Yes, when a family member was fighting metastatic pancreatic cancer, their doctor had a tumor biopsied and sequenced to see if they could try one of the new immunotherapies. Sadly no, and I learned that only a small percentage of hard cancers are yet treatable that way (which still helps a significant total number of people though).
Well, there are two broadly different ways in which sequencing can help.
1. "Targeted therapies" that directly target unique surface features that specific mutations create. E.g. BRAF
2. Sorting most effective treatment by cancer type, where cancers driven by different mutations in different types of cells respond to specific treatments better or worse. Especially important for metastatic where you may have a pancreatic cancer mutation tumor in your lungs, etc.
