A connection between breast cancer and bone cancer

Also, if you had pure DCIS, it is incapable of metastasizing to the bone, so for that to happen you either would have had to have had an undetected new primary or an undetected invasive recurrence, both of which are VERY unlikely.   There are many things that could be wrong other than cancer, although I understand why your mind goes there.   Try not to worry until you get a definitive diagnosis.

To answer your question though, I don't know of any connection between breast cancer and primary bone cancer (in other words, cancer than originated in the bone, not the breast).   I would imagine, in that case, that your chances of recovery would depend on details of your new diagnosis, and be independent of your previous breast cancer treatment.   

kca, they are ruling out that you had a missed invasive breast cancer that has now metastasized or an invasive/new invasive cancer that has metastasized.  Like Annette mentioned if you had pure DCIS then metastasis is unlikely.  However,your doctors are just being diligent in making sure that is not what happened.  

You need to see a specialist, a bone physician, as with your increase in alkaline phosphatase  (ALP) it is more likely that what they are seeing is Paget's disease of the bone http://en.wikipedia.org/wiki/Paget's_disease_of_bone (NOT at all related to breast cancer, or Paget's disease of the breast).  I only know about this because I too am being followed for a very large sclerotic lesion, and for the same reason.  For me, Paget's disease of the bone has been ruled out, and I did not have an increase in ALP.    I really hope that yours is simply a bone island.  Good luck.  I know how stressful this can be.