Metastasic Bone CA

My wife has Breast Cancer metastasized to the bone.  Recent scans indicate new lesions and activity in previous lesions. This is consistent with an increase in CA 27.29 from 150+/- to 320+/-.  Beyond the obvious, shat does CA 27.29 in the range of 320 indicate? And when is CA 27.29 too high?

[CCF-RN,MSN-JS]

Dear GEMC, CA27.29 is a nonspecific marker for breast cancer.
The use of CA27.29 to detect breast cancer recurrence at present is controversial.  However, in your wife's case the increase in CA27.29 is happening and new lesions are found in the bone. The fact that new lesions are found is more important than what the level of CA27.29 is. Treatment decisions will be based on the fact that new disease is found, and not on whether the CA27.29 is at a certain level.