Tamoxifen predisposes to :
Endometrial cancer
Ovarian cancer
Cervical cancer
Vaginal cancer
In Breast Cancer although tamoxifen improves the survival period, it causes endometrial hyperplasia and cancer, and requires regular monitoring with ultrasound study of endometrium and endometrial biopsy. Reference: Shaw's Textbook of Gynaecology 16th edition page no 540
Gynaecological oncology