In their article, Associate Professor John Eden, Associate Professor of Reproductive Endocrinology at the University of NSW, and his co-authors, report a world first: three cases where women taking compound hormone replacement therapy, or "bioidentical" HRT, developed endometrial cancer.
Pharmaceutical HRT is an established and tested therapy for the relief of menopausal symptoms, and is regulated by the Therapeutic Goods Administration (TGA), Assoc Prof Eden says.
In this form of therapy, the risk of developing cancer from unopposed levels of oestrogen is reduced by the inclusion of progestin, a synthetic hormone similar to progesterone.
Bioidentical HRT, "hand made" by compounding chemists, is not directly regulated by the TGA and little is known about quality control measures to ensure balanced doses of oestrogen and progesterone.
Assoc Prof Eden suggests the cases of the three women, two who were menopausal and one who was menstruating, raise the possibility that bioidentical HRT increases the risk of developing endometrial cancer as a result of high levels of oestrogen.
"It should be noted that the Australasian Menopause Society does not recommend the use of bioidentical HRT," Assoc Prof Eden says.
"Until this therapy has been properly tested, it may be prudent not to advocate bioidentical HRT, and to perform annual ultrasounds and biopsies on women who continue to use this therapy."
The Medical Journal of Australia is a publication of the Australian Medical Association.