4.3. Rat DMBA Induced Mammary Tumor Model

Female Sprague Dawley rats (Charles Rivers) were administered a single oral gavage of 50 mg of 7,12-Dimethylbenz[a]anthracene (DMBA) from Thermo Fisher (SKU: AC408181000) dissolved in mineral oil when they reached an age of 50 days. Rats were palpated for tumors twice weekly for 5 months. When a palpable tumor nodule was identified (~1000 mm³ in volume), the rat was randomized to receive either ECE or saline injections. After identifying the initial tumor, 200 µL of either saline or ECE was injected directly into the tumor under isoflurane anesthesia for 4 weeks (on study days 0, 7, 14, and 21). On day 30 of the study all tumors were excised. If a tumor reached the tumor burden limit of 5000 mm³ before day 30, the rat was euthanized by CO₂ inhalation and bilateral thoracotomy and tumors were collected at that time for histology.