paediatrics Brussels 17

68

McGuire et al.

TABLE IV. Univariate Comparison of Survival by Radiotherapy for Each Primary Tumor Site, n ¼ 339 Radiation No radiation

5-year survival (%)

5-year survival (%)

n Median (mo)

SE (%)

n

Median (mo)

SE (%)

P -value*

Supratentorial Infratentorial

65

120.0 116.0

54.0 57.1 95.0

7.0 5.2 4.9

38 68 32

190.0

68.0 48.2 80.0

8.6 7.1 8.4

0.95

116

43.0

0.018

Spinal

20

—

—

0.82

n, number of children; mo, months, SE, standard error. *Logrank Test.

there was no statistically significant difference in the two results, the lack of site classification was judged to be random and made exclusion of these cases from any analysis examining location reasonable. In a retrospective, observational study, it is always possible that other confounding variables were not incorporated into the analysis and influenced the results. Potential prognostic factors such as stage, extent of surgical resection, histologic grade, and specific details of all treatments are not consistently available over three decades in the SEER database, and therefore could not be included in our multivariate analysis. Specifically, histologic grade was not analyzed in our study because there is wide variation among institutions in tumor grading and most registrars encode ependy- momas as ‘‘ependymomas,’’ regardless of whether well-differ- entiated or anaplastic. Finally, advances in medicine, including new surgical technologies, evolution of computed tomography and then magnetic resonance imaging as well as revision of pathology classification schema, have occurred during the time period examined and may lead to reporting bias. Despite these limitations, our study demonstrates how survival varies by age, location, and radiotherapy. Understanding these trends may help us further understand the biology and guide refinements in the treatment of ependymoma. Distinct knowledge of how radiation and tumor location relate to survival may guide clinical management of ependymoma in these populations, perhaps leading to modification of treatment guidelines for young children. REFERENCES 1. Kricheff II, Becker M, Scheneck SA, et al. Intracranial ependy- momas: Factors influencing prognosis. J Neurosurg 1964;21:7–14. 2. Farwell JR, Dohrmann GJ, Flannery JT. Central nervous system tumors in children. Cancer 1977;40:3123–3132. 3. Dohrmann GJ, Farwell JR. Ependymal neoplasms in children. Trans Am Neurol Assoc 1976;101:125–129. 4. Ries LAG, Melbert D, Krapcho M, et al. editors. SEER Cancer Statistics Review, 1975–2004. Bethesda, MD: National Cancer Institute 2007. http://seer.cancer.gov/csr/1975_2004/, based on November 2006 SEER data submission, posted to the SEER web site. 5. Central Brain Tumor Registry of the United States data, 1998– 2002. URL http://www.cbtrus.org/factsheet/factsheet.html. 6. Gurney JG, Smith MA, Bunin GR. CNS and miscellaneous intracranial and intraspinal neoplasms. Ries LAG, Smith MA, Gurney JG, et al. editors. Cancer Incidence and Survival Among ACKNOWLEDGMENT Courtney McGuire was supported by the Stanford University Medical Scholars Program.

radiation only for infratentorial tumors, while radiotherapy was not associated with a difference in survival for spinal and supratentorial tumors. While our data are retrospective and treatments were not assigned randomly, radiotherapy appears beneficial for infratento- rial ependymoma, counter to some prior speculation [14]. Recent work by Taylor et al. [18] suggests that specific progenitor cells may contribute to the formation of the distinct tumor types occurring in the supratentorial, infratentorial and spinal regions. Our study found spinal tumors were associated with a significantly better prognosis than both supratentorial and infra- tentorial tumors, but no difference was observed when comparing supratentorial to infratentorial tumors. Similar findings suggesting no difference in survival among supratentorial and infratentorial locations were shown in a recent study by Shu et al. [8] Together these findings suggest that spinal tumors may represent a distinct biological entity, but are not particularly supportive of infratentorial and supratentorial tumors as entirely distinct. One limitation of our study was the inability to specify location for tumors identified as ventricle, overlapping brain, brain not otherwise specified, overlapping, or not otherwise specified (715, 718, 719, 728, and 729). When analyzing how location affects survival, these specific cases were eliminated because of the inability to assign them to supratentorial, infratentorial, or spinal. In order to ensure that there was no systematic error associated with this determination, univariate location analysis was repeated with all the indeterminate cases included and classified as infratentorial. The result was compared to a second univariate analysis completed with all the indeterminate cases classified as supratentorial. Because

1.0

XRT No XRT

0.8

0.6

0.4

0.2

Cumulative survival

0.0

0.00

100.00

200.00

300.00

400.00

Total survival time (months)

Fig. 3. Comparison of survival by radiotherapy for infratentorial tumors. XRT ¼ radiotherapy. Total number of patients ¼ 184. Number of patients in each arm: XRT ¼ 116, no XRT ¼ 68. Logrank Test, P ¼ 0.018.

Pediatr Blood Cancer DOI 10.1002/pbc