IN RESPONSE TO DR. BEITLER

To the Editor: We are grateful to Dr. Beitler for his generous commentsabout our work. We very much agree that traditional cervical cancerstaging methods, especially the FIGO system, are inaccurate in determin-ing the extent of disease and in assessing prognosis.

PET scanning is, indeed, a standard and vital part of the workup ofpatients with advanced cervical cancer at our institution. Studies by ourgroup (1, 2) and others (3–5) show that PET is far superior to conventionalmethods in identifying nodal and metastatic disease.

We are now extending our work, recently reported in this journal on theassessment of prognosis (6). It may be possible to achieve similar or evensuperior prognostic information by a simple visual analysis of the PETimages without the need for the specialized software used in Ref 6 (7).

PET also seems to hold great promise in brachytherapy treatment plan-ning (8, 9). After applicator placement and intravenous injection of thePET radiopharmaceutical F-18 fluorodeoxyglucose (FDG), a PET scan isperformed with a tubing filled with FDG placed in the applicator, thuspermitting accurate delineation of the three-dimensional distribution of thetumor in relation to the applicator. Our early work suggests that a substan-tial fraction of brachytherapy patients with large tumors receive an inad-equate dose to part of their tumors. Further research in this area may leadto PET’s becoming an essential part of brachytherapy treatment planning.

As PET continues its rapid expansion in the United States and through-out the developed world, we hope this imaging modality will become aroutine part of the evaluation and treatment of patients with cervical cancer.

TOM R. MILLER, M.D., PH.D.PERRY W. GRIGSBY, M.D.Mallinckrodt Institute of RadiologySt. Louis, MO

PII S0360-3016(02)03824-5

1. Grigsby PW, Dehdashti F, and Siegel BA. FDG-PET evaluation ofcarcinoma of the cervix. Clin Positron Imag 1999;2:105–109.

2. Grigsby PW, Siegel BA, Dehdashti F. Lymph node staging by positronemission tomography in patients with carcinoma of the cervix. J ClinOncol 2001;19:3745–3749.

3. Rose P, Adler L, Rodriguez M, et al. Positron emission tomography forevaluating para-aortic nodal metastasis in locally advanced cervicalcancer before surgical staging: A surgicopathologic study. J Clin Oncol1999;17:41–45.

4. Sugawara Y, Eisbruch A, Kosuda S, et al. Evaluation of FDG-PET inpatients with cervical cancer. J Nucl Med 1999;40:1125–1131.

5. Reinhardt M, Ehritt-Braun C, Vogelgesang D, et al. Metastatic lymphnodes in patients with cervical cancer: Detection with MR imaging andFDG PET. Radiology 2001;218:776–782.

6. Miller TR, and Grigsby PW. Measurement of tumor volume by PET toevaluate prognosis in patients with advanced cervical cancer treated byradiation therapy. Int J Radiat Oncol Biol Phys 2002;53:353–359.

7. Miller T, Pinkus E, and Dehdashti F. Improved prognostic value ofFDG-PET in patients with cervical cancer using a simple visual analysisof tumor characteristics (Abstr). J Nucl Med 2002;43:28P.

8. Mutic S, Grigsby PW, Low DA, et al. PET guided three-dimensionaltreatment planning of intracavitary gynecologic implants. Int J RadiatOncol Biol Phys 2002;52:1104–1110.

9. Malyapa RS, Mutic S, Low DA, et al. Physiologic FDG-PET threedimensional brachytherapy treatment planning for cervical cancer. Int JRadiat Oncol Biol Phys, in press. 2002.

IN RESPONSE TO DRS. SCHILD, WONG, AND NISI,IJROBP 2002;53:787

To the Editor: In a recent letter to the editor, Drs. Schild, Wong, and Nisi(1) were concerned that there might be no other dose–response dataavailable in the literature for treating patients with spinal cord ependymo-

mas. Please see such data that was published more than 20 years ago fromthe Massachusetts General Hospital, which provides this information (2).

GENE KOPELSON, M.D.Trumbull Oncology CenterRadiation Oncology of Southern ConnecticutTrumbull, CT

PII S0360-3016(02)03859-2

1. Schild SE, Wong W, Nisi K. In regard to the radiotherapy of myxo-papillary ependymomas. Int J. Radiat Oncol Biol Phys 2002;53:787.

2. Kopelson G, Linggood RM, Kleinman GM, et al. Management ofintramedullary spinal cord tumors. Radiology 1980;135:473–479; TableV.

IN RESPONSE TO DRS. KOPELSON ET AL.

To the Editor: Dr. Kopelson has kindly identified his dose–response datafor all subtypes and grades of spinal ependymomas in a 1980 study (1). Hisstudy included 12 patients with ependymomas, and of these, 6 had myxo-papillary ependymomas. The dose–response was evaluated in the 8ependymoma patients with a minimum follow-up of 5 years. Of the 3patients who received a time–dose fraction (TDF) of �55, 2 were locallycontrolled. Of the 3 patients who received a TDF 55–65, 2 were locallycontrolled. Of the 2 patients who received a TDF of �65, both were locallycontrolled. There are other examples of dose–response relationships pub-lished in the literature for ependymomas (2, 3).

The letter published in IJROBP that he responded to was specificallyaddressing the uncommon subtype “myxopapillary ependymomas” (4).Myxopapillary ependymomas are distinct from other ependymomas intheir histologic appearance and behavior. Myxopapillary ependymomas areuniformly low-grade tumors found in the cauda equina region, where mostarise from the filum terminale. The most characteristic histologic feature isthe abundance of intercellular and perivascular mucin. Myxopapillaryependymomas have a significantly better prognosis than other ependymo-mas. The 5-year survival rate was 100% for patients with myxopapillaryependymomas as compared to 76% for those with other ependymomas( p � 0.02) (5). Myxopapillary ependymomas are quite rare, and in our1998 series, they made up only 12 of the 80 (15%) total ependymomas and12 of the 19 (63%) ependymomas occurring in the lumbar spine. Thereseemed to be an association between local control and dose for patientswith myxopapillary ependymomas. The 5-year local control rates were100% with doses exceeding 50 Gy and 67% with lesser doses (p � 0.08,log-rank test). Unfortunately, because myxopapillary ependymomas arequite rare, there may be no other dose–response data available in theliterature for this histologic variant of ependymoma.

STEVEN SCHILD, M.D.WILLIAM WONG, M.D.KURT NISI, M.D.Department of Radiation OncologyMayo ClinicScottsdale, AZ

PII S0360-3016(02)03860-9

1. Kopelson G, Linggood RM, Kleinman GM, et al. Management ofintramedullary spinal cord tumors. Radiology 1980;135:473–479.

2. Garrett PG, Simpson WJ. Ependymomas: Results of radiation treat-ment. Int J Radiat Oncol Biol Phys 1983;9:1121–1124.

3. Stuben G, Stuschke M, Kroll M, et al. Postoperative radio-therapy ofspinal and intracranial ependymomas: Analysis of prognostic factors.Radiother Oncol 1997;45:3–10.

4. Schild SE, Wong W, Nisi K. In regard to the radiotherapy of myxo-papillary ependymomas. Int J Radiat Oncol Biol Phys 2002;53:787.

5. Schild SE, Nisi K, Scheithauer BW, et al. The results of radiotherapyfor ependymomas: The Mayo Clinic experience. Int J Radiat Oncol BiolPhys 1998;42(5):953–958.

282 I. J. Radiation Oncology ● Biology ● Physics Volume 55, Number 1, 2003