Question normal

I am new to the field and just am trying to find a consistent approach to metastatic disease. Imaging will be concerning for mets/recurrence and sometimes we treat presumptively and other times we re-biopsy. I understand in some cases like breast cancer receptor status can change and thus affect management, also I am sure the likelihood of metastasis to that location also plays a part in the equation for solid/liquid tumors, but I was hoping to get a general approach and reasoning for how to evaluate metastatic or recurrent disease