If the tumor has receptors for estrogen and progesterone (proteins present on the surface of some cancer cells), it is necessary to undergo a “hormonal” or anti-estrogen therapy. If the patient is in the fertile or premenopausal phase, the analogues of GNRH or hormones that block ovarian activity are added to these drugs. They are administered every month or every three months according to the intramuscular formulations. In addition to blocking ovarian activity, these drugs protect the ovaries to be able to reactivate once the therapy is finished and to be able to consider the recovery of future fertility.
How Do They Work?
The female hormones, estrogen and progesterone, are able to stimulate the growth of breast cancer cells. Hormone therapy or endocrinotherapy consists of pharmacological treatments that block the action of female hormones on cancer cells, preventing their development. in rapid growth, not only of cancerous cells (hair, mucous membranes, etc.) for which hormone therapy is associated with fewer side effects. Adjuvant hormone therapy is usually given for 5 years at the end of chemotherapy or soon after surgery, depending on the histological and biological characteristics of the cancer cells.
Tamoxifen is the “historic” hormone therapy for the treatment of breast cancer. It was registered in Italy over 30 years ago and has long been considered the reference drug. It works by competitively binding to estrogen receptors. It has been shown to be effective in reducing the risk of relapse in women with estrogen receptor positive breast cancer. It is taken orally, at a dose of 20 mg once a day. It can be taken at any time of the day, both before and after meals. It is advisable to choose a time and to keep it constant.
It can induce premature menopause. The most common side effects are:
- hot flashes
- weight gain and water retention
- vaginal dryness
- mood swings and a tendency to melancholy
Some of these side effects – such as hot flashes, tendency to get fat, and melancholy / depression – are highly dependent on personal history. More rarely it can cause the onset of endometrial cancer (the mucosa that lines the inside of the uterus but in oncological checks the oncologist prescribes an endovaginal pelvic ultrasound every six to eight months for the evaluation and measurement of the thickness of the endometrium It can predispose the patient to the risk of thrombosis in the lower limbs but the oncologist can subject the patient to an ultrasound Doppler examination of the lower limbs It can also increase the risk of stroke and cataract
Aromatase inhibitors work “upstream”, preventing the aromatase enzyme from producing estrogen. This reduces the amount of estrogen circulating in the body that can reach the cancer cells. Aromatase inhibitors are reserved for women already in menopause, since in this subpopulation the production of estrogen by the ovaries is reduced until it disappears. But estrogen is not entirely absent: in the muscles, liver and adipose tissue, there is still a production of estrogen and aromatase inhibitors act precisely in these production sites.
These drugs have been shown to be superior to Tamoxifen in estrogen receptor positive patients. Aromatase inhibitors are usually associated with mild or moderate side effects. Most adverse reactions can be attributed to the normal physiological consequences of estrogen suppression, such as hot flashes, arthralgia and myalgia (joint or muscle pain). Aromatase inhibitor treatment may also be associated with osteoporosis and bone fractures, a well-controlled side effect with adequate assessment of bone density and osteoporosis preventive therapy if necessary.
The aromatase inhibitors used today are tablets that are taken once a day, one tablet only, and are: Anastrazole – Letrozole – Exemestane. Today the use has also been validated in younger women if the minus pause is induced pharmacologically.
These drugs are also used in hormone-responsive metastatic disease, which is when cells have hormone receptors on the surface.
LHRH analogues are drugs indicated for premenopausal women to completely inhibit the activity of the ovaries and induce pharmacological menopause, which has a temporary duration and usually resumes the menstrual cycle from a few months to a year after the end of treatment. They are administered intramuscularly, once every 28 days or every 3 months according to the preference and tolerance of the woman. They are typically given premenopausally with Tamoxifen or Exemestane. On their own they can be used for the preservation of ovarian function during chemotherapy in young women requiring preservation of fertility.
The most common side effect during LHRH analog therapy is hot flashes. Cases of headache, nausea, vomiting, loss of libido and skin pigmentation have also been reported during treatment with these drugs. Prolonged use of LHRH analogues can induce bone loss (osteoporosis).