DNA Adduct Assessment During Antihormonal Treatment of Perianal Gland Tumors With Tamoxifen in Male Dogs

Background/Aim: Determination of DNA adduct count was performed in mononuclear cells during antihormonal treatment of perianal gland tumors. Materials and Methods: Eight- to fifteen-year-old dogs with carcinoma (CAR Group; N=5), epithelioma (EPI Group; N=16) or adenoma (ADE Group; N=24) were used. The control group suffered from perineal hernia or rectal diverticulum (CTR Group; N=25). Blood was collected at baseline, and at one and six months after the beginning of the anti-hormonal treatment with tamoxifen (1 mg/kg of body weight). DNA adduct count was determined using autoradiography. Results: At baseline, DNA adduct count reached the highest value in the CTR Group, and the lowest in the EPI Group (p<0.05). Six-month-long therapy with tamoxifen resulted in a significant increase in the DNA adduct count by 78.7%, 221.5% and 198.3% in the ADE, EPI and CAR groups, respectively (p<0.05). Conclusion: Increased DNA adduct formation after long-term administration of tamoxifen shows its genotoxicity.