Yin tonics and Oestrogen-sensitive cancer

Well there are no strong clinical studies indicating any risk from kidney tonic herbs - certainly to the degree that we can see with HRT. While the kidney tonic herbs can alter hormone levels it is more the body doing it and done more systemically, than simply providing hormones which has far more risk. That said, the answer is largely that we do not know the answer in pure clinically based and/or biochemical terms.

My personal opinion is that when the diagnosis is correct, there is very low potential for any potential problems.

One study looking at the formulas liu wei di huang wan Effects of the Chinese Herbal Formulation (Liu Wei Di Huang Wan) on the Pharmacokinetics of Isoflavones in Postmenopausal Women had this to say “Hormone therapy (HT) diminishes vasomotor symptoms in a dose-dependent fashion. However, the use of estrogen alone in HT increases the risk of endometrial hyperplasia and cancer, while continuous use of combined HT (estrogen plus progestin) may increase the risk of coronary heart disease, breast cancer, stroke, and venous thrombosis [3–5]. Concern over the potential adverse effects of HT leads many women to look for natural alternatives that would provide benefits comparable to those of estrogen but without serious complications. Soy isoflavones, known as phytoestrogens, have been shown to reduce vasomotor symptoms significantly without an adverse effect on the endometrium or vagina [6, 7]. In addition, they are considered beneficial for reducing the incidence of cardiovascular disease, hormone-dependent breast cancer, colon cancer, and osteoporosis [8–11]. Likewise, Traditional Chinese Medicine (TCM) is one attractive option for alleviating menopausal symptoms. According to TCM, vasomotor symptoms (especially hot flushes and night sweats) are caused by Kidney Yin Deficiency. The Chinese herbal formulation of choice for nourishing Kidney Yin Deficiency is “Liu Wei Di Huang Wan” (LWDHW) or “Six-Ingredient Pill with Rehmannia.” This formulation consists of Shu Di Huang (Radix Rehmanniae Preparata), Shan Zhu Yu (Fructus Corni), Shan Yao (Rhizoma Dioscoreae), Ze Xie (Rhizoma Alismatis), Mu Dan Pi (Cortex Moutan), and Fu Ling (Poria). A modified formulation of LWDHW has been shown to be significantly effective in reducing the number of hot flushes without serious adverse reactions [12, 13]. LWDHW, in addition to being a popular Chinese herbal formula used in the treatment of vasomotor symptoms, is also used in the treatment of other medical conditions such as diabetes [14], hypertension [15], and disorders of the immune system [16].”.

The study gets into more biochemical details of what I was saying above in that there appears to be a large difference in cancer relationships between giving a hormone and using a balanced formula or substances that systematically can alter the bodies levels of certain hormones. Even if one or a few of the ingredients has the potential to raise estrogen levels in some cases.

There is a fairly lengthy article from Dr. Dharmananda entitled ESTROGEN DEPENDENT TUMORS AND HERBS:
How Modern Conditions Change Traditional Practices. One study he references in that article the authors concluded that " in a 1998 publication showing that kidney tonic herbs (mainly rehmannia, epimedium, dioscorea, cuscuta, cornus) could raise estrogen levels substantially during menopause and even 10 years after menopause, the authors wrote: “The results indicated that the hormonal disorders in post-menopausal females could be corrected by kidney tonic herbs by way of raising the levels of estrogen and calcitonin, and reducing the levels of parathyroid hormone.” The authors took the view that the problem with hormone replacement therapy was the use of a single hormone which can present side effects, where as “kidney tonic herbs mobilize all positive factors through general regulation.” Which is basically saying the same thing.

So I wouldn’t unnecessarily put a patient on formulas in that class without a good reason, nor would I leave them on for long periods of time, but all things considered I feel there is far more clinical value in resolving the kidney yin deficiency and the problems that can cause with stress relationships to cancer and other by products of that diagnosis than there is risk with the hormone altering potential of the formulas.