The prognostic assessment of cancer patients is of special importance clinically and scientifically. Prognostic factors are divided into three groups: patient-, treatment- and tumor-related factors. Only a minority of those factors, for example the UICC TNM classification, have been proven by multivariate studies to be of prognostic significance and have an impact on patient management, even then only as prognostic groups. The individual prognosis of a specific patient, which would allow an individualized therapy, cannot yet be adequately assessed. New prognostic factors may result in improved prognostic predictions; currently it is unclear whether this will be accomplished by molecular prognostic parameters assessed on the basis of the primary tumor or rather by the detection of disseminated cancer cells. Of major importance are well-designed clinical studies, in order to prove the clinical benefit of an individualized patient management.