Breast cancer HRT risk lower than thought

A woman’s risk of developing breast cancer while taking hormone replacement therapy (HRT) might be lower than previously thought, according to new research.

In a study published in the British Medical Journal, researchers from the New South Wales Breast Cancer Institute estimated a woman’s individual risk of breast cancer up to the age of 79, in relation to HRT, using the latest data.

Researchers found that the cumulative absolute risk of breast cancer fell with increasing age in women who did not take HRT. The team said that the average baseline risk (from 40 – 79) is around 7.2% (1 in 14), which fell to 6.1% (1 in 16) at 50 years and 4.4% (1 in 23) at 60 years.

The team said that the use of HRT only resulted in a slight increase in a woman’s cumulative risk. The study found that the use of oestrogen only hormone replacement or short-term (around five years) use of combined therapy (using both progesterone and oestrogen); beginning at age 50 hardly affects the cumulative risk.

However, the use of combined therapy for around 10 years, was found to increase the cumulative risk to 7.7%, while researchers found that long-term use of oestrogen-only treatments had a “minimal effect” on breast cancer risk.

The study concluded that additional breast cancer risk is greater with combined therapy, especially if it was taken for over five years. However, once HRT is stopped, researchers say, a woman’s breast cancer risk returns to that of a non-user of the same age.

Commenting on the findings of the study, Professor John Boyages, Director of the New South Wales Breast Cancer Institute, said: “Although we found the additional breast cancer risk with hormone replacement therapy for an individual is very small, the effect on the general incidence of breast cancer would be greater, especially in populations with high levels of use.

“The reasons for taking hormone replacement therapy vary and decisions about its use must be made at an individual level. Our analysis provides women and clinicians with better information to make these choices.”

(KMcA/SP)