HRT after a diagnosis of breast cancer – cancer recurrence and mortality

The following is an abstract of a research article written by Eva M Durna, Barry G Wren, Gillian Z Heller, Leo R Leader, Peter Sjoblom and John A Eden published in the Australian Medical Journal. In Australia, approximately 11,000 women are diagnosed with breast cancer each year. About three-quarters are over the age of 50, and many have menopausal symptoms. In addition, most chemotherapies for breast cancer can cause ovarian dysfunction or premature menopause, and 60% of premenopausal women who receive adjuvant therapy for breast cancer subsequently have oestrogen deficiency. A significant reduction in menopausal symptoms and improvement in bone mineral density have been reported in women taking HRT after breast cancer diagnosis. However, few women use HRT after treatment for this disease, possibly because of concern about the effect on disease progression. Nevertheless, none of the previous studies of breast cancer survivors prescribed HRT have found an increased risk of tumour recurrence or death from progressive disease.

Objective

To determine whether hormone replacement therapy (HRT) after treatment for breast cancer is associated with increased risk of recurrence and mortality.

Design

Retrospective observational study.

Participants and setting

Postmenopausal women diagnosed with breast cancer and treated by five Sydney doctors between 1964 and 1999.

Outcome measures

Times from diagnosis to cancer recurrence or new breast cancer, to death from all causes and to death from primary tumour were compared between women who used HRT for menopausal symptoms after diagnosis and those who did not. Relative risks (RRs) were determined from Cox regression analyses, adjusted for patient and tumour characteristics.

Results

1122 women were followed up for 0-36 years (median, 6.08 years); 154 were lost to follow-up. 286 women used HRT for menopausal symptoms for up to 26 years (median, 1.75 years). Compared with non-users, HRT users had reduced risk of cancer recurrence (adjusted relative risk [RR], 0.62; 95% CI, 0.43-0.87), all-cause mortality (RR, 0.34; 95% CI, 0.19-0.59) and death from primary tumour (RR, 0.40; 95% CI, 0.22-0.72). Continuous combined HRT was associated with a reduced risk of death from primary tumour (RR, 0.32; 95% CI, 0.12-0.88) and all-cause mortality (RR, 0.27; 95% CI, 0.10-0.73).

Conclusion

HRT use for menopausal symptoms by women treated for primary invasive breast cancer is not associated with an increased risk of breast cancer recurrence or shortened life expectancy.

(Source: eMJA)