Drbellevue, I think your GP is not only out of date but also very wrong. Unless you have a family history of breast cancer, there is no evidence to suggest that the newer, bio identical, transdermal forms of HRT increase the risk of breast cancer, in fact, some experts now think it can decrease it so the complete opposite of what your GP said. All the previous guidelines, like the time limit of only taking it for 5 years, were completely wrong and have since been discredited along with the two very dubious studies.
I have heard that oral forms of HRT have a slightly higher risk of causing stroke/heart issues but even that is pretty inconclusive.
Any small risk of breast cancer is in the dreaded synthetic progestin component of HRT, not the oestrogen part. I intend to take HRT for life and I hope you are not put off by this and carry on taking it if you are happy with it. What your GP needs to realise is that once you stop taking oestrogen, a whole host of other health nasties start to surface.