Organochlorine Pesticides Exposure as a Risk Factor for Breast Cancer in Young Women: A Case Control Study

Abstract

Background: Young women (< 40 years) constitutes about 10%–25% of total breast cancer cases in south-Asian women and an increase in incidence rates have been noted in the recent past. It is higher compared with their western counterparts, where rates of 5%–10% are reported. Younger women usually present with more aggressive tumor and poorer prognosis, suggesting that breast cancer in young women represents a distinct entity. Exposure to environmental estrogens such as organochlorine compounds in pesticides and industrial chemical has been proposed to be a risk factor for breast cancer. There is rampant use of pesticides in farming in south-Asian countries. However the associations between organochlorine compounds and breast cancer risk, reported in different studies has been inconsistent. Hence this study was planned with the objectives to assess the serum levels of organochlorine compound and the presence of other risk factors in north Indian population of young women diagnosed with breast cancer. Aim: To assess the serum level of organochlorine compounds and the other risk factors in north-Indian population of young women diagnosed with breast cancer. Methods: This case control study was conducted at UCMS & GTB Hospital, Delhi, India in 42 patients of breast cancer ≤ 40 years age and 42 age-matched-controls. The study subjects were evaluated for various known risk factors such as family history of breast or ovarian cancer, age of menarche, number of pregnancies and abortions, duration of breast feeding, oral contraceptive intake, obesity, benign breast disease & biopsy, etc. Study subjects were also evaluated for exposure to environmental pollutants by performing of assays of twelve different organochloride pesticides in their blood samples. Genetic analysis also done to look for polymorphisms of genes: BRCA1 at Q365R, BRCA2 at 6174delT and p53 at 216 location. Results: Significant association was seen between serum level of β- HCH, heptachlor, dieldrin, p,p'-DDE and risk of breast cancer in young women in our patient population. Significant association was also found between early age of menarche, obesity, BRCA 2 and p53 gene polymorphism as risk factors for breast cancer. Conclusion: Exposure to organochlorine pesticides could be an important modifiable risk factor, responsible for an increase in the rates of breast cancer in younger women. Polymorphism of p53 at 216 location & BRCA2 at 6174delT could be independent susceptibility marker in younger women with breast cancer. Larger studies are required to validate these results.