Which statement about estrogen-only vs combined MHT is true?

• A. Estrogen alone can increase the risk of uterine cancer; combined therapy includes progestin to reduce this risk
• B. Combined therapy has no effect on uterine cancer risk
• C. Estrogen alone eliminates uterine cancer risk
• D. Progestin alone is sufficient to prevent cancer

Answer: (A)

Estrogen stimulates the uterine lining, so in women who still have a uterus, unopposed estrogen can raise the risk of endometrial hyperplasia and cancer. Adding a progestin counteracts that effect by changing the endometrium and promoting regular shedding, which lowers the cancer risk. That’s why estrogen-only therapy is reserved for women who have had a hysterectomy; for those with a uterus, combining estrogen with progestin reduces the risk of uterine cancer compared with estrogen alone. The idea that combined therapy has no effect on uterine cancer risk isn’t accurate, since it lowers risk though it isn’t zero. Estrogen alone does not eliminate risk, and progestin alone isn’t a substitute for estrogen when symptoms of menopause require estrogen therapy.