Anyone had Ablation done (liver) while on Folfox?

In February, my dad had ablation done to zap one spot on his liver (very small). At the time his CEA was 2.8. It had decreased during the previous months while he was on treatment. In April his CEA climbed to about a 6/7. He had a PET scan and it was negative. All it showed was the healing in his liver from the ablation. In June, CEA climbed to 9. He is scheduled for another PET scan at the end of July. Has this happened to anyone else?

Thanks,
Jennifer