The Inhibitory Effect of Selenium Supplementation on Tumor Progression in a DMBA-Induced Breast Cancer Model in Wistar Rats

Background: Breast cancer remains a significant global public health concern, necessitating the ongoing exploration of novel preventive and therapeutic strategies. Selenium supplementation has been proposed as a potential chemopreventive agent, yet its efficacy lacks robust in vivo validation. Aims: This study aimed to evaluate the chemopreventive potential of selenium supplementation and its effect on tumor progression in a 7,12-dimethylbenzaanthracene (DMBA)-induced breast cancer model in Wistar rats. Methods: Twenty-four adult female Wister rat were allocated into four experimental groups (n=6): Control (vehicle only); DMBA (carcinogen control); DMBA + Se 200 µg/kg; and DMBA + Se 400 µg/kg. Mammary tumors were induced via a single intragastric administration of DMBA (80 mg/kg). Over a 23-week period, hematological, biochemical, and histopathological analyses were conducted. The volume of excised mammary tumors was measured post-sacrifice. Results: Supplementation with selenium at a dose of 400 µg/kg resulted in a statistically significant reduction in mean tumor volume (0.13 cm³) compared to the DMBA-only group (1.32 cm³). Concurrently, this high-dose group exhibited significant amelioration in serum levels of specific biochemical markers including aspartate aminotransferase (AST), urea, and creatinine. Histopathological assessment further supported these findings, revealing a more preserved mammary tissue architecture in rats receiving the high-dose selenium. Conclusions: While selenium supplementation at 400 µg/Kg demonstrated a significant inhibition effect on tumor progression and conferred hepatorenal protection, a definitive chemopreventive effect against DMBA-induced carcinogenesis was not established. These results indicate that selenium may function as a therapeutic modulator rather than a primary preventive agent in this model. Further investigation employing higher doses and alternative administration regimens is warranted to elucidate its full chemopreventive potential. Keywords: Breast cancer; Selenium; DMBA; Chemoprevention; Tumor Progression; Wistar rats.