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

Determination of DNA adduct count was performed in mononuclear cells during antihormonal treatment of perianal gland tumors. Materials and

Increased DNA adduct formation after long-term administration of tamoxifen shows its genotoxicity.

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.

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).