Although there is no clear explanation for the divergences registered between studies, it could be speculated that differences in blood sampling schedule, sensitivity of hormone assays and formulation of hormonal products, may be responsible for the discrepancy.
(For example: pills with lower doses or different formulations of hormones).
Many questions remain and it is possible that future studies will find that benefits outweigh risks, perhaps with different combinations or formulations of hormones.
MicroChips' scientists developed a freeze-dried formulation of the hormone that is packaged in the device and released on command, eliminating the need for injections.
The risks of ovarian cancer were about the same from hormone therapy regardless of the duration of use, the formulation of the hormones, the estrogen dose or how it was administered, according to the study.
"If it doesn't improve after three to six months, then it might mean that she needs a change in formulation of the hormones or an alternate form of contraception".
Other influencing factors include study setting, selection of confounding factors, small sample sizes, limited age range of participants, formulation of exogenous hormones, and duration of the application.
Twelve premenopausal patients with advanced breast cancer were randomised to receive 3.75 or 7.5 mg of a slow release formulation of the luteinising hormone releasing hormone agonist leuprorelin once every 4 weeks.
Proliferation of the endometrium is a normal part of the menstrual cycle, but factors that increase oestrogen exposure without compensating progesterone, such as oestrogen-only formulations of menopausal hormone replacement therapy, can increase endometrial cancer risk (Weiderpass et al, 1999).
When I was a medical reviewer at the FDA in the 1980s, a completely unexpected side effect occurred in the clinical testing of a new formulation of human growth hormone synthesized in bacteria.
