Is there a method to assess tumour cell instability on formalin-fixed paraffin-embedded samples?

Malignant tumours can metastasise and kill the patient. There are well documented prognostic parameters in most tumours, which serve as a surrogate for assessing biological behaviour. However, some tumours do not behave as expected. It is possible that some malignancies are so genetically unstable that they effectively self-destruct rather than continue to grow and spread. It is this that I wish to investigate in a series of tumours.