What do I say to my Dr. who thinks all HRT is the same?

Fundamental differences exist between synthetic hormone-like drugs (conjugated equine oestrogens and medroxyprogesterone acetate) that are not identical in structure to the body's own hormones, and bioidentical hormones (17beta oestradiol and natural progesterone) that are identical in structure to the body's own hormones. Bioidentical hormones are precise duplicates of the hormones produced by the human body. Why does this matter? Well the E3N cohort study which looked at over 80,000 post menopausal French women and found that those taking bioidentical oestrogen and bioidentical progesterone had NO increased risk of breast cancer, but that those taking oestrogen combined with a synthetic progestagen had a 1.69 x increased risk of breast cancer. Synthetic progestogens, in addition to binding to the progesterone receptor, also bind to the glucocorticoid, mineralocorticoid and androgen receptors.[1] This binding can lead to unwanted side effects such as unfavourable glucose metabolism, fluid retention, acne and weight gain. In the central nervous system, synthetic progestogens tend to cause anxiety and irritability whereas bioidentical progesterone is calming. [2] It is likely that these differences also contributed to the adverse outcomes in WHI, which were contrary to the cardiovascular benefits seen in previous observational trials.[3]

Hormones have so many benefits and hormones prevent us against the diseases of ageing such as cardiovascular disease, osteoporosis and dementia.

The latest British Menopause Society guidelines and the new NICE guidelines in 2015 state:

For most women the benefits outweigh the risks when HRT is started at the time of menopause
‍There’s no arbitrary maximum duration of therapy
Doses should be individualized

and in the words of a BMS researcher: "It is imperative that in our ageing population research and development of increasingly sophisticated hormonal preparations should continue to maximise benefits and minimise side effects and risks." [4]

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Here are some interesting papers that highlight some differences between different types of hormone replacement therapy.

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A study of 54,548 women found that synthetic progestins increased the risk of breast cancer whereas women who took bioidentical progesterone had no increased risk. [5]
Fournier et al looked at the incidence of breast cancer in more than 80 000 postmenopausal women and found that If a synthetic progestin was used in combination with oestrogen, the risk for breast cancer increased, whereas for women who used bioidentical progesterone the risk was actually decreased.[6]
A case-control study in France found that synthetic progestin use increased the risk of breast cancer whereas bioidentical progesterone didn’t [7] (in fact the risk was slightly decreased in the bioidentical progesterone group).
The Women’s Health Initiative showed that women on hormones containing synthetic progestin had an increased risk of breast cancer but those on oestrogen only didn’t.

[1] Pharmacological profile of progestins;

[2]Progestogen intolerance and compliance with hormone replacement therapy in menopausal women

[3] Body identical hormone replacement;

[4] It is imperative that in our ageing population research and development of increasingly sophisticated hormonal preparations should continue to maximize benefits and minimise side effects and risks

[5] Breast cancer risk in relation to different types of hormone replacement therapy in the E3N-EPIC cohort

[6] Unequal risks for breast cancer associated with different hormone replacement therapies

[7] Risk of Breast Cancer by Type of Menopausal Hormone Therapy: a Case-Control Study among Post-Menopausal Women in France