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Endocrine Therapy

Patients who have Estrogen Receptor and Progesterone Receptor positive breast cancers may be offered endocrine therapy. It is more than 100 years since Beatson reported the first successful ovarian ablation used in the treatment of breast cancer.

The most common treatment regimes are selective oestrogen receptor modulators (e.g. Tamoxifen) which can be used in pre and postmenopausal women. Postmenopausal women may also be treated with an aromatase inhibitor. Some of these drugs are also recommended to women that have a high lifetime risk of breast cancer to reduce their risk by up to 40 percent.

There is new evidence to indicate that 10 years treatment with endocrine therapy is associated with an improvement in survival. Previously it was standard of care for women to take endocrine therapy for 5 years post breast cancer diagnosis.

Recently, a large international clinical trial has found new treatment options to reduce the risk of breast cancer recurring in some young women with hormone receptor positive breast cancer. The SOFT trial recruited more than 3000 premenopausal women with hormone positive breast cancer worldwide including in Australia. It compared the current standard of treatment for premenopausal women with ER-positive cancer tamoxifen alone with 2 new treatments, tamoxifen combined with some form of ovarian suppression or exemestane (Aromasin) combined with ovarian suppression.

Ovarian suppression aims to stop ovaries producing oestrogen which is a driver for hormone positive breast cancer. The ovarian suppression can be in the form of removal of the ovaries and fallopian tubes via keyhole surgery with bilateral laparoscopic Salpingectomy-oophorectomy or with the use of medications such as Zoladex to inhibit the reduction of oestrogen from the ovaries.

The patients requiring oophorectomy as part of their breast cancer management can have this easily arranged and performed by one of the gynaecologist at the Specialist Breast Cancer Surgery.

The SOFT trial also showed that adding ovarian suppression to tamoxifen reduced breast cancer recurrence rates for some young premenopausal women but not all. The most notable improvements were in women aged under 35. Women who also received adjuvant chemotherapy and were still menstruating and thus producing oestrogen from their ovaries post chemotherapy also had improved outcomes if ovarian suppression was used. Women in this group who received exemestane with ovarian suppression had better results than those who received tamoxifen with ovarian suppression.

Very young women with hormone receptor-positive breast cancer are known to have a high risk of breast cancer recurrence and therefore the results of the SOFT trial will change recommendations for very young women. The addition of ovarian suppression to tamoxifen, however, has increased side effects with an increase in hot flushes, sweating, insomnia, and some sexual side effects such as a dry vagina and low libido. Women who took exemestane also reported more joint aches and changes in the bone density. Obviously, women who had a laparoscopic (keyhole surgery) to remove their ovaries and fallopian tubes will not be able to regain their fertility post breast cancer treatment and therefore for very young ladies that wish to maintain some fertility they may wish to undergo treatment with Zoladex instead of having surgical removal of the ovaries and tubes.