CA 27.29 elevated, could it be from RA?

2017 I was diagnosed with breast cancer. Had a lumpectomy, 4 months of chemotherapy and 7 weeks of radiation. July 2023 I passed my 5 year mark of being cancer free! Early this month I went to my general practitioner who decided to do a CA 27.29, which I’ve never had before. The results came back at 1844 and I’m completely beside myself. Monday I’m having a mammo and Tuesday a CAT scan of my chest, pelvis and abdomen. To say I’m scared or anxious is an understatement!
Has anyone had CA 27.29 this high? What does it mean? Could inflammation from my RA increase the levels this much or does indicate cancer? Do levels of 1844 get this high from breast cancer or does it mean it has spread? So many questions?? Thanks in advance