HABITS trial

2 April 2008


This trial evaluated the safety of a short course of hormone replacement therapy in women with previously diagnosed early breast cancer who suffered from bothersome menopausal symptoms such as hot flushes and night sweats.

Scientific Title: IBCSG 17-98/BIG 3-97

HABITS – A randomised clinical trial concerning hormonal replacement therapy (HRT) after previous radical breast cancer treatment.

Short title: Hormone replacement therapy After Breast cancer is IT Safe?


There are now more breast cancer survivors with menopausal symptoms due to increased incidence of breast cancer and improved survival times after treatment. Second, many cancer treatments (e.g. chemotherapy) cause early menopause and symptoms that are difficult to manage by non-hormonal means.

Hormone replacement therapy (HT) is known to increase the risk of breast cancer in healthy women, but its effect on breast cancer risk in breast cancer survivors is less clear. It is possible that the mechanism whereby hormone replacement therapy (HRT) induces and promotes tumor growth in healthy women may be different from its ability to promote the growth of micro-deposits of tumor cells in breast cancer survivors. Prior observational studies and analyses of clinical case series whose results seemed reassuring in general in that they found no increased risk of breast cancer recurrence following HRT


The HABITS trial was stopped early due to suspicions of an increased risk of new breast cancer events following HRT. These results raise a challenge for researchers of finding non hormonal relief for bothersome menopausal symptoms in breast cancer survivors.

Main publication

Increased risk of recurrence after hormone replacement therapy in breast cancer survivors. Holmberg L, Iversen O-E, Rudenstam CM, Hammar M, Kumpulainen E, Jaskiewicz J, Jassem J, Dobaczewska D, Fjosne HE, Peralta O, Arriagada R, Holmqvist M, Maenpa J.  J Natl Cancer Inst 2008; 100:475-482.