inhibin marker for GCT

I was diagnosed with granulosa cell tumor of the ovary in March 2003, stage 1a.  My gyn/onc tests my C125 level every 4 months for signs of recurrence. I have read a lot on markers for GCT and see inhibin used most often for a GCT marker. When I mentioned inhibin to my doctor, he said, unfortunately, there are no good markers for GCT.  But why do I see it mentioned most often? And I have rarely seen C125 mentioned as a marker for GCT. So my question is twofold; In order to use the inhibin test, do you have to have an inhibin reading from the time of surgery as a baseline? Also, is C125 a good marker for GCT?