Where should neuroblastoma mass screening go?

Overdiagnosis in urologic cancer : For World Journal of Urology Symposium on active surveillance in prostate and renal cancer

BACKGROUND

Cancer, which historically was diagnosed at late and incurable stages, has expanded to a heterogeneous group of conditions that vary from clinically insignificant to rapidly aggressive and lethal. This evolution is due to the widespread use of screening tests for early detection of cancer, both directed (i.e., PSA, mammography, colonoscopy) and undirected (abdominal imaging). The use of these tests has resulted in both benefits and harms. The benefits are a reduction in survival and mortality, due to significant cancers being diagnosed at a more curable stage. The harms are an increase, in some cases dramatic, in the diagnosis of clinically insignificant disease. These are called 'cancer' but not destined to affect the patient's life, even in the absence of treatment.

METHODS

Non-explicit summary of the literature on overdiagnosis of cancer.

RESULTS

The phenomenon of overdiagnosis requires two factors: the presence of a common reservoir of microfocal disease and a screening test to find it. These factors exist for breast, prostate, skin, renal, and thyroid cancers, and to a lesser degree for lung cancer. The problem of cancer overdiagnosis and overtreatment is complex, with numerous etiologies and many tradeoffs. It is a particular problem in prostate cancer but is a major issue in many other cancer sites. Screening for prostate cancer based on the best data from prospective randomized trials significantly reduces cancer mortality. However, reducing overtreatment in patients diagnosed with indolent disease is critical to the success of screening.

CONCLUSION

Active surveillance, the focus of this series of articles, is an important strategy to reduce overtreatment. This article reviews the pathological, clinical, social, and psychological aspects of overdiagnosis in cancer.

Clinical significance of serum biomarkers in pediatric solid mediastinal and abdominal tumors

Childhood cancer is the leading cause of death by disease among U.S. children between infancy and age 15. Despite successes in treating solid tumors such as Wilms tumor, disappointments in the outcomes of high-risk solid tumors like neuroblastoma have precipitated efforts towards the early and accurate detection of these malignancies. This review summarizes available solid tumor serum biomarkers with a special focus on mediastinal and abdominal cancers in children.

Overdiagnosis in cancer

This article summarizes the phenomenon of cancer overdiagnosis-the diagnosis of a "cancer" that would otherwise not go on to cause symptoms or death. We describe the two prerequisites for cancer overdiagnosis to occur: the existence of a silent disease reservoir and activities leading to its detection (particularly cancer screening). We estimated the magnitude of overdiagnosis from randomized trials: about 25% of mammographically detected breast cancers, 50% of chest x-ray and/or sputum-detected lung cancers, and 60% of prostate-specific antigen-detected prostate cancers. We also review data from observational studies and population-based cancer statistics suggesting overdiagnosis in computed tomography-detected lung cancer, neuroblastoma, thyroid cancer, melanoma, and kidney cancer. To address the problem, patients must be adequately informed of the nature and the magnitude of the trade-off involved with early cancer detection. Equally important, researchers need to work to develop better estimates of the magnitude of overdiagnosis and develop clinical strategies to help minimize it.

Neural crest development and neuroblastoma: the genetic and biological link

Neuroblastoma is one of the most common pediatric solid tumors originating from the sympathoadrenal lineage of neural crest. The tumor shows extremely different clinical phenotypes such as spontaneous regression on one hand and aggressive growth on the other hand. The different biological behavior of neuroblastoma appears to be determined by the genetic abnormalities including amplification of MYCN oncogene, DNA ploidy and some allelic imbalances. However, the spontaneous regression of neuroblastoma mimics the programmed cell death normally occurring in developing sympathetic cells expressing both TrkA tyrosine kinase A and p75NTR neurotrophin receptor. Indeed, TrkA expression is the most important factor related to the induction of tumor cell differentiation and/or programmed cell death because without its expression spontaneous regression of neuroblastoma never occurs. Thus, the enigmatic clinical behaviors of neuroblastoma are strictly linked to the molecular mechanism of neural crest development.

Neuroblastoma in Europe: differences in the pattern of disease in the UK. SENSE. Study group for the Evaluation of Neuroblastoma Screening in Europe

BACKGROUND

Neuroblastoma is a major contributor to childhood cancer mortality, but its prognosis varies with age and stage of disease, and some tumours regress spontaneously. Urinary screening programmes or clinical examination may detect the disease before symptoms appear, but the benefit of early diagnosis is uncertain. We examined the incidence, pattern, and presentation of neuroblastoma in four European countries.

METHOD

Population-based incidence rates were derived for France, Austria, Germany, and the UK. Age, sex, and stage distribution were analysed by Mantel-Haenszel techniques and Poisson regression. The proportion of incidental diagnoses (cases without symptoms found at routine health checks or during investigation of other disorders) and mortality rates were also compared.

FINDINGS

Between 1987 and 1991, 1672 cases of neuroblastoma were diagnosed in children under 15 years old (France, 624; Austria, 69; Germany, 493; UK, 486). Age-standardised annual incidence was significantly lower in the UK (10.1/million) than in France (12.5) and Germany (11.4). In the UK a deficit of low-stage disease in infants was accompanied by an excess of stage IV in older children. The UK had significantly fewer incidental diagnoses (8%) than Austria (27%) and Germany (34%). UK mortality rates were significantly higher than German or French rates.

INTERPRETATION

In the UK, neuroblastoma diagnosis is delayed, possibly because of a less rigorous system of health checks for children. Although some overdiagnosis occurs in mainland Europe, our data suggest that in the UK some low-stage cases, undetected in infancy, may later present as advanced disease. This finding has implications for screening programmes and organisation of routine surveillance of infant health in the UK.