Established risk factors for
breast cancer explain
breast cancer risk only partially. Organochlorines are considered to be a possible cause for
hormone-dependent
cancers. A hospital-based case-control study, the first from India, was conducted among 50 women undergoing surgery for
breast disease to examine the association between organochlorine exposure and
breast cancer risk. Blood,
tumor, and surrounding adipose tissue of the breast were collected from the subjects with benign (control) and malignant breast (study) lesions and analyzed to determine organochlorine
insecticides using a gas-liquid chromatograph equipped with an electron capture detector. The alpha, beta, gamma, and delta isomers of
hexachlorocyclohexane (HCH), p,p'-dichlorodiphenyltrichloroethane (
DDT),
o,p'-DDT,
p,p-dichlorodiphenyldichloroethylene, and p,p'-
dichlorodiphenyldichloroethane were frequently detected in three specimens. Total HCH and total
DDT levels were higher in the blood of the study group (25 cases) than in those of the controls (25 cases) with only
gamma-HCH being significantly different (P<0.05). However, both total HCH and total
DDT were higher in the
tumor tissues of the controls than in those of the study group;
gamma-HCH was significantly different (P<0.05). The level of total HCH (
alpha-HCH was significantly different, P<0.05) was higher in the breast adipose tissue of the study group, whereas total
DDT was higher in the breast adipose tissue of the control group. The distribution of known confounders of
breast cancer including age, body mass index, age at menarche and menopause, duration of breast feeding, and family history related to
breast disease did not differ significantly between benign and malignant groups. This pilot study with limited statistical power does not support a positive association between exposure to organochlorines and risk of
breast cancer but paves the way for a larger Indian study with greater statistical power encompassing different regions of the country to enable statistically sound conclusions.