This randomized controlled trial evaluated the safety and efficacy of European mistletoe extracts (Helixor A and Iscador M Spez) as complementary therapy during chemotherapy in 95 breast cancer patients (stages T1–T3N0–N2M0). Patients received six cycles of cyclophosphamide, adriamycin, and 5-fluorouracil, with mistletoe extracts administered subcutaneously three times per week over