Hormone replacement therapy (HRT) is a treatment used to relieve symptoms of menopause such as hot flashes, night sweats, sleep disturbances, mood changes, and vaginal dryness.

HRT works by supplementing estrogen and progesterone hormone levels in the body, which decrease naturally during menopause.

While HRT is an effective method for alleviating menopausal symptoms, research has shown that it may increase the risk of certain cancers.

In this article, we will explore the link between HRT and cancer risk, as well as the factors that may affect this relationship.

Types of Hormone Replacement Therapy

There are two main types of HRT: estrogen-only therapy (ET) and combined estrogen-progestin therapy (EPT).

ET is typically recommended for women who have had a hysterectomy (removal of the uterus). The use of estrogen alone in these women has been shown to have a lower risk of breast cancer than EPT.

However, ET has been linked with an increased risk of endometrial cancer (cancer of the lining of the uterus).

EPT is recommended for women who still have a uterus. This therapy combines estrogen with progesterone, a hormone that helps protect the lining of the uterus from the effects of estrogen.

However, EPT has been shown to have an increased risk of breast cancer compared to ET.

HRT and Breast Cancer Risk

Breast cancer is the most common cancer in women worldwide, accounting for nearly 30% of all cancers in women. Several studies have found that women using HRT, especially EPT, have an increased risk of breast cancer.

The Women’s Health Initiative (WHI) study is the most well-known study investigating the link between HRT and breast cancer risk.

The WHI study was a large, randomized clinical trial that enrolled over 16,000 women between the ages of 50 and 79. The study found that women taking EPT had a 26% increased risk of breast cancer compared to women not taking HRT.

However, the study also found that the number of breast cancer cases was small, and the overall risk of breast cancer was relatively low.

Other studies have also found a positive association between HRT and breast cancer risk.

One study published in the Journal of the National Cancer Institute found that women using EPT for five years or more had a 68% increased risk of breast cancer compared to women who never used HRT.

HRT and Endometrial Cancer Risk

Endometrial cancer is the most common gynecologic cancer in women in the United States. The risk of endometrial cancer increases with age, obesity, and exposure to estrogen without progesterone.

Women who have had a hysterectomy (removal of the uterus) and use ET have an increased risk of endometrial cancer compared to women not taking HRT. ET is recommended only for women who no longer have a uterus.

However, EPT has been shown to decrease the risk of endometrial cancer in women with a uterus. This is because progesterone helps protect the lining of the uterus from the effects of estrogen.

Women taking EPT have a lower risk of endometrial cancer compared to women taking ET or not taking HRT.

HRT and Ovarian Cancer Risk

Ovarian cancer is a rare but deadly cancer that affects the ovaries. Women who use HRT, especially EPT, have been shown to have an increased risk of ovarian cancer. The risk of ovarian cancer increases with the duration of HRT use.

A study published in the Journal of the National Cancer Institute found that women taking EPT for five years or more had a 46% increased risk of ovarian cancer compared to women who never used HRT.

Factors Affecting the Link Between HRT and Cancer Risk

Several factors may affect the link between HRT and cancer risk, including:.

Age
Duration of HRT use
Type of HRT
Previous history of cancer
Family history of cancer
Lifestyle factors such as obesity and smoking

Women who start HRT at a younger age and use it for a shorter duration may have a lower risk of cancer compared to women who start HRT at an older age and use it for a longer duration.

Women using ET may have a lower risk of breast cancer than women using EPT. Women with a previous history of cancer or a family history of cancer may have an increased risk of cancer with HRT use.

Conclusion

Hormone replacement therapy is an effective treatment for menopausal symptoms but has been associated with an increased risk of certain cancers, including breast, endometrial, and ovarian cancer.

Women considering HRT should discuss the potential risks and benefits with their healthcare provider to determine the best course of treatment for their individual situation.

In order to minimize the risk of cancer, women may consider using the lowest effective dose of HRT for the shortest duration possible.

Women should also maintain a healthy lifestyle by eating a well-balanced diet, exercising regularly, and avoiding smoking and excessive alcohol consumption.