An Association Between Respiratory System Cancers and Sugarcane Related Occupation in Louisiana

Our plain-English summary of An Association Between Respiratory System Cancers and Sugarcane Related Occupation in Louisiana, by A.W. Voors (1980).

The study

• Author: A.W. Voors
• Published: Draft, P.1-12. March 25, 1980. Includes a Letter to Dr. Paul Kotin.
• Type of article: Report
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1980 draft paper described a retrospective study of people who died of respiratory system cancers (RSC) in 10 parishes of southern Louisiana from 1971 to 1977. Of 815 such deaths, the researchers interviewed relatives of 274. Of these 274, 128 (47%) had worked at least two years in sugarcane-related jobs (farming, bagasse handling or refinery work), yet their death certificates listed only 11 (4%) as having sugarcane-related occupations. Among 128 matched controls who died of other causes, 22 (18%) had held such jobs. In the matched comparison, sugarcane farm work had an estimated relative risk of 3.80 (p less than 0.0001), and bagasse handling was also significantly elevated. No other occupation showed such a relationship. A summary estimate combining age and smoking groups indicated a greater than four-fold risk for sugarcane farming. The authors reported finding two mesotheliomas among the deceased sugarcane farmers. They concluded that their data indicate an association between sugarcane farming and death from RSC. They noted the relationship could be noncausal, reflecting other factors.

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: Retrospective matched case-control study based on death certificates and interviews with relatives of the deceased
• Who was studied: 815 people who died of respiratory system cancers in 10 nonurban parishes of southern Louisiana, 1971-1977. Relatives of 274 were interviewed, and 128 of these cases were matched to 128 controls who died of other causes (matched for year of death, age, sex, race and parish).
• Exposure: Sugarcane-related occupations held for at least two years: sugarcane farming, bagasse handling and sugar refinery work. Cigarette smoking (daily pack-years) and alcohol intake were also asked about.
• Main results:
  • Of the 274 cases whose relatives were interviewed, 128 (47%) had worked at least two years in sugarcane-related occupations; their death certificates listed only 11 (4%) as having such occupations.
  • Among the 128 matched controls, 22 (18%) had been employed in sugar-related occupations.
  • In the matched-pair analysis, 43 of 128 cases and 15 of 128 controls had worked as sugar farmers, farm managers or laborers (estimated relative risk 3.80, p less than 0.0001).
  • Bagasse handlers also had a significantly elevated estimated relative risk (p less than 0.05), as did all sugarcane occupations combined (p less than 0.0001).
  • No other occupation showed such a relationship with RSC.
  • Smokers of 41 or more daily pack-years, compared with those of 40 or fewer, had an estimated relative risk of RSC of 1.93 (p less than 0.05).
  • The relative risk for sugarcane farmers rose with increasing smoking level, from 2.50 to 5.61, but the increase was not statistically significant (p greater than 0.05).
  • A summary odds ratio combining the age and smoking groups indicated a greater than four-fold risk of RSC death for sugarcane farming (p less than 0.01).
  • No association between alcohol intake and RSC was observed.
  • Among the deceased sugarcane farmers, the authors found two with mesothelioma, which they described as a higher incidence than expected by chance (details in a manuscript in preparation).
  • Of 342 RSC death certificates checked against medical records, 326 (95%) had a clinical diagnosis consistent with RSC.
• The authors' conclusion: The authors concluded that their data indicate an association between sugarcane farming and death from respiratory system cancers in Louisiana.
• Limitations the authors state:
  • The size of the population at risk could not be estimated because occupational data for the state before 1970 are incomplete.
  • Analyzing individuals instead of matched pairs in the age- and smoking-stratified analysis may have underestimated the odds ratio.
  • The association could be noncausal, reflecting genetic, environmental or other unidentified factors linked to both occupation and mortality.
  • In the cover letter, the author states that the matched-pair analysis had to be abandoned for the smoking-stratified analysis because of small numbers.

Topics

Medical terms in this study, explained in our Lexicon: Death Certificate, Relative Risk, Mesothelioma.

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