Vaginal oestrogen therapy after breast cancer: Is it safe?

Abstract

The increasing number of breast cancer patients who suffer from menopausal symptoms is mainly due to the extensive use of adjuvant treatments in the younger women. Both short and long-term side effects of oestrogen deficiency may severely impact on the quality of life of these women and should not be underestimated. Hormonal treatments are contraindicated in breast cancer survivors mainly due to the concern that dormant micrometastases may be stimulated to grow. Alternative non-hormonal remedies are now available to alleviate symptoms and to prevent chronic diseases associated with oestrogen deficiency. Urogenital atrophy is an important consequence of oestrogen deprivation that can be effectively treated by vaginal estrogens, although systemic absorption occurs with conventional doses. Preliminary data suggest that much lower doses of vaginal estrogens can alleviate urogenital atrophy without influencing serum estrogenic levels. Further research is warranted to confirm whether vaginal estrogens are safe in symptomatic breast cancer patients who are non-responsive to alternative treatments.

Introduction

Menopausal symptoms are a major problem for an ever increasing number of breast cancer survivors of our society. In the year 2000 over a million women worldwide were diagnosed with breast cancer and this number is expected to almost double by 2050 [1].

The good news is that mortality has started to lower in developed countries for the first time in history since 1990. The persistence of this trend, with a stable 2.2% yearly decrement in the mortality rate, and the dramatic increase of lung cancer incidence, account for the fact that lung cancer has overtaken breast cancer as the leading cause of cancer death in the female US population. Nevertheless, breast cancer still represents 32% of all female cancers and longer survivals translate into higher overall numbers of women experiencing treatment-related side effects [2]. Furthermore, since the first release of the Oxford overview, the number of patients undergoing hormonal and/or cytotoxic treatment has been steadily increasing both in the pre- and in the post-menopausal age [3]. The diffusion of adjuvant treatments, together with longer survivals, has undoubtedly determined an increase of short and long-term side effects, some of which are directly related to oestrogen deficiency.

Since hormonal therapy (HT) is currently contraindicated in breast cancer patients, alternative remedies have been developed to alleviate systemic (hot flashes) and local (mainly urogenital atrophy) acute effects of oestrogen deprivation. In particular, the vaginal administration of estrogens is very effective for preventing and treating urogenital atrophy. Nevertheless, even this route of administration may cause systemic absorption of estrogens and thus its safety in breast cancer patients is debated. In order to clarify this issue, both the relevance of menopausal symptoms and the evidence for and against vaginal HT in breast cancer survivors will be reviewed in the light of personal experience and from the available literature data.