Environmental estrogens increase risk for prostate cancer
MedWire News: Exposure to chlordecone, an insecticide with estrogenic properties, increases a man’s risk for prostate cancer, according to a study involving West Indian men.
The researchers also found that men who carry variations in the gene encoding chlordecone reductase (CHDR) have a further increased risk for prostate cancer after exposure to the insecticide.
“This is the largest study to have investigated the effects of organochlorine compounds on prostate cancer risk through the evaluation of exposure by biologic measurement,” write Luc Multigner from the National Institute of Health and Medical Research in Guadeloupe, French West Indies, and colleagues.
Chlordecone was used extensively between 1973 and 1993 in the West Indies, explain the researchers, who hypothesize that its carcinogenic and hormonal properties may have increased the development of prostate cancer in the area, where prevalence is high.
Their study included 623 men with prostate cancer recruited from 2004–2007, and 671 healthy controls recruited from 2005–2006. Exposure to chlordecone was analyzed via men’s blood plasma concentration levels or their cumulative exposure index, based on years of exposure.
Chlordecone was detected in the plasma of 68.7% of men with prostate cancer and 66.8% of controls.
The team found that after adjustment for age, plasma lipid concentration, waist-to-hip ratio, and a history of prostate cancer screening, the risk for prostate cancer increased with increasing plasma chlordecone levels. Men in the highest tertile (>0.96 µg/ml) had a significant 1.77-fold higher increased risk for prostate cancer compared with those with levels at the limit of detection (≤0.25 µg/ml).
After the same adjustment, men in the highest quartile for cumulative exposure index also had a significant 1.73-times higher risk for prostate cancer compared with those in the lowest exposure group.
The researchers then genotyped the men for the single nucleotide polymorphisms rs3829125 and rs17134592, variants of the CHDR gene. They hypothesized that the prostate cancer-causing effects of chlordecone would be stronger in men carrying these alleles because of reduced resistance to its toxicity.
The results, published in the Journal of Clinical Oncology, showed that men with plasma concentrations of chlordecone above the limit of detection had a 5.23-fold higher risk for prostate cancer if they had either of the variant alleles than if they had neither. However, this risk difference was nonsignificant.
“These findings require further investigation,” conclude Multigner et al.
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By Sarah Guy