Biological aspects of neuroblastomas identified by mass screening in Quebec

BACKGROUND

Neuroblastoma has several characteristics that suggest that preclinical diagnosis might improve outcome. Therefore, the Quebec Neuroblastoma Screening Project was undertaken from 1989 to 1994 to examine infants at 3 weeks and 6 months by measuring urinary catecholamine metabolites.

PROCEDURE

Over the 5-yr period, 45 tumors were detected by screening, 20 were identified clinically prior to the third week, and 64 were identified clinically at a later time. We analyzed available tumors for Shimada histopathology, tumor ploidy, MYCN copy number and serum ferritin.

RESULTS

Of the tumors detected by screening, only 2 of 45 tested had unfavorable histology, 2 of 45 had diploid or tetraploid DNA content, 0 of 43 had MYCN amplification, and 4 of 44 had elevated serum ferritin. All of these patients are alive and well. The 20 patients detected prior to the 3-week screen had similar biological characteristics. In contrast, of the patients detected clinically after 3 weeks of age, 19 of 51 testedhad unfavorable histology, 25 of 66 had diploid or tetraploid tumors, 12 of 56 had MYCN amplification, and 14 of 54 had elevated ferritin.

CONCLUSIONS

The difference between the screened and clinically detected cases was highly significant for each biological variable. Preliminary data on other biological variables, such as neurotrophin expression and allelic loss on 1 p in these patients are consistent with the above findings. These data suggest that mass screening for neuroblastoma at or before 6 months of age detects almost exclusively tumors that have favorable biological characteristics, many of which might have regressed spontaneously. Thus, continued mass screening for neuroblastoma at 6 months is unlikely to accomplish its intended goal, and should probably be discontinued.

Screening for neuroblastoma is ineffective in reducing the incidence of unfavourable advanced stage disease in older children

Neuroblastoma exhibits many characteristics which would suggest that preclinical detection may improve outcome. The Quebec Neuroblastoma Screening Project was initiated to determine whether mass screening could reduce mortality in a large cohort of infants. All 476,603 children born in the province of Quebec during a 5-year period of time (1 May 1989 to 30 April 1994) were eligible for determinations of urinary catecholamine metabolites at 3 weeks and 6 months of age. Children with positive screening were referred to one of four paediatric cancer centres in Quebec for uniform evaluation and treatment. Standardised incidence ratios (SIRs) were calculated for neuroblastoma in Quebec and two comparable population-based controls during the same period of time using similar ascertainment procedures. Compliance with screening in Quebec was 91% at 3 weeks (n = 425,816) and 74% at 6 months (n = 349,706). Up to 31 July 1995 with a follow-up of the birth cohort of 15-75 months, 118 cases of neuroblastoma were diagnosed, 43 detected preclinically by screening, 20 detected clinically prior to screening at 3 weeks of age and 55 detected clinically after 3 weeks of age having normal screens (n = 52) or never screened (n = 3). Based on data from concurrent control populations, 54.5 cases of neuroblastoma would have been expected in Quebec during the study period for an SIR of 2.17 (95% CI 1.79-2.57, P < 0.0001). For the two control groups, the overall SIR was 1.00 (NS). SIRs for Quebec by age at diagnosis in yearly intervals show a marked increased incidence under 1 year of age (SIR = 2.85, 95% CI 2.26-3.50), with no reduction in incidence in subsequent years. We conclude that screening for neuroblastoma markedly increases the incidence in infants without decreasing the incidence of unfavourable advanced stage disease in older children. It is unlikely that screening for neuroblastoma in infants will reduce the mortality of this disease.

A population-based study of the usefulness of screening for neuroblastoma

BACKGROUND

Neuroblastoma has many characteristics which suggest that preclinical detection might improve outcome. The Quebec Neuroblastoma Screening Project was initiated to determine whether mass screening could reduce mortality in a large cohort of infants. As an early endpoint, we report whether screening could reduce the incidence of poor-prognosis neuroblastoma in children with advanced-stage disease over 1 year of age.

METHODS

All 476,603 children born in the province of Quebec during the 5-year period of May 1, 1989, to April 30, 1994, were eligible for urinary assay of homovanillic acid and vanillylmandelic acid at 3 weeks and 6 months of age. Children with a positive screen were referred to one of four paediatric cancer centres in the province for uniform evaluation and treatment if necessary. Standardised incidence ratios (SIRs) were calculated for neuroblastoma in the province and two similar population-based controls, the state of Minnesota and the province of Ontario, during the same period of time and with similar ascertainment procedures.

FINDINGS

Compliance with screening in Quebec province was 91% at 3 weeks (n = 425,816) and 74% at 6 months (n = 349,706). Through July 31, 1995, with a follow-up of the birth cohort of 15-75 months, 118 cases of neuroblastoma were diagnosed, 43 detected preclinically by screening, 20 detected clinically before screening at 3 weeks of age, and 55 detected clinically after 3 weeks of age having normal screens (52) or never screened (3). Retrospective analysis of stored samples confirmed that 49 of 52 patients missed by screening had levels of catecholamine metabolites that were too low to be detected at 6 months or earlier. Based on US Surveillance, Epidemiology and End Results data, 54.5 cases of neuroblastoma would have been expected in Quebec province during the study period, for an SIR of 2.17 (95% CI 1.79-2.57, p < 0.0001). For the two control groups, 43 and 80 cases of neuroblastoma were detected, respectively, compared with 37.9 and 85.4 expected, overall SIR 1.00 (not significant). SIRs for Quebec province by age at diagnosis in yearly intervals show a marked increased incidence under 1 year of age (SIR 2.85, 2.26-3.50), with no reduction in incidence in subsequent years. Limiting analysis to only patients diagnosed over 1 year of age with advanced-stage disease, 22 cases were detected in Quebec province versus 14.4 expected (SIR 1.52, 0.95-2.23). Data in the two control groups show no significant increase or decrease in any-stage disease in children under or over the age of 1 year, except for an increase in early-stage disease in Minnesota children over 1 year: 10 versus 3.8 expected (SIR 2.67, 1.27-4.58).

INTERPRETATION

Screening for neuroblastoma increases the incidence in infants without decreasing the incidence of unfavourable advanced-stage disease in older children. It is unlikely that screening for neuroblastoma in infants will reduce mortality for this disease.