What Is The Treatment For Breast Cancer And Costochondritis?

I am currently in treatment for breast cancer (Aredia every 8 weeks and I also take tamoxifen). My CEA levels have been going up and down all year long. Last PET scan in January showed no evidence of progression of the cancer. Six weeks ago I was diagnosed with costochondritis. Since it has only subsided a little bit and my CEA level is elevated once again, is it possible that the costochondritis could cause the CEA to go up? I am scheduled for a PET scan later in the month. Also, my other lab tests have remained with normal limits during all this time (Alk phos, ALT, calcium, blood counts, Beta microglobulin, creatinine).