Withania somnifera extract to counter Estrogen positive breast cancers
Ashwagandha (as Withania somnifera is known in India), is a medicinal herb used since ancient times. It balances hormone levels, tending towards decreasing estrogen levels and increasing testosterone.
Apart from overall health benefits, Ashwagandha also reduces anxiety and counters depression.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3675906/ (Effect of an Extract of Withania somnifera Root on Estrogen Receptor-positive Mammary Carcinomas)
Ashwagandharishta is a famous Withania somnifera Root extract prepared since centuries in India. Available as a standard product on amazon from multiple herbal pharma companies.
While ashwagandharishta is a proper medicine, a milder effect may be obtained from ashwagandha powder (also available online easily), which can be taken mixed with milk.
Withania somnifera is helpful in prevention as well as treatment of almost all cancers (EXCEPT PROSTRATE, where an increased testosterone causes exacerbation). But it deserves special mention for ER+ Breast cancer because of it's estrogen countering effect.
It is also a useful supplement with Chemo.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5271386/ (Withania somnifera Root Extract Enhances Chemotherapy through ‘Priming’)
Here is one link to Ashwagandharishta - https://www.amazon.com/Patanjali-Divya-Ashwagandharista-Asawa-450/dp/B00KRK8HVC/ref=sr_1_1?crid=2C3FBW9KRRU88&keywords=ashwagandharishta&qid=1575052309&sprefix=ashwagandharis%2Caps%2C526&sr=8-1
I searched, but could only find trials on cell lines or mice. Not on real humans.
One possible reason might be commercial - big pharma would want a patentable component which it can produce and earn money from. They would not benefit from trials on herbs.
If you like Ashwagandha, check on it's alcohol extract - Ashwagandharishta. It is significantly more potent: from first hand experience as well as from readings.