Post-axillary dissection steps

I recently had an axillary lymph node dissection and the biopsy results came back with many infected nodes. Doctor said he was able to remove all the lymph nodes and that it doesn't appear that the cancer has spread according to the biopsy. I want to be sure that the cancer has not metastasized beyond the local area but the only way to be sure, I am told, is to go through the next steps: recovery period of six weeks, followed by radiation, then PET scan, and depending on the results, another round of chemotherapy treatment.

Why does the doctor not order a PET scan before my radiation treatment? What if the cancer has spread between now and the time my radiation treatment is over? To me, it makes much more sense to do a PET scan before radiation to get a better understanding of where the cancer is, if any exists after the dissection.

I would like to hear your thoughts. After having gone through chemotherapy and surgery, I am feeling like there is a longer journey to travel ahead...

[Cleveland Clinic]

Dear maytwenty10:  In many centers, PET scan would not be done at all.  The value of PET scan is controversial in breast cancer.  Nonetheless, there is little to no value of doing a PET scan immediately post op as a PET scan measures areas of hypermetabolic activity and in all likelihood a healing surgical site would appear positive and the test would be uninterpretable.  If the plan is to radiate the axilla, the purpose would be to address any remaining axillary disease.  You may wish to direct these questions to your doctor so that he could explain in the context of your situation.