which test do I need?

I have had a 6 week history of "sit bone" pain on the left (ischial tuberosity) . It started after I lifted a very heavy piece of furniture with extreme back pain for 2 days.  That cleared up, but the "sit bone pain" continues. After a month, I went to my gp who ordered an l/s spine MRI which was normal.  I asked about a pelvic MRI, but he said that wasn't necessary. The pain continues.  Should I see my oncologist and ask about a bone scan, or what other test do I need?  I was diagnosed stage 3, 5 years ago and have been cancer free after treatment, but I am worried about bone mets and wonder how often does bone cancer metastasize to the ischial tuberosity? Thank you.

[Fernando Roque, MD]

Hi.  The persistent pain in the area of your lower back and buttocks should be investigated for the possibility of metastatic bone disease, given your previous history of Stage 3 breast cancer.  I think you should see your oncologist and ask for a bone scan.  It's better to be cautious and do the scan early.  Even if the results are negative, at least this puts your mind at ease.