Claire, a PET scan is a very sophisticated way to search for cancer cells. Most likely the doctor is trying to see if the cancer has spread to your lymph nodes, as this may guide him in the type of chemotherapy you get. Or he may be trying to see if there are any other areas in your breast that need to be looked at. Either way, he's no doubt recommended the procedure for a good reason - I'm sure he's going to use the info. to finalize your treatment plan. Patience - and good luck. PJH