Oncology (General Cancer)/false negatiave on bone scan
I have breast cancer and just had a bone scan. I had a PET/CT that had lots of diffuse sclerosis--so if it were cancer it would be blastic cancer.
But, my doctor thinks it is probably not cancer since in his 30 years of practice he has never seen metastasis be so diffuse and symmetrical (and extensive).
WE did a bone scan and it came out negative. Now I am wondering if just finishing AC chemo (11 days ago) could make the bone scan a false negative.
Here is my thinking: bone scans show where bone is being built up or torn down. After undergoing chemo, that is probably all quieted down--no bone building (or breaking down). So the bone scan would be negative.
Is this possible?
You are right. This phenomenon has been known for a long time in patients with prostate cancer metastatic to bone, who get castrated; the disease abruptly stops, and if you take the bone scan at the right time, you would have a false negative. Blastic cancer is rare in breast cancer, but not unheard of, and this is one of the explanations for a positive PET/CT and a negative bone scan after chemotherapy. Another might be a different sort of bone disease such as sarcoidosis.
If you were my patient I would want to know if the alkaline phosphatase was elevated when you had the positive PET; usually that's a pretty good marker for bony disease, although it isn't specific.
Finally, whether or not you had blastic breast cancer in your bones, it might be a good idea to discuss the use of zoledronic acid, given that we have some clinical evidence that patients who take this tend to have an increased time to recurrence in the bones, and maybe there is an antitumor effect with respect to disease that is in bone. Hope this helps.