When injected into the body, benzyl alcohol causes precipitation of progesterone and is a powerful neurotoxin, but its harm is reduced by progesterone's anti-toxic action. International research standards have subsequently invalidated research using unsaturated fats as the solvent. However, some researchers, unaware of these findings, have concluded that progesterone causes metastasis in cancer patients. Others do not distinguish between natural progesterone and carcinogenic synthetic progestins. The incidence of breast cancer is high among hypothyroid women and also among women who produce excess prolactin and excess estrogen.
Progesterone has the opposite effect, promoting the release of the hormones from the gland.
At puberty, in pregnancy, and at menopause, the thyroid gland often enlarges, probably as a result of estrogen dominance. Also both oppose the effects of stress, and facilitate nutrition. Since glucose metabolism is disturbed in cancer, it would seem reasonable to combine progesterone therapy with sufficient thyroid to maintain protein assimilation, and to provide a high protein diet to assure that the liver can excrete estrogen. These cases illustrate the anti-tumor effects of progesterone therapy effects of progesterone therapy in patients using natural progesterone. Natural progesterone increased the rate of tumor regression.