The risk of developing breast cancer really needs some context to make sense and this table illustrates the relative risks of various factors that can result in developing breast cancer.
Conventional HRT comprises oestrogen and progestogen (which is a progesterone like substance but not actually the same as the progesterone we make ourselves) The progestogen is given to protect the lining of the womb from developing womb cancer – so taking oestrogen alone is not recommended if the woman still has a womb. This risk does not apply if using natural progesterone (for example if the HRT formulation is Bio-identical HRT- which means the hormones are identical to those produced naturally by our body) The Lancet study and the NICE guidelines are looking at progestogen and not progesterone.
So even if the risk of breast cancer attributable to taking conventional HRT was deemed to be double what had previously been thought, ( an extra 4 people in 1000) as published in the Lancet, it can readily be understood that this is not a huge increase when it is so possible to influence other confounding factors like exercise, alcohol, smoking and being overweight.
In fact if one wanted to positively influence the risk of getting breast cancer then not being overweight, not smoking nor drinking excess alcohol combined with taking oestrogen only HRT combined with Bio-identical progesterone and exercising regularly could lower the risk to 12 women in 1000 - which is surely worth considering.