Organochlorines and 8-hydroxy-2 '-deoxyguanosine (8-OHdG) in cancerous andnoncancerous breast tissue: Do the data support the hypothesis that oxidative DNA damage caused by organochlorines affects breast cancer?

A study was conducted to test the hypothesis that oxidative DNA damage caus ed by exposure to organochlorines is an important risk factor in breast can cer. This is the first study that evaluates this hypothesis by measuring 8- hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, po lychlorinated biphenyl (PCB) congeners, and isomers of bis (4-chlorophenyl) -1,1,1-trichloroethane (DDT) and bis (4-chlorophenyl)-2,2,2-dichloroethane (DDE) in cancerous and noncancerous tissue. We measured these compounds in 44 primary tumors (cancerous) and 21 benign breast biopsy (noncancerous) ti ssues. Overall, no significant differences were observed in the level of th e organochlorines between the tissues. The median concentration for 8-OHdG was 10.5 fmol/mg DNA (1.7/10(5) deoxyguanosine residues), and 8.5 fmol/mg D NA (1.4/10(5) deoxyguanosine residues) in cancerous and noncancerous tissue , respectively. These values are similar to background levels. No significa nt differences were observed in 8-OHdG levels in cancerous versus noncancer ous tissue, and no correlation was demonstrated between the organochlorines and 8-OHdG. The data thus do not support the hypothesis that oxidative DNA damage caused by exposure to organochlorines is an important risk factor i n breast cancer.