Low CA-125 and ovarian cancer?

My best friend was recently having some bowel symptoms, and went to her doctor who palpated an adenexal mass.  A CT was obtained, as well as a CA-125.  Her result was 9, so we were fairly elated, thinking it was perhaps a dermoid or something else benign.  She had an exploratory, and we were all stunned when the path came back as ovarian CA.  However, her doctor seems to think it is very early, no metastatic disease has been noted.  

Why would the CA-125 have been so low?
I know you can't say for sure, but wouldn't chemo still be recommended?  Not sure what stage she is, but the doc said "extremely early".

Thank you so much.

[nurse12hr]

Thank you so much for clearing this up for me.  I don't know if my friend has the final path back.  I do know that the surgery was very complicated due to her previous bowel surgeries.  The doc said she would not be able to have a second look surgery.

thanks again.