Hormone Replacement Therapy (HRT) And Cancer
By Miss Lita Chew, Manager, Oncology Pharmacy, NCC
Synthetic forms of the female sex hormones, oestrogen and progesterone, are often prescribed to ease symptoms of menopause – a condition that results from a normal age-related decline in natural hormone production. This form of treatment is called hormone replacement therapy (HRT).
There are several schedules for taking HRT in pill form. If you are taking oestrogen everyday for a set number of days, add progesterone for 10 to 14 days, and then stop taking one or both for a few days, you will experience regularly monthly bleeding like a light menstrual period. On the other hand, if you take oestrogen and progesterone together every day of the month, your monthly periods may cease after a few months of treatment.
Taking HRT for a few years can relieve menopausal symptoms such as hot flashes and sweats. Long term HRT treatment may prevent osteoporosis and improve blood cholesterol levels. Whether HRT can also reduce dementia and increase longevity (due to reduced heart attacks and stroke) remains uncertain, despite many claims for this kind of benefit.
Like any drug therapy, HRT has potential side effects. These include nausea, fluid retention, breast tenderness, cramping, irritability, depression and vaginal bleeding. The exact profile of side effects varies with the relative dose of oestrogen versus progesterone, so changing the medication can often improve the tolerability of treatment. Of greater concern are the risks below:
Endometrial cancer. When used in high doses and for long periods and without progesterone, oestrogen supplements increase the risk of developing endometrial cancer. For this reason most doctors now prescribe HRT comprising lower doses of oestrogen and progesterone for women who still have a uterus. On the other hand, women who have had their uterus removed can safely use oestrogen alone.
Breast cancer. Long term HRT containing oestrogen has an increased risk of breast cancer. Therefore, HRT should only be prescribed for sound symptomatic and / or preventive reasons; it should not be regarded as a “fountain of youth”.
Blood clots . Another HRT-induced risk relates to the development of blood clots (thrombosis) in veins or lungs. The risk is higher for HRT-treated women who are smokers, or who has a family history of blood clots.
Can you still take HRT if you have previously been treated for cancer?
This question is particularly relevant to younger breast cancer patients who are experiencing menopausal symptoms, often triggered by their cancer treatment. For patients who are taking tamoxifen or other anti-oestrogenic treatments to reduce the risk of breast cancer relapse, it can be difficult for doctors to prescribe oestrogen-containing medications at the same time. If your symptoms are severe, however, it may be worth discussing with your doctor the pros and cons of continuing (or discontinuing) the medication causing the symptoms. The expected benefit may be small. However, if you are not on tamoxifen and if your previous cancer did not contain hormone receptors, it is possible to have a short course of HRT – provided that you continue to have a mammographic screening for new tumours. |
