Reccurence of brst cancer. Than zometa?

- Breast cancer recurred after 3 years of its diagnostic. - done with PET CT - findings are only bone mets, no other organ is affected. - cancer type is metastatis triple negative breast cancer, which is diagnosed in 2014. - doctor advised me to do bone biopsy as he said 33% of patients' hormones get changed. - if harmones changed then we give her hormone therapy. - also we are giving x-geva so that we can reduce her pain. My questions: 1. Is bone biopsy fine? Or it could have complications? Should I go for bone biopsy as it is the only chance to see if receptors get changed or not? 2. Is X-Geva is better than Zometa, first we have given her Zometa, bit now after 1 month we are giving X-Geva as by doctor suggested, Do Xgeva has more side effects than Zometa? Thanks.