The use and significance of biologic markers in the evaluation and staging of a child with cancer

Recent advances in neuroblastoma

PURPOSE OF REVIEW

Although there have been recent advances with multimodal therapy, treatment of neuroblastoma remains a clinical challenge. Despite the identification of several genetic features, there has not been a significant increase in 5-year survival in the last decade. This review will highlight the current operative strategies along with new research developments aimed at improving survival.

RECENT FINDINGS

The goal of surgical intervention in the early stages of neuroblastoma is complete curative resection. In advanced-stage disease, tissue biopsy for staging is the initial goal. In recent years, minimally invasive surgery (MIS) is considered in carefully selected patients. Recent advances in neuroblastoma research have focused on tyrosine kinase inhibition, differentiation, pathway inhibition, and immunotherapy. Several of these targets have shown promising results in vivo and are currently under investigation for potential clinical trials.

SUMMARY

New information on the importance of cell signaling and the targeting of specific genes of interest are providing key insights into neuroblastoma. Only through the discovery of novel treatment strategies made available through the advancement of research will neuroblastoma be survivable for patients with advanced-stage disease.

Neuroblastoma

Neuroblastomas continue to remain a clinical challenge, despite advances in multimodal therapy. Currently, studies are aimed at novel targets for neuroblastoma directed toward poor prognostic indicators such as the MYCN oncogene and marked angiogenesis. There have also been recent discoveries in neuroblastoma pathogenesis involving epigenetic regulation and retinoic acid therapy. Understanding the intricate complexities of this tumor may lead to innovative agents for more effective combinational therapy.

Neuroblastomas in Denmark 1943-80. Epidemiological and clinical studies

Two-hundred-and-fifty patients were registered in a population-based study of neuroblastomas in Denmark in the period 1943-80. The major epidemiological findings were an increased incidence with an unchanged mortality rate during the study period. The increase in incidence related solely to children 0-4 years of age and was most pronounced in infants under 1 year of age. Several reasons for the observed epidemiological rates include (i) changes in the composition of the population, (ii) improved diagnostic procedures, (iii) a shift in the diagnostic criteria, and (iv) an increase in environmental carcinogens of importance in the induction of neuroblastoma. Associated with an increased risk were lower socio-economic levels and young or advanced parental age, suggesting the importance of environmental as well as genetic factors for the induction of neuroblastoma. The epidemiological findings of an increased incidence with an unchanged mortality rate, which suggests the inclusion of borderline lesions in recent years, are of major importance in interpreting the results of mass screening for the disease. The clinical findings in 253 patients treated in Denmark from 1943 to 1980 (including 5 patients resident outside Denmark and excluding 2 patients without available hospital records) were analysed. The major finding was a zero-time shift, that is, earlier diagnosis of the disease during the study period, with increasing survival rates from decade to decade mostly due to a better age and stage distribution, a zero-time shift which was also apparent in the changes of the symptomatology. Independent prognostic variables were age, stage, and treatment with chemotherapy for children over 1 year of age with stage II disease, and for infants with stages III-IV disease. Analysis of data from a subset of the 253 children suggested that high proliferative activity detected by flow cytometry may be an important prognostic variable. The study also suggests that the pattern of metastatic spread might have changed as a consequence of prolonged survival obtained by improved treatment modalities, stressing the importance of a high frequency of autopsy among cancer patients. Hypotheses generated by the study included (i) that most neuroblastomas might be congenital, (ii) that the age influence on prognosis might be explained in terms of growth rate, cell cycle transit time, and duration of the disease, and (iii) that some neuroblastomas might be borderline lesions.

Neuropeptide Y in neuroblastoma: increased concentration in metastasis, release during surgery, and characterization of plasma and tumor extracts

Five children with neural crest tumors (two ganglioneuromas, one ganglioneuroblastoma, and two neuroblastomas) were investigated regarding neuropeptide Y-like immunoreactivity (NPY-LI) in tumor tissue and plasma at diagnosis and during surgery. Radioimmunoassay of extracted plasma revealed higher NPY-LI at diagnosis of neuroblastoma (640 and 230 pmol/L resp) than ganglioneuroblastoma or ganglioneuroma (74, 45, and 26 pmol/L resp). During surgery of neuroblastoma plasma NPY-LI increased two- to four-fold while no peroperative increase was seen in the other children. NPY-LI was considerably higher in neuroblastoma tissue (220 pmol/g and 144 pmol/g) than in ganglioneuroblastoma (40.2 pmol/g), ganglioneuroma (0.6 and 4.4 pmol/g), or healthy adrenal tissue (5.5 pmol/g). The highest NPY-LI concentration was found in neuroblastoma metastasis, 3,091 pmol/g. Gel-permeation chromatography of a neuroblastoma tumor showed that a majority of NPY-LI was representing intact NPY (NPY 1-36) while metastasis and plasma from the same child mainly contained smaller immunoreactive fragments. High concentrations of systemic NPY in neuroblastoma patients are of tumoral origin. Plasma levels of NPY and its fragments can be useful in diagnosing and monitoring neuroblastoma, and for early detection of relapse or metastatic disease. A possible involvement of NPY in neuroblastoma tumor growth and spread deserves further investigation.

Biological and NMR markers for cancer

The search for a universal tumor marker continues. Present markers range from tumor products (polyamines, glycoproteins, peptides, hormones or carbohydrate-linked markers) to reaction products produced by the host tissues during tumor invasion. Techniques used to identify them include the classical methods of histology and cytochemistry as well as the more recent radioimmunoassay and metabolic probes. The in vivo techniques of increasing use for patient monitoring are MRS (magnetic resonance spectroscopy) and MRI (magnetic resonance imaging). The efficiency of some markers and statistical methods used in analyzing data are discussed, as are the ethical problems surrounding the use of new testing methods. Recent developments in MRI and MRS, marker elucidation, and evidence for a new autocrine differentiation-inhibiting factor (ADIF) are reviewed. Future needs and approaches focus on greater utilization of indicators of the preneoplastic state and of risk to cancer, as well as more careful attention to statistical analysis.