Randomization and blinding
ONCOLOGY, WITHDRAWAL BLEEDING
The randomization scheme in this study was computer-generated using blocks of four, with group assignments concealed in sealed envelopes. The sonographer was blinded to the assignments. Participants were randomized in a 1:1 ratio to receive a daily dosage of CC (50 mg; Ovamit, Remedica Ltd, Limassol, Cyprus) in combination with letrozole (2.5 mg; Fresenius Kabi Oncology Ltd, Kolkata, India) or CC alone (50 mg) daily. Both treatment regimens were taken from days 3 through 7 of the menstrual cycle. Patients with long menstrual cycles were prescribed an oral progestogen to induce withdrawal bleeding. The progestogens administered were medroxyprogesterone acetate (10 mg daily; Provera; Pfizer, New York, NY, USA) or norethisterone acetate (5 mg daily; Primolut N; Bayer Thai Co Ltd, Bangkok, Thailand) for 7–10 days.