Stage Information for CNS Embryonal Tumors
Staging of Medulloblastoma
Historically, staging was based on an intraoperative evaluation of both the size and extent of the tumor, coupled with postoperative neuroimaging of the brain and spine and cytological evaluation of cerebrospinal fluid (CSF) (the Chang system). Intraoperative evaluation of the extent of the tumor has been supplanted by neuraxis imaging prior to diagnosis and postoperative imaging to determine amount of primary site residual disease. The following tests and procedures are now used for staging:
The tumor extent is defined as:
- M0—no dissemination.
- M1—CSF-positive cytology only.
- M2—gross nodular seeding in cerebellar-cerebral subarachnoid space and/or lateral or third ventricle.
- M3—gross nodular seeding in spinal subarachnoid space.
- M4—extraneural metastasis.
Postoperative degree of residual disease is designated as:
- Gross-total resection/near-total resection—no or minimal (not measurable) evidence of residual disease after diagnosis.
- Subtotal resection—residual disease after diagnosis; this is conventionally further subdivided into less than, greater than, or equal to 1.5 cm2 of measurable residual disease.
- Biopsy—no tumor resection; only a sample of tumor tissue is removed.
The presence of diffuse (>50% of the pathologic specimen) histologic anaplasia has been incorporated as an addition to staging systems. If diffuse anaplasia is found, patients with otherwise average-risk disease are up-staged to high-risk disease.
Staging of CNS Primitive Neuroectodermal Tumors (PNETs)
Patients with CNS PNETs are staged in a fashion similar to that used for children with medulloblastoma; however, the patients are not assigned to average-risk and high-risk subgroups for treatment purposes (refer to the Staging of Medulloblastoma section of this summary for more information).
Staging of Medulloepithelioma and Ependymoblastoma
Dissemination of both medulloepitheliomas and ependymoblastomas frequently occurs.[5,6] The tumors are staged in the same way as medulloblastoma; however, the patients are not assigned to average-risk and high-risk subgroups for treatment purposes (refer to the Staging of Medulloblastoma section of this summary for more information).
Staging of Pineoblastoma
Dissemination at the time of diagnosis occurs in 10% to 30% of patients. Because of the location of the tumor, total resections are uncommon, and most patients have only a biopsy or a subtotal resection before postsurgical treatment.[7,8] Staging for children with pineoblastomas is the same as that performed for children with medulloblastoma; however, the patients are not assigned to average-risk and high-risk subgroups for treatment purposes (refer to the Staging of Medulloblastoma section of this summary for more information).
- Fouladi M, Gajjar A, Boyett JM, et al.: Comparison of CSF cytology and spinal magnetic resonance imaging in the detection of leptomeningeal disease in pediatric medulloblastoma or primitive neuroectodermal tumor. J Clin Oncol 17 (10): 3234-7, 1999. [PUBMED Abstract]
- Zeltzer PM, Boyett JM, Finlay JL, et al.: Metastasis stage, adjuvant treatment, and residual tumor are prognostic factors for medulloblastoma in children: conclusions from the Children's Cancer Group 921 randomized phase III study. J Clin Oncol 17 (3): 832-45, 1999. [PUBMED Abstract]
- Yao MS, Mehta MP, Boyett JM, et al.: The effect of M-stage on patterns of failure in posterior fossa primitive neuroectodermal tumors treated on CCG-921: a phase III study in a high-risk patient population. Int J Radiat Oncol Biol Phys 38 (3): 469-76, 1997. [PUBMED Abstract]
- Taylor RE, Bailey CC, Robinson K, et al.: Results of a randomized study of preradiation chemotherapy versus radiotherapy alone for nonmetastatic medulloblastoma: The International Society of Paediatric Oncology/United Kingdom Children's Cancer Study Group PNET-3 Study. J Clin Oncol 21 (8): 1581-91, 2003. [PUBMED Abstract]
- Gerber NU, von Hoff K, von Bueren AO, et al.: Outcome of 11 children with ependymoblastoma treated within the prospective HIT-trials between 1991 and 2006. J Neurooncol 102 (3): 459-69, 2011. [PUBMED Abstract]
- Müller K, Zwiener I, Welker H, et al.: Curative treatment for central nervous system medulloepithelioma despite residual disease after resection. Report of two cases treated according to the GPHO Protocol HIT 2000 and review of the literature. Strahlenther Onkol 187 (11): 757-62, 2011. [PUBMED Abstract]
- Jakacki RI, Zeltzer PM, Boyett JM, et al.: Survival and prognostic factors following radiation and/or chemotherapy for primitive neuroectodermal tumors of the pineal region in infants and children: a report of the Childrens Cancer Group. J Clin Oncol 13 (6): 1377-83, 1995. [PUBMED Abstract]
- Timmermann B, Kortmann RD, Kühl J, et al.: Role of radiotherapy in the treatment of supratentorial primitive neuroectodermal tumors in childhood: results of the prospective German brain tumor trials HIT 88/89 and 91. J Clin Oncol 20 (3): 842-9, 2002. [PUBMED Abstract]