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International Neuroblastoma Staging System (INSS):


This is a staging system based largely on surgical findings - but not for Stages 4 and 4S.

Stage I

  • Localized tumor with complete gross excision with or without microscopic residual disease
  • Negative ipsilateral lymph nodes


Stage 2A

  • Localized tumor with incomplete gross resection
  • Negative ipsilateral lymph nodes


Stage 2B

  • Localized tumor with or without gross resection
  • Positive ipsilateral lymph nodes
  • Negative contralateral lymph nodes


Stage 3

  • Unresectable unilateral tumor infiltrating across the midline with or without regional lymph node involvement
  • Localized unilateral tumor with contralateral lymph node involvement
  • Midline tumor with bilateral extension by infiltration or by lymph node involvement


Stage 4

  • Any primary tumor with dissemination to distant lymph nodes, bone, bone marrow, skin, liver or other organs (does not include 4S)


Stage 4S

  • Localized primary tumor (as defined by stage 1, 2A, 2B) with dissemination limited to skin, liver, bone marrow



  • Limited to infants  < 1 yr of age
  • Bone marrow involvement in Stage 4S should be minimal, i.e. less than 10% of total nucleated cells identified as malignant on bone marrow biopsy or marrow aspirate. More extensive marrow involvement would be considered to be Stage 4. The MIBG scan (if performed) should be negative in the marrow.



Multifocal primary tumors (e.g., bilateral adrenal primary tumors) should be staged according to the greatest extent of disease, as defined above, and followed by a subscript “M” (e.g. 3M).

The midline is defined as the vertebral column. Tumors originating on one side and crossing the midline must infiltrate to or beyond the opposite side of the vertebral column.

Proven malignant effusion within the thoracic cavity if it is bilateral or the abdominal cavity upstages the patient to INSS 3.


Stage 4S

  • Special assignment to children less than 1 year of age
  • Metastases limited to skin, liver and bone marrow biopsy
  • May spontaneously regress
  • Associated with good prognosis


Stage is an important predictor of outcome:


5 - 10 year Survival


Nearly all patients survive

2 and 4S



50 - 70%

4 and over 1 year old

Only 5 - 10%



There is also an International Neuroblastoma Risk Group (INRG) Staging System - which was designed only to look at anatomical staging and not to include surgical findings. This system is not used very often in clinical practice.


Stage Description
  • Localized tumor not involving vital structures (there is a list of image defined risk factors to assess this) and confined to one body compartment
  • Loco-regional disease with the presence of one or more image defined risk factors


  • Distant metastatic disease  (except stage MS)


  • Metastatic disease in children less than 18 months old with metastases confined to skin, liver and/or bone marrow (<10%)




INSS at the NCI



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