Clinical Relevance of Tumor Markers for the Control of Chemotherapy

This presentation is based on our experience with tumor marker monitoring of surgery therapy and chemotherapy effects. The control of chemotherapy is one of the most important problems in oncological practice. The correlation between the clinical status of the patient and tumor size changes, based on the results of different imaging methods, has been the most important and most frequently used method. However, the therapy effect has been recently assessed by markers of the biological activity of the tumor. Using tumor markers for the assessment of the effect of surgery therapy is already part of routine practice in many different types of cancer. Pre-operative and post-operative values of tumor markers are essential for a proper evaluation. However, tumor marker monitoring of the effect of radiotherapy and chemotherapy has been used very rarely, mostly only for research purposes. Besides monitoring by classical tumor markers, monitoring by markers of angiogenesis and apoptosis seem to be promising for the assessment of chemotherapy effect. Measurement of circulating cancer cells by means of mRNA also seems to be intriguing for therapy effect control and monitoring of the course of disease. Unfortunately, the routine use of these methods has been applied in only a few institutes worldwide. A completely different situation has been observed in palliative treatment. In most cases, changes of serum levels of tumor markers correlate with therapy effect. Thus, the effect of treatment on tumor proliferation can be successfully estimated by decreasing tumor marker levels. For the control of tumor therapy effect we use various monitoring methods (X-ray, ultrasonography, isotopic, or their combination). These methods facilitate the assessment of therapeutic response, provided that there is a suitable anatomical localization of the tumor. The change of tumor mass must, at the same time, be larger than the detection limit of the method (1, 2). However, using monitoring methods cannot detect the presence of a minimal amount of residual tumor tissue, so they cannot be used for monitoring the effect of the therapy used (3). The aim of our study was to find out how tumor biological activity assessment may be used for monitoring the effect of antitumor therapy. Materials and Methods