Triple +ve breast cancer - bone mets concern?

Mummysgal

Hi! This is pretty long - so thanks in advance for taking the time to read it.

My mother was diagnosed with stage 1, grade 1, triple positive breast cancer approx. 16 months ago (@44). She had a full mastectomy, was given Tamoxifen and only chemotherapy: Herceptin every 3 weeks for 52 weeks - about 7 cycles left. About 3 months ago, she developed pain in her back. We had a blood test done right away and it came back negative. Then the pain increased and after a month, had an X-ray and CT scan done which showed a tumour in her L3 vertebrae (lightly touching the L2 as well). We had a needle biopsy done last month which again came back negative.

Now she is in severe pain - can't even get out of bed..Our oncologist is going to give her radiation on Monday (in 2 days). Could it have been a false negative? Could it be cancer? I'm so worried. Please can you share your experience/thoughts? Thanks.