CA125 fluctuation

i was diagnosed with ovarian cancer- CA125 aws 200, initial responses to taxol/carbo gave a total response immediately(after the first 3 infusions) and i had 6 large combo infusions. my CA125 dropped to 20, subsequently the ovaries were removed revealing microsopic residual and i am on 12 maintanence doses weekly of taxol. my CA125 dropped to 10 after the first 3. after the first 6 it was 12.3 - what kind of increase in CA125 would be be an indication that the disease has progressed. or will the CA125 naturally fluctuate within a range and not be a factor at all.