Clinical trials provide the best available treatment for patients with a specific disease. In such trials patients will receive treatment according to their individual risk factors. For a disease several risk parameters are known to be predictive for the progression of a disease or for developing complications of treatment. For example in cancer the size of a tumour, the presence of metastases or special molecular genetic findings can be used as such a risk factor. Patients with the same risk factors will be gathered in the same treatment arm in a trial. This is called stratification of the treatment. It helps to increase or decrease treatment intensity according to the individual risk of a patient.
