Prognostic factor research in oncology.

The prognosis of solid tumors is predominantly influenced by the anatomic extent before and after initial treatment. It is defined by the TNM/pTNM system and the residual tumor (R) classification as internationally agreed on and published by the International Union Against Cancer (UICC). However, there are several independent factors effective in prognosis in addition to TNM and R. Their identification is the first objective in prognostic factor research. Correctly applied multivariate methods appropriate for the specific situation play a key role. Cooperation between clinical oncologists and experienced medical statisticians is indispensable. Putative new prognostic factors have to be carefully evaluated before they can be accepted for general use in clinical oncology. In the future, we have to focus on the development of prognostic systems. Such systems integrate multiple independent prognostic factors with present staging (TNM, R) to improve the assessment of prognosis.