Mom has stg 4 ovarian cancer with recurrence. Is now on avastin (bevacizumab). She feels good, ascetis has gone down, however ca125 has gone from 211 to 3000. Why?

Good question. Why? It is definitely something her oncologist should be concerned about and should try to answer the question. Your mom should get some evaluation done-i.e. Some imaging studies- like ct and or pet scan to answer the question and to see whether Avastin (bevacizumab) alone perhaps is not enough.