Clinical and Laboratory Evaluation 751 Staging

Disease stage is a powerful prognostic factor in neu-roblastoma (Table 7.5). In 1988 an international staging proposal was developed, which was further refined in 1993 (Brodeur et al. 1993). The INSS has been readily accepted worldwide; therefore, other staging systems that were used to determine extent of disease in the past, such as the Evans' staging system, the Pediatric Oncology Group staging system, and the TMN system, are not discussed in this chapter (Evans et al. 1971; Castleberry et al. 1994; Ng and Kingston 1993). The INSS is a surgical-based staging system (Table 7.6), although modern imaging tools together with the estimation of an experienced pediatric surgeon is likely to achieve the same stage category in almost all cases. The criterion "crossing the midline" for discriminating between stage 2 and stage 3 is described as the infiltrative contiguous extension beyond the opposite side of the vertebral bodies. Characteristically, these tumors encompass large vessels and other vital structures. A tumor just overhanging the midline (e.g., large adrenal tumors) would not be sufficient for stage-3 categorization.

Although it was anticipated that the introduction of new sensitive diagnostic techniques (e.g., of MIBG scintigraphy and immunocytology or PCR for

Table 7.5. International Neuroblastoma Staging System (INSS) (Brodeur et al. 1993)

Stage Definition

Stage 1 Localized tumor confined to the area of origin. Complete gross resection with or without microscopic residual disease; identifiable ipsilateral and contralateral lymph node negative for tumor. Adherent lymph nodes in direct continuity with and removed with the tumor may be positive for the tumor. A grossly resected midline tumor without ipsilateral (with: stage 2A) or contralateral (with: stage 2B) lymph node involvement is considered stage 1

Stage 2A Unilateral with incomplete gross resection; identifiable ipsilateral and contralateral lymph node negative for tumor

Stage 2B Unilateral with complete or incomplete gross resection; with ipsilateral lymph node positive for tumor; identifiable contralateral lymph node negative for tumor

Stage 3 Tumor infiltrating across midline with or without regional lymph node involvement; or unilateral tumor with contralateral lymph node involvement or midline tumor with bilateral lymph node involvement

Stage 4 Dissemination of tumor to distant lymph nodes, bone marrow, liver, or other organs except as defined in stage 4S

Stage 4S Localized primary tumor as defined for stage 1 or 2 with dissemination limited to liver, skin, and bone marrow (<10% of nucleated marrow cells are tumor cells)

Table 7.6. Variation of the relative stage incidence under and over 1 year of age in Japan (J; Ikeda et al. 2002),Germany (G) and United Kingdom (UK;Pearson and Philipp 2000),and North America (NA)

INSS stage

All ages

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