Grapeseed extract

Hi

I am Pam, a 75 year old woman,  diagnosed with stage two breast cancer  caught at a very early stage with an Onc DX score of 6.  I have had a mastectomy and radiotherapy. I was given Exemastane as ì had a bad reaction to the first aromatase inhibitor.  I have had really bad reaction to the Exemastane and have heard that grapeseed extract can work to lower oestrogen levels. 

Has anyone got any experience of this natural alternative.