Detailed information and a list of references can be found in Chapter 3.5 of the FertiPROTEKT book, “Indications and fertility preservation methods for oncological and non-oncological disorders”, which can be downloaded free of charge.
GnRH agonists (GnRHa) are drugs which temporarily prevent the release of the hormones LH and FSH from the pituitary gland, which normally stimulate oocyte maturation and hormone production in the ovaries. Suppression of hormone production in the ovaries should reduce the sensitivity of the ovarian tissue to chemotherapy and therefore the likelihood of damage. The use of GnRHa has long been critically discussed. The reasons for this are that a protective effect has not been definitely proven and the — also unproven — assumption that the reduction in hormone production in the ovaries with hormone-dependent tumours (e.g., some forms of breast cancer) could also reduce the desired effect of chemotherapy on tumour cells.
GnRHa are usually administered subcutaneously as a 1- or 3‑month depot injection about a week before chemotherapy. The injection is then repeated as needed so that the effect lasts for the duration of chemotherapy.
Birth control pills are not further considered here, since no major current studies are available which have analyzed their efficacy with regard to fertility preservation to a sufficient extent and quality.
Most summaries of studies since 2011 show that by using GnRHa, the probability of a permanent suppression of ovarian function after chemotherapy is considerably reduced. .
Some studies also describe a higher pregnancy rate after the end of treatment in women who received GnRHa simultaneously.
GnRHa can cause menopausal symptoms such as hot flushes, etc. The conceivable loss of bone density when used for > 6 months is usually irrelevant because the duration of chemotherapy does not normally exceed this length of time.
There is currently no evidence that GnRHa could theoretically decrease the effectiveness of chemotherapy in hormone receptor-positive tumours.
The cost of GnRHa over one month is about 180 € and the total cost alongside 6 months of ongoing chemotherapy, for example, is approximately 6 x 180€. The costs are only covered by health insurance in exceptional cases.
GnRHa are injected subcutaneously for the first time about a week before chemotherapy. The drug is given repeatedly during the course of chemotherapy, so that its effect lasts for about 1–2 weeks after the end of the last chemotherapy.
If chemotherapy must be started within less than a week in urgent cases, the effect of GnRHa can be supported by the additional short-term use of a related drug (so-called GnRH-antagonists). Chemotherapy can then, for example, begin on the day after the first injection.