Ca 15-3 and Femara

After two years of taking Nolvadex, I was switched to Femara, and taking it for 6 months already. Last 15 months, my Ca 15-3 are incrissing, at the moment the value is 344,7. During wholl that time the alcaline phosphatase was of the normal values. I have a sanated rib fractuer. My hormoun status is varying between menopausal and postmenopausal. It wasn't practicated the ovarian castration to me. All the other results are good. I am worried. Is there some probability that it is not metastatic bone? Thank you in advance

[Cleveland Clinic]

Dear Ekaterina:  The CA15-3 is a non-specific tumor marker.  It is most commonly used to help doctors know if treatment is going in the right direction.  It usually is not used alone and should be correlated with the other tests and information to help guide treatment decisions.  Please note, femara is only for postmenopausal women.  Without evaluation, we cannot speculate on the cause of the rib fracture.  You should discuss your concerns with your oncologist.