Occupational risk factors for renal cell cancer: a case--control study in northern Italy

Our plain-English summary of Occupational risk factors for renal cell cancer: a case--control study in northern Italy, by S. Mattioli, D. Truffelli, A. Baldasseroni, et al (Journal of Occupational and Environmental Medicine, 2002).

The study

• Authors: S. Mattioli, D. Truffelli, A. Baldasseroni, A. Risi, B. Marchesini, C. Giacomini, P. Bacchini, F.S. Violante, E. Buiatti
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2002;44(11):1028-36
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Relatively little is known about occupational and other risk factors for renal-cell carcinoma (RCC). Associations between RCC and occupations, exposures and other factors were investigated in a hospital-based case-control study in Bologna (central-northern Italy). Between 1986 and 1994, 324 histologically confirmed RCC cases were diagnosed at Policlinico S. Orsola-Malpighi in patients from the Province of Bologna. Corresponding control subjects admitted to the same hospital with any diagnosis except RCC were matched for sex, age, and residency. We studied the 249 cases and 238 controls for whom detailed information on occupational history, diet, smoking habits, alcohol and drug intake was obtained. At conditional logistic regression, among males (167 matched pairs), significant matched odds ratios (OR) were found, after adjusting for cigarette smoking and alcohol intake, for high body-mass index BMI (third quartile: OR, 4.91; confidence interval [95% CI], 1.56-15.5; last quartile: OR, 4.42; 95% CI, 1.48-13.18), railway workers (OR, 10.14; 95% CI, 1.46-70.17) and asbestos exposure (OR, 7.11; 95% CI, 1.46-34.51); nearly significant OR were found for managers (OR, 3.59; 95% CI, 0.82-15.59) and metal workers (OR, 2.21; 95% CI, 0.99-5.37). Among females (52 pairs), significant OR were found for BMI > 25.4 (OR, 8.46; 95% CI, 1.02-68.0). Railway workers (on or near to trains) may have increased risk of developing RCC, possibly due to asbestos exposure. Studies are required on possible risks encountered by railway (and metal) workers and by managers.

In plain English

This hospital-based case-control study in Bologna, Italy, looked for occupational risk factors for renal cell carcinoma (RCC), a kidney cancer. Each of 324 patients with confirmed RCC registered at one Bologna hospital from 1987 to 1994 was matched to a patient admitted there in 1991 for another condition. Responses, by mail or telephone, came from 249 cases and 238 controls, forming 219 pairs where both members responded. Among men, asbestos exposure judged certain or very probable was linked to higher odds of RCC (odds ratio 7.11, 95% CI 1.46 to 34.51; 11 exposed cases, 4 exposed controls). The study did not report participants' asbestos fiber types. Among men, work on or near trains was also linked to higher odds (odds ratio 10.14, 95% CI 1.46 to 70.17), rising with years employed. Because of missing data, both estimates used 150 male pairs. High body-mass index was linked to RCC in men and women. The authors concluded that railway workers may have increased RCC risk, possibly from asbestos exposure. They cautioned that hospital controls and many comparisons could have affected results.

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 case-control study with 1:1 matched controls, analysed by conditional logistic regression
• Who was studied: 324 patients with histologically confirmed renal cell carcinoma living in Bologna and its Province, registered at Policlinico Sant'Orsola-Malpighi from January 1987 to December 1994. Each was matched 1:1 to one of 324 patients admitted to the same hospital in 1991 with any diagnosis except RCC. Responses were collected by mailed questionnaire or by telephone interview. 487 people responded (249 cases, 238 controls), giving 219 matched pairs in which both members responded (167 male pairs, 52 female pairs).
• Exposure: Lifetime job histories and occupational exposures, reported by questionnaire. An industrial hygienist coded exposures judged 'certain/very probable': asbestos, petroleum products, solvents, mineral oils, welding fumes, foundry fumes, inorganic lead and pesticides. The study did not report which asbestos fiber types participants were exposed to. A job or exposure counted only if it lasted at least 2 years. Job titles, such as railway work, were also studied.
• Main results:
  • Among men, certain or very probable asbestos exposure was the only occupational exposure significantly linked to RCC: odds ratio 7.11 (95% CI 1.46 to 34.51). The table lists 11 exposed cases and 4 exposed controls. Because of missing data, the odds ratio came from a model based on 150 male matched pairs.
  • Among men, railway workers (engine drivers, traveling personnel, platform/sidings workers) had an odds ratio of 10.14 (95% CI 1.46 to 70.17). This was the only job title significantly linked to RCC after adjustment, with 11 cases and 2 controls in this job. The odds ratio came from a model based on 150 male pairs because of missing data.
  • Among men, the trend test for duration of employment was significant for managers (P = 0.04) and railway workers (P = 0.01), but not for metal workers (P = 0.12).
  • Among men, managers (odds ratio 3.59, 95% CI 0.82 to 15.59) and metal workers (odds ratio 2.21, 95% CI 0.99 to 5.37) almost reached statistical significance.
  • Among men, the increased odds for welding fume exposure were not statistically significant: odds ratio 5.67 (95% CI 0.78 to 41.31).
  • Among men, inorganic lead exposure showed an apparent negative association (odds ratio 0.13, 95% CI 0.02 to 0.73). The authors attributed this to the controls being hospital patients, some of them admitted for vascular disease.
  • Among men, high body-mass index was linked to RCC: odds ratio 4.91 (95% CI 1.56 to 15.5) for the third quartile and 4.42 (95% CI 1.48 to 13.18) for the last quartile.
  • Among women, the higher body-mass index group (25.4 and above) was linked to RCC: odds ratio 8.46 (95% CI 1.02 to 68.0). No job title was significantly linked to RCC in women.
  • Among men, current smokers had lower odds of RCC (odds ratio 0.32, 95% CI 0.12 to 0.79). The authors attributed this to bias from using hospital controls.
  • The authors repeated the analysis using only the 366 respondents who answered in person (198 cases, 168 controls). Among men, the associations for railway work, asbestos exposure and high body-mass index remained significant.
• The authors' conclusion: The authors concluded that railway workers working on or near trains may have an increased risk of RCC, possibly due to asbestos exposure. They called for further studies of railway workers, metal workers and managers.
• Limitations the authors state:
  • Controls were hospital patients, which can produce Berkson's bias. The authors used this to explain the unexpected results for smoking and alcohol.
  • Many comparisons were made, so some associations could have arisen by chance.
  • The study population was relatively small.
  • Further studies are needed to rule out that the railway worker finding was due to chance.
  • Matching cases and controls by residence can lead to overmatching on occupation, which can hide true associations.

Topics

Medical terms in this study, explained in our Lexicon: Carcinoma, Case-Control Study, Occupational History, Habit, Odds Ratio, confidence interval, Asbestos Exposure.

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