Fulfirinox & Rising CA19

Can anyone tell me if they’ve experienced rises in their CA-19 after Fulfirinox chemo?  A family member diagnosed 1.5 months ago with stage IV with CA-19 of 5,200.  Started Fulfirinox 1.5 weeks after diagnosis – after cycle ONE CA-19 of 6,500, after cycle TWO CA-19 of 9,584.  Oncologist said he doesn’t always rely on these numbers.  Too soon to tell anything and whether or not to switch treatment plans until after a scan.  I did read that these numbers can sometimes increase before they start to decrease???  Any input is appreciated.