As far as I know there are no studies showing that Starflower oil can eliminate hot flushes, but it is a dietary supplement which I am sure has good health benefits if your diet is deficient (in gamma linoleic acid I believe)!
Re stopping HRT - lizmc - this subject has been aired many times recently so you will see the discussions along similar lines if you do a search from the Forum Home Page. Unfortunately we on here are all too well aware that despite the recent recommendations (ie from BMS etc as per Sarah2 links below), many doctors (both GPs and specialist gynaes) are either not up to date on the subject, or will not change their stance until the NICE guidelines on menopause are updated.These are currently being reviewed and are due to be published in 2015.
In the meantime - yes we do have to take the matter in our own hands and with the help of sites and forums like this one, can become well informed so that we can tell the doctors what we want to do and why, while accepting what risks there might be.
In terms of delaying the menopause, this is partially true, in that for some women the body seems to react to sudden (or even gradual) drop in oestrogen (from stopping HRT) - and gives us back those dreadful hot flushes and sweats we got rid of years ago! However what you won't get later on is the turmoil associated with the fluctuations in hormones that causes some of the other symptoms ie mood swings etc - because the hormones just stabilise - but at a low level. Unfortunately this can also lead to permanent low mood and/or anxiety in some women. It is a complex area and as already said you won't know how you will react , or how you would have reacted had you not taken HRT and I strongly agree that quality of life, as well as general health benefits (from HRT) are especially important considerations.
You don't say what HRT type you are taking but you mention safety - and as you get older - heading towards 60, the safest types are transdermal (patch or gel) oestrogen as oestradiol, and "natural" progesterone - ie the one that is the same as that produced in our own body. At this point there is no need to worry about this though - just to bear in mind for the future.
Hurdity x