Serum markers in small cell lung cancer: opportunities for improvement

Lung cancer is one of the leading causes of death from malignancy worldwide. In particular small cell lung cancers, which comprise about 15-20% of all lung cancers, are extremely aggressive and cure rates are extremely low. Therefore, new treatment modalities are needed and detection at an early stage of disease, as well as adequate monitoring of treatment response is essential in order to improve outcome. In this respect, the use of non-invasive tools for screening and monitoring has gained increasing interest and the clinical applicability of reliable, tumor-related substances that can be detected as tumor markers in easily accessible body fluids is subject of intense investigation. Some of these indicators, such as high LDH levels in serum as a reflection of the disease, have been in use for a long time as a general tumor marker. To allow for improved monitoring of the efficacy of new therapeutic modalities and for accurate subtyping, there is a strong need for specific and sensitive markers that are more directly related to the biology and behavior of small cell lung cancer. In this review the current status of these potential markers, like CEA, NSE, ProGRP, CK-BB, SCC, CgA, NCAM and several cytokeratins will be critically analyzed with respect to their performance in blood based assays. Based on known cleavage sites for cytoplasmic and extracellular proteases, a prediction of stable fragments can be obtained and used for optimal test design. Furthermore, insight into the synthesis of specific splice variants and neo-epitopes resulting from protein modification and cleavage, offers further opportunities for improvement of tumor assays. Finally, we discuss the possibility that detection of SCLC related autoantibodies in paraneoplastic disease can be used as a very early indicator of SCLC.

The concentration of selected cancer markers (TPA, TPS, CYFRA 21-1, CEA) in workers occupationally exposed to arsenic (As) and some heavy metals (Pb, Cd) during a two-year observation study

OBJECTIVE

Molecular epidemiology studies have lately been focused on occupational cancer associated with exposure to chemical carcinogens in work environment. Measuring serum levels of tumour markers ie. the substances produced in transformed cells, is a modern method used in the prevention or early detection of cancer. A two-year observation study was constructed to investigate the relationship between arsenic, lead, and cadmium concentrations and the levels of cancer markers: TPA (tissue polipeptide antigen), TPS (tissue polipeptide specific antigen), and CYFRA 21-1 in 69 male workers occupationally exposed to As and Pb, and environmentally exposed to Cd via tobacco smoking.

RESULTS

Significant correlations were found between CEA and blood Cd concentrations or between CEA and period of work under exposure. Multiple regression tests revealed also relationships between some cancer markers and the work period, and thereby the lifetime exposure to heavy metals. Duration of work under exposure significantly influenced TPA and TPS concentrations in these models. All the metals examined were found to have influence on the concentration of cancer markers, except for CYFRA 21-1, but the direction of this influence varied. Lead (especially FEP level) and cadmium were also among the metals affecting TPA concentration profile, although the multiple regression ratio for Cd-TPA correlation was negative.

CONCLUSIONS

The strong positive correlation between blood concentrations of Cd and CEA, the marker of abnormal cellular differentiation, may reflect neoplastic transformation of normal cells stimulated by some carcinogens (e.g. cadmium). All the examined carcinogenic, or potentially carcinogenic metals (As, Cd, Pb) belong to the group of factors having impact on serum TPS and/or TPA concentrations in exposed workers. No correlation was found between CYFRA 21-1 and any metal studied but it is plausible that changes in the concentration level of this marker might be revealed after a longer observation period.

Quantitative measurement of soluble cytokeratin fragments in tissue cytosol of 599 node negative breast cancer patients: a prognostic marker possibly associated with apoptosis

Apoptosis is associated with caspase-mediated proteolysis of Type I (K18 and K19) cytokeratins. We previously showed a positive association between the levels of tissue polypeptide antigen (TPA), that recognizes cytokeratins K8, K18, and K19 fragments, and induced apoptosis in breast cancer cell lines. The aim of the present study was to evaluate the interrelationships between TPA, steroid receptors, and p53, and their joint prognostic role in node-negative breast cancer patients not treated with adjuvant therapies. Age and pT were also considered since they are known prognostic factors. Five hundred and ninety-nine cases with N- breast cancer were evaluated (median follow-up: 60 months). TPA was measured by an immunoradiometric assay and p53 by an immunochemiluminescent assay in tumor cytosol. Multiple correspondence analysis was used to study the associations among variables. Their prognostic role (univariate analysis) and their joint effect (multivariate analysis) on RFS were investigated with Cox regression models. TPA showed a direct association with ER and PgR. Higher p53 values were weakly associated to low values of ER, PgR, and TPA. Younger age was related to low and intermediate values of ER and PgR and to low p53 values, while older age was related to high values of ER. Multivariate analysis showed a significant prognostic impact for pT, age, ER, and TPA. Among the interactions considered clinically relevant, only that between ER and age was found. RFS estimated values were poorer in cases with lower than in those with higher TPA values, both in patients expected to have a poor (pT2, young age, low ER) and a better prognosis (pT1, older age, high ER). From the findings of the present study we can draw the following conclusions: The relationship of TPA with prognosis gives an additional contribution to pT, age, and steroid receptors in N- breast cancer; TPA may be considered the first marker of apoptosis measured with a fully standardized quantitative method in tumor cytosol and could be evaluated in prognostic indexes including markers related to different biological mechanisms.