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Some women report worse side effects after ovarian suppression

In sub-study of SOFT trial, women given tamoxifen plus ovarian suppression reported higher rates of certain menopausal symptoms than women given tamoxifen alone


The women reported their symptoms as part of the Suppression of Ovarian Function Trial (SOFT), an international study that found blocking ovarian function may lower the risk of cancer returning for some young women. The findings on symptoms were analyzed in this sub-study.



The SOFT trial was designed to evaluate tamoxifen plus ovarian suppression in premenopausal women with early-stage, hormone receptor-positive breast cancer. It also looked at how using the aromatase inhibitor exemestane (Aromasin) plus ovarian suppression compared with tamoxifen plus ovarian suppression and tamoxifen alone. Women in the trial may have had chemotherapy before joining. The study found exemestane plus ovarian suppression to be the more effective of these treatments for women who had received chemotherapy but had not gone through menopause.

The hormone estrogen makes some types of breast cancer grow. Premenopausal women normally produce estrogen in their ovaries. When these women have breast cancer that grows in response to estrogen they may be given tamoxifen, a hormonal therapy that blocks the cancer cell’s estrogen receptors. Some also may have ovarian suppression to lessen the amount of estrogen the ovaries make. In the SOFT trial, the ovaries were suppressed using either the medicine triptorelin (Trelstar), surgery to remove the ovaries, called oophorectomy, or radiation to the ovaries.

In this analysis, the SOFT researchers collected information from participating women on hormone-related side effects and the impact those had on their quality of life across different treatment types. The researchers looked at the results from women treated with tamoxifen alone, with tamoxifen plus ovarian suppression, and with exemestane plus ovarian suppression.



Participants from different treatment groups reported on quality of life measures including health, mood and any side effects experienced at the start of the study. This baseline survey was followed by new reports completed at their doctor’s office every 6 months for the next 2 years, and then once a year for another 4 years.

The analysis included 1,722 premenopausal women with early-stage, hormone receptor-positive breast cancer. They had a median age of 43 years. About half – 55 percent – had prior chemotherapy.



Compared with the tamoxifen alone group, women who received tamoxifen and ovarian suppression had worse menopausal symptoms and other symptoms early on. Women in this group:

  • Were significantly more affected by hot flashes and sweats at 6 months and 24 months. There were no differences between the groups by 60 months.
  • Showed a significantly greater loss of sexual interest at 6 months, but not at 24 months or later. They had more difficulty becoming aroused at 6 months and 24 months.
  • Had more trouble sleeping at 6 months but not later.
  • Were more likely to report vaginal dryness throughout the study. Those on tamoxifen alone had more vaginal discharge and itching at the early and middle reports.

Changes in areas such as physical well-being and mood, which are used to measure quality of life, were small and similar between the groups.

Women who had been treated with chemotherapy before the study had worse symptoms at the study’s start. Getting earlier chemotherapy did not make those women’s symptoms worse for the length of the study, results that went against what researchers had expected. Some symptoms and quality-of-life measures were even less notable during the study period in those who had chemotherapy. The researchers noted that this group also benefits most from ovarian suppression.

Results for women given exemestane plus ovarian suppression were not formally compared to the other two groups, but showed more problems with sexual function, vaginal dryness, and bone and joint pain.


What this means for you

When your primary treatment for breast cancer ends, you may feel relieved. You might also be worried about what comes next. If you are still premenopausal and have hormone receptor-positive disease, your doctor might suggest ovarian suppression plus hormonal therapy. This can lower the amount of estrogen in your body. Yet the possibility of side effects may concern you.

Tamoxifen, exemestane, and ovarian suppression each can cause menopausal symptoms on their own. The addition of ovarian suppression to tamoxifen or exemestane increases these.

In this analysis, women reported their experiences while on hormonal therapy and ovarian suppression. Like symptoms of natural menopause, the symptoms caused by treatment lessened over time.

Talk with your healthcare team about the treatments you are considering or are receiving to weigh the benefits against possible difficulties. Ask your oncology nurse or other provider about ways to manage specific symptoms. Volunteers on our Breast Cancer Helpline also can suggest approaches that may help.

Ribi, K, Luo, W, Berhhard, J, et al. Adjuvant Tamoxifen Plus Ovarian Function Suppression Versus Tamoxifen Alone in Premenopausal Women With Early Breast Cancer: Patient-Reported Outcomes in the Suppression of Ovarian Function Trial. Journal of Clinical Oncology. Published ahead of print in March 2016. DOI: 10.1200/JCO.2015.64.8675.


This article was supported by the Grant or Cooperative Agreement Number 1 U58 DP005403, funded by the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention or the Department of Health and Human Services.


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