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Breast Cancer - ovarian function, oestrogen, fertility and the menopause

Breast cancer is the most common form of malignancy in women. The cancer may be non-invasive at diagnosis - ductal carcinoma in situ - where it remains confined to the ducts. However in most patients it is invasive, it may have spread beyond the immediate site of origin at diagnosis. The aim of treatment is always to reduce mortality, increase progression-free and disease-free survival and improve the quality of life. The management of patients involves surgery, radiotherapy and drug therapy, or a combination of these.

Drug therapy (chemotherapy) aims to reduce the risk of recurrence, invasion and metastases. In advanced disease - where cure is not expected treatment aims to induce remission, prolong disease-free survival, to relieve symptoms and improve the quality of life. Chemothrapy can be given after surgery (adjuvent chemotherapy) or before surgery (neoadjuvent chemotherapy) with the goal of reducing tumour size (downsize the tumour) to make breast-conserving surgery possible.

Oestrogen is important for the treatment of breast cancer in a number of ways.

1. Breast cancers can grow under the influence of ovarian oestrogen

Normal breast cells, that are not cancerous, can grow under the influence of oestrogen (estrogen). Breast cancer cells that maintain the oestrogen (estrogen to some) receptor (ER+ breast cancer*) can continue to use oestrogen as a growth factor. In pre-menopausal women, who continue to make oestrogen from their ovaries, it is important to block that oestrogen acting on breast cells, particularly breast cancer cells that might have not been removed at surgery and/or not damaged or destroyed by chemotherapy and/or radiotherapy, because the oestrogen may make those cells grow and proliferate causing recurrent disease. Tamoxifen is an oestrogen receptor blocker that is used in the management of breast cancer in pre-menopausal women.

2. Breast cancers can grow under the influence of locally produced oestrogen

Small amounts of oestrogen are produced all round the body by a process called aromatisation. If there is no ovarian oestrogen ER+ breast cancer can be effectively treated by aromatase inhibitors like anastrazole, letrozole and exemestane hence decreasing local oestrogen production in the cell. These drugs cannot be used in pregnancy, breast feeding or if pregnancy might occur unless there is secure contraception as these drugs can damage the developing baby. Pre-menopausal patients who have had disease progression despite tamoxifen may be prescribed drugs (goserelin) to suppress their own ovaries to enable them to take aromatase inhibitors..

3. Breast cancer chemotherapy may cause temporary or permanent ovarian failure.

The question of ovarian function and how it relates to treatment options is further complicated by the fact that adjuvant or neoadjuvant chemotherpy can damage the ovaries temporarily, or permanently. The oncologist (cancer specialist) in this situation may need to consult with an endocrinologist, or a specialist gynaecologist, to determine what the state of the ovaries are, and in particular what can be used - tamoxifen, aromatase inhibitor alone or an aromatase inhibitor with goserelin.

Temporarily affecting ovarian function might cause a picture indistinguishable from the menopause (below) but mean that the patient can still be fertile in the months and years to come, it might mean that the patient and oncologist need to consider how to manage the patient during pregnancy, it might mean that ovarian oestrogen can and will be made in increasing amounts affecting the choice of therapy.

Permanently affecting ovarian function, especially if it induces a menopause removes some of these difficult decisions around changing therapy, but brings new long term concerns about the consequences of the menopause - fertility, sense of well being, libido, sexual function, vaginal health and even cardiovascular and skeletal health.

No decisions should be made about a patients health without them, and no patient should be asked to make a decision about their health without adequate information and time for that decision.

*There are other receptors that are important for breast cancer including the progesterone receptor and the HER-2 receptor.

Every effort is made to ensure that this health and medication advice is accurate and up to date. It is for information only and supports your consultation it does not obviate the need for that consultation and should not replace a visit to your doctor or health care professional.

The written advice is general in nature and in is not specific to individual patients and Dr Philip Kelly cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages contained in any external link.

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