HRT trial stopped early after 'unacceptable risks' for women with previous breast cancer


NB: Please note that if you are outside North America, the embargo for LANCET press material is 0001 hours UK Time Tuesday 3 February 2004

A Swedish study established to assess the effect of hormone replacement therapy (HRT) for women with a history of breast cancer has been stopped early after preliminary results show 'unacceptably high' risks of breast cancer recurrence for HRT users. The results are published online by THE LANCET (3 February 2004) and will appear in the February 7 print edition.

The increasing survival of women with breast cancer has made the management of menopause (either natural or early-onset due to hormone therapy or chemotherapy) an important clinical issue. The HABITS trial (Hormonal replacement therapy after breast cancer diagnosis-is it safe?) was one of several trials established in the 1990s to assess the possible risk of recurrent breast cancer for women using HRT. Originally planned to include at least 1300 women followed up for five years, the trial was stopped on December 17, 2003, after an average follow-up of just over two years. The steering committee for the trial were concerned that early results from the study showed an unacceptably high risk of recurrent breast cancer for those women randomised to receive HRT; of 345 women (all of whom had had previous breast cancer and were randomised to HRT or no HRT) with at least one follow-up assessment, 26 in the study arm allocated HRT reported a recurrence (or a new case) of breast cancer, compared with seven women who received therapy other than HRT for menopausal symptoms.

Lead investigator Lars Holmberg from University Hospital Uppsala, Sweden, comments: "The HABITS trial was terminated because women with a history of breast cancer allocated to receive HRT for menopausal symptoms experienced an unacceptably high risk of breast cancer compared with breast-cancer survivors allocated to best symptomatic treatment without hormones. Women on active treatment have been advised to discontinue. However, the women in the trial will be followed up for many years and the steering committee of the HABITS trial will continue to collaborate with other ongoing studies in the same clinical domain."

In an accompanying Commentary, Rowan T Chlebowski (Harbor-UCLA Research and Education Institute, USA) and Nananda Col (Brigham and Women's Health Hospital, Boston, USA) conclude: "…considering all available evidence about the effect of hormone therapy on breast cancer and chronic disease, the HABITS investigators' conclusion that even short-term use of hormone therapy poses an unacceptably high risk of breast cancer can now reasonably guide clinical practice for women with breast cancer…Alternative safe and effective strategies for the difficult problem of menopausal symptoms in these women now need to be developed".

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