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.
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.