (95% CI 0.79 to 3.17; p = 0.19), based on 10 cases. The comparison group was low-to-none exposure (6 g or less). This result was not statistically significant.
  • In a sensitivity analysis that split exposure at the median (10.5 g), people with 10.5 g or less had an adjusted hazard ratio of 2.40 (95% CI 1.54 to 3.73) compared with unexposed people.
  • In the same median-split analysis, people with more than 10.5 g had an adjusted hazard ratio of 1.89 (95% CI 1.19 to 3.01) compared with unexposed people.
  • The authors excluded observations with less than five years to stomach cancer, drop-out or end of follow-up. In that analysis, compared with low-to-none exposure, the hazard ratios were 0.86 (95% CI 0.39 to 1.93) for medium exposure and 1.99 (95% CI 0.81 to 3.59) for high exposure. Neither was statistically significant.
  • Among talc-exposed patients, the mean duration of talc exposure was 23.8 days.
  • A scanning electron microscopy analysis of 100 talc particles, done on 30 March 2018, detected no asbestos or asbestiform fibers.
• The authors' conclusion: The authors concluded that there is a positive association between increased risk of stomach cancer and oral intake of talc without asbestos, although a linear dose-response relationship was not shown.
• Limitations the authors state:
  • Smoking, body-mass index and dietary factors could not be obtained from the insurance database.
  • Because comorbidities were identified from billing codes, their prevalence may have been overestimated.
  • Other geographic environmental carcinogens, and some risk factors such as pernicious anemia, could not be adjusted for.
  • Talc taken as traditional herbal decoction was not captured, so real talc exposure might be underestimated.
  • The talc-exposed population was small, so the confidence interval of the hazard ratio was relatively wide.
  • The authors stated that the lack of a dose-response relationship made a causal effect of talc on stomach cancer less likely.
  • The authors linked the non-significant results after the five-year exclusion to the small number of cases left.
  • There was no information on whether medical talcum powder contained asbestos during 1997 to 2005.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Stomach cancer, Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Stomach Cancer, Talc, Cohort Study, Hazard Ratio, confidence interval, Cumulative Exposure, Dose-response relationship.

Related studies

• Talc exposure and risk of stomach cancer: Systematic review and meta-analysis of occupational cohort studies — C.J. Chang, Y.K. Tu, et al. (2020)
• Exposure to nitrosamines, carbon black, asbestos, and talc and mortality from stomach, lung, and laryngeal cancer in a cohort of rubber workers — K. Straif, U. Keil, et al. (2000)
• Talc-treated rice and Japanese stomach cancer — R.R. Merliss (1971)
• Talc-coated rice as a risk factor for stomach cancer — G.N. Stemmermann, L.N. Kolonel (1978)
• Exposure to chrysotile mining dust and digestive cancer mortality in a Chinese miner/miller cohort — S. Lin, X. Wang, et al. (2014)
• Occupational Exposure to Talc Increases the Risk of Lung Cancer: A Meta-Analysis of Occupational Cohort Studies — C.J. Chang, Y.K. Tu, et al. (2017)

Browse more research in International Journal of Environmental Research and Public Health, or return to medical research.