Risk Increases
A dose-response relationship was evident. For an increase in pesticide use of 2.5 kg/hectare over 11 years, the risk for pancreatic adenocarcinoma increased from 0.9% to 1.4%. “The increase is relatively small, but one must not forget that this risk applies to all of France,” said Dr. Brugel. Indeed, the risk appeared homogeneous across the entire territory.
This was the first study to explore this link at the national level. Although the association between the four identified factors and pancreatic risk was robust, the study had some limitations. It relied on the quantities of pesticides purchased to estimate the quantities used, Dr. Brugel pointed out.
The second study, PESTIPAC, was a case-control study conducted at the Reims University Hospital to explore the association between pancreatic adenocarcinoma and concentrations of organochlorine pesticides in fat and urine.
The study included 26 patients with pancreatic cancer who had abdominal surgery that allowed for adipose tissue sampling (minimum 10 g). Urine was collected in the morning on an empty stomach.
A control group was formed by including 26 other patients who underwent surgery for a benign abdominal condition such as gallstones or hernia, thus allowing for the same sampling. Individuals in both groups were matched for age and body mass index, two risk factors for pancreatic cancer.
Banned Substances
In total, 345 substances were searched for using chromatography and mass spectrometry. Analyses revealed the presence of five banned substances in all patients, while nine substances were found in half of the samples.
“Contamination is very widespread, both in patients with pancreatic cancer and in the controls,” said Dr. Brugel. Consequently, for this study, between-group comparisons of substances present in all individuals could not be performed.
After adjustment, an association with an increased risk for pancreatic cancer was nonetheless observed with four liposoluble substances: 4,4-DDE, mirex or perchlordecone, trans-nonachlor, and cis-nonachlor. All four substances are herbicides that have been banned for at least 30 years.
The study also aimed to assess the effect of pesticide presence in the body on survival after pancreatic cancer. The results showed no significant difference for overall survival or progression-free survival.
“Pesticides are a credible candidate to explain the increase in the incidence of pancreatic adenocarcinoma,” said Dr. Brugel. However, “if associations between pancreatic cancer and pesticides exist, they remain poorly understood, and it is difficult to establish clear causality.”
Further large-scale studies will be needed to confirm these associations. An evaluation of the general population’s exposure to banned substances also appears justified, according to the researchers.
This story was translated from the Medscape French edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.