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.

Changes of thymidine kinase (TK) during adjuvant and palliative chemotherapy.

UNLABELLED: Thymidine kinase is involved in nucleic acid synthesis and is, therefore, considered to be an important proliferation tumor marker. For this reason, we monitored this marker in the course of colorectal cancer chemotherapy. MATERIALS AND METHODS: We examined thymidine kinase (TK) levels in 30 patients with colorectal cancer who underwent adjuvant or palliative chemotherapy (CHT schemes). The condition for being included in the study was a minimum of 3 cycles of chemotherapy. TK was always assessed with radio-receptor analysis, before and after every chemotherapy cycle, together with other tumor markers. RESULTS: From the monitored tumor markers, only TK changed typically in the course of chemotherapy. In adjuvant chemotherapy, it was mostly low at the beginning of the cycle and its values usually increased considerably at the end. On the other hand, in palliative chemotherapy the dynamics of TK varied mainly depending on the effect of the therapy. Other tumor markers showed nonstandard behavior and minimal correlation with TK changes. CONCLUSION: Thymidine kinase seems to be a suitable parameter for monitoring the effect of adjuvant and palliative chemotherapy in colorectal cancer.

Markers of cellular adhesion in diagnosis and therapy control of colorectal carcinoma.

AIM: Early diagnosis of the progressive tumor disease and control of the effect of therapy in colorectal carcinoma are most frequently performed by monitoring CEA or CA 19-9 tumor markers. Their clinical application is, however, limited. The aim of our study was to demonstrate the contribution of adhesive molecule assessment to the early diagnosis of progression. We also wanted to find out if changes in the levels of cellular adhesion parameters correlate with the effect of antitumor therapy. MATERIALS AND METHODS: Intercellular cell adhesive molecule-1 (ICAM-1) and Vascular cell adhesive molecule-1 (VCAM-1) were assessed using the ELISA method, and the results were correlated with CEA and CA 19-9 tumor markers. Three hundred and sixty-four patients with colorectal carcinoma in Dukes' stages B-D were monitored. The results were processed with the SAS 6.2. statistical program and Statistica. RESULTS: In 92 patients with first clinical progression (occurrence of distant metastases irrespective of localization), significantly increased ICAM-1 and VCAM-1 values were demonstrated. In ROC evaluation of curves, we also demonstrated high sensitivity of adhesive molecules against both the control healthy group (n =89) and the no evidence of disease group (NED) (n=183). Adhesive molecule levels were closely connected with the type and course of therapy and are presented in the form of case reports. CONCLUSION: Soluble adhesive molecules are a prospective parameter both for the early diagnosis of progression and for control of the effect of therapy. There is a need for a large-scale study, preferably multicentric, which would verify the suitability of introducing cellular adhesion parameter assessment into routine practice.

Criteria for the selection of referential groups in tumor marker statistical evaluation on the basis of a retrospective study.

The authors of this study are concerned with the analysis of optimal criteria for the selection of referential groups in the statistical evaluation of tumor markers for early detection of recurrent disease. Although criteria for the selection of optimal referential groups have already been published on a number of occasions (EGTM recommendation), these criteria are not followed in daily routine, which leads to a false interpretation of results and the impossibility of comparing individual studies. The commonest problem is an incorrect determination of cut-off, caused by not following the recommended specificities at 95%, which results in an incorrect assessment of tumor marker sensitivities. Other faulty interpretations happen in consequence of inaccurate and not clearly defined referential groups, which differ from each other by, for example, stage of the disease, length of the follow-up and so on. Comparing tumor marker results still remains a problem, since they are assessed with diagnostic kits from different manufacturers which may misrepresent the final value of the results, and thus imitate remission or progression of the tumor disease. Similarly, mutual comparison of results from prospective and retrospective studies without standardization of clinical conditions leads to an unreliable interpretation. The authors show, through concrete examples, the possibility of a completely different interpretation of the results in identical referential groups in consequence of their inaccurate characteristics.