How bad is diagnosis of invasive ductal carcinoma high grade?

Depends. Not all breast cancers are the same and many other factors help to predict better or poorer outcomes such as tumor grade, # of positive lymph nodes, estrogen receptor status, her2neu status, etc. A score called oncotype DX based on genetic profiling of the cancer helps define prognosis also and tailor decisions as to the best and most beneficial treatment to use.