An update from EMAS 2017: MHT and Cancer Risk

Earlier this year when we attended the EMAS conference in Amsterdam, the link between menopausal hormone therapy (MHT) and cancer risk was a hot topic for discussion. So what did we learn in Amsterdam?

On Day 1 of EMAS, Dr. Lydia Marie-Scemama discussed the fear patients have of breast cancer when taking MHT. How big is the risk? Research shows that menopause is the period where breast cancer can peak, and this is one of the biggest concerns for women who are considering taking MHT. Although studies have suggested that use of MHT will lead to an increase in breast cancer, data shows this is dependent on the type of MHT involved. Whilst some androgenic derived progestins seem to increase risk, evidence from the E3N and Finnish studies suggest that natural progesterone and dydrogesterone do not. Family history of breast cancer can also play a large part in treatment decisions and should be explored. Women with the BRCA1 gene have a 70% breast cancer risk whilst women with the BRCA2 gene have a 40-50% breast cancer risk. However evidence shows this risk is not amplified by the use of MHT as WHI studies have confirmed there is no increased risk of breast cancer in those with a family history of the disease. To see more from Dr Lydia’s session read our blog post: How to manage a patient’s fear of breast cancer and taking MHT.

Whilst breast cancer is one of the biggest concerns for women on MHT, other forms of cancer have also been linked to the treatment including endometrial and ovarian cancer.

Endometrial cancer (EC) is the most frequent female genital cancer in developed countries, accounting for around 6% of all cancers in women. Although there is no routine screening test for EC, prevalence of the condition has increased in recent years. The majority of women are diagnosed at an early stage so overall survival can be as high as 90%. Data from the Million Women Study has shown that post-menopausal women who use estrogen-only MHT have an increased risk of developing endometrial cancer. (1) For this reason, estrogen-only MHT is generally only offered to women post-hysterectomy. Evidence suggests that in the case of combined MHT the progestogen part of combined MHT can counteract the cancer-causing effects of the oestrogen part, when it comes to endometrial cancer, however this depends on the type of combined HRT used and may result in increased breast cancer risk. (2)

According to an extensive meta-analysis from the Collaborative Group on Epidemiological Studies of Ovarian Cancer, MHT may result in an increased risk of ovarian cancer. Researches stated "The findings that ovarian cancer risk is greatest in current users of hormone therapy, falls after use ceases, and varies by tumour type, strongly suggest a causal relationship," . It is thought that if the association is causal, one additional incidence of ovarian cancer will occur for every 1000 users among women who take HRT for 5 years, starting near age 50 years, and one extra ovarian cancer death will happen for every 1700 users.(2)

Although data does suggest there can be an increased risk of certain forms of cancer as a result of using MHT it is clear this is dependent on type of MHT, length of use and other risk factors. It is clear that any potential risk should be discussed with patients and explained before treatment begins.