Even short-term HRT harmful for women with previous breast cancer

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Rheumawire

Feb 3, 2004

Even short-term HRT harmful for women with previous breast cancer

Uppsala, Sweden - Even short-term use of hormone replacement therapy

(HRT) poses an unacceptably high risk of breast-cancer recurrence in

women who have previously had the disease, a new study shows [1].

The Swedish study will appear in the February 7, 2004 issue of the

Lancet, but the results were made available online yesterday. The study

was stopped early because of an " unacceptably high " rate of

breast-cancer recurrence in the HRT group.

The authors, led by Dr Lars Holmberg (University Hospital Uppsala,

Sweden) note that the increasing survival of women with breast cancer

has made the management of menopause an important clinical issue. The

Hormonal Replacement Therapy after Breast Cancer Diagnosis Is it Safe?

(HABITS) trial was 1 of several established during the 1990s to assess

the possible risk of recurrent breast cancer for women using HRT.

The HABITS trial was originally planned to include at least 1300 women

with previous breast cancer randomized to HRT for 2 years to treat

menopausal symptoms or to no HRT. The trial was not blinded, and the

choice of specific type of HRT was directed by the local practice. The

trial was stopped on December 17, 2003, after an average follow-up of

just over 2 years. Data were available on 345 women who had had at least

1 follow-up assessment. Recurrence of breast cancer occurred in 26 women

in the HRT group, compared with 7 women who did not receive HRT

(relative hazard 3.5, 95% CI 1.5-8.1). Serious adverse events were also

increased in the HRT group (8 vs 4).

Due to slow recruitment, in 2002 it was agreed that the HABITS trial

would be pooled with a similar trial in Stockholm, Sweden, for analyses

of the results. The agreement stipulated that the data monitoring

committees should discuss the findings with the steering committees when

the relative hazard from the 2 trials combined was statistically

significantly larger than 1.00. This result was reached in the recent

third safety analysis (relative hazard=1.8, 95% CI 1.03-3.1). However,

the 2 trials showed different results when considered separately, with

the Stockholm trial not showing an increased risk of breast-cancer

recurrence on HRT (relative hazard 0.82 (95% CI 0.35-1.9). The

researchers say that the reason for this difference is unclear.

Nevertheless both trials were stopped.

They add, however, that the women in the trials will be followed up for

at least 5 years after randomization and the steering committees will

continue to collaborate with other studies in the same clinical domain.

In an accompanying commentary [2], Dr Rowan T Chlebowski (Harbor-UCLA

Research and Education Institute, Torrance, CA) and Nananda Col (Brigham

and Women's Health Hospital, Boston, MA) note: " Although the HABITS

trial may arguably not be the definitive word on the use of hormone

therapy in women with breast cancer, it will probably be the last word. "

They point out that the results of HABITS are consistent with findings

from the Women's Health Initiative and the observational Million Women

Study, both of which showed an increased risk of breast cancer with

hormone therapy, adding that " such findings are most consistent with

direct effects of hormone therapy on breast-cancer growth. "

They agree with the HABITS authors that even short-term use of hormone

therapy is now inadvisable in women with a history of breast cancer and

that alternative safe and effective strategies for the difficult problem

of menopausal symptoms in these women need to be developed.

Sue

Sources

1. Holmberg L and H for the HABITS steering and data monitoring

committees. HABITS (Hormonal Replacement Therapy After Breast Cancer--Is

it Safe?), a randomised comparison: Trial stopped. Lancet [453-455].

2004. Available at: http://www.lancet.com.

2. Chlebowski RT and Col N. Menopausal hormone therapy after breast

cancer. Lancet 2004. Available at: http://www.lancet.com.

I'll tell you where to go!

Mayo Clinic in Rochester

http://www.mayoclinic.org/rochester

s Hopkins Medicine

http://www.hopkinsmedicine.org