[Critical evaluation of the treatment-dependent prognosis index TPI based on the "prospective DOSAK study on squamous cell carcinomas of the lips, oral cavity and oropharynx"].

The "Treatment Dependent Prognostic Index" (TPI), which has been published by the authors in 1982 as a result of a retrospective observational study of the DOSAK (German-Austrian-Swiss Association for Head and Neck Tumors), is submitted to a critical review. For this purpose a sample of 1485 patients representing the "Prospective DOSAK-Study on Squamous Cell Carcinomas of the Lips, the Oral Cavity and the Oropharynx" were classified according to TPI. 13 TPI groups exhibited greater than or equal to 20 patients and were suitable for calculation of observed survival and comparison to their TPI prognoses. In 10 of 13 TPI groups observed and predicted survival are almost identical. 3 TPI groups show a considerable lack of correspondence between observation and prognosis. In general, the analyses revealed a high prognostic validity of TPI in its substantial parts. A further improvement of TPI by taking several tumor sites into consideration seems possible and will be a subject of future investigations.