My question is around the duration for which I need to take Anastrozole. It was suggested that I should take it for 5 years but I don't know if this is minimum length of time or a maximum?  

I have the BRCA2 mutation, and choose to have a bilateral oopherectomy in my early 50s to reduce my ovarian cancer risk.

I was on HRT for 5 years following the surgery but was advised that taking it for longer increased my risk of breast cancer.  Two years ago, aged 58, I started on Anastrozole as this was recommended to help reduce my breast cancer risk.

I am finding that I am suffering from frequent hot flushes particularly at night which are disrupting my sleep.  I did have very frequent flushes immediately after my operation, and before I started taking HRT but I had wondered if the continuation of the night time flushes was likely due to the effects of Anastrozole.  

Can I temporarily stop the Anastrozole to see if it improves the symptoms without negating its preventative effects? And if so how long do I need to wait for any change to show up.

Also if I decide to stop taking it before 5 years will the 2+ years I have been taking it for have any benefit?