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Cyberknife and Prostate Cancer. In Regard to King et al. (Int J Radiat Oncol Biol Phys 2009;73:1043–1048)
Int. J. Radiation Oncology Biol. Phys., Vol. 75, No. 2, pp. 632–636, 2009 Copyright Ó 2009 Elsevier Inc. Printed in the USA. All rights reserved 0360-3016/09/$–see front matter
LETTERS TO THE EDITOR RISKS OF RADIATION THERAPY IN PATIENTS WITH NEUROFIBROMATOSIS
5. Beyer RA, Paden P, Sobel DF, Flynn FG. Moyamoya pattern of vascular occlusion after radiotherapy for glioma of the optic chiasm. Neurology 1986;36:1173–1178. 6. Kortmann RD, Timmermann B, Taylor RE, et al. Current and future strategies in radiotherapy of childhood low-grade glioma of the brain. Part II: Treatment-related late toxicity. Strahlenther Onkol 2003;179:585–597.
To the Editor: In the article by Wentworth et al. (1), the authors analyze their experience with radiation therapy in the treatment of central and peripheral nervous system tumors in patients with neurofibromatosis (NF) Type 1 (NFI1) or Type 2 (NFI2). We share their concern about the therapeutic dilemma often encountered in the management of tumors in these patients. On one hand, tumor control can be achieved in more than 75% of cases, as mentioned in their article. On the other hand, these results need to be weighed against the higher rate of radiation-induced complications in this population. Wentworth et al. mention only in passing the risk of the malignant transformation of some tumors such as low-grade gliomas and plexiform neurofibromas after radiotherapy. Although the risk of spontaneous transformation exists in the absence of radiotherapy, it is rare in patients with pediatric low-grade gliomas (2) and plexiform neurofibromas. Radiotherapy, however, may increase this risk, as suggested by the two malignant transformations of low-grade gliomas reported in the study of Wentworth et al. Radiosurgery can be an attractive alternative to conventionally fractionated radiotherapy for alleviating the treatment burden in patients who request repeated procedures for multiple primaries. It is unclear to us, however, whether this mode of therapy reduces the risk of a second malignancy as well. Wentworth et al. also omit discussing data from the literature about the vascular complications of NF associated with radiotherapy, in particular the Moya-Moya syndrome in patients with lesions located close to the skull base. In our experience, the fractionated irradiation of optic pathway tumors in children with NF1 is associated with a fivefold increase in the rate of cerebral arteriopathies (11 of 37 patients with NF1 vs. 2 of 32 patients without NF1, p = 0.015) (3). In this study, the cumulative incidence of this type of complication in children with NF1 reached 30% with a median of 7 years’ follow-up. Other authors have had similar experiences, suggesting a peculiar sensitivity of blood vessels to therapeutic irradiation in patients with NF1 (4, 5). A safer approach now advocated by the European pediatric low-grade glioma consortium is to treat children with NF1 with chemotherapy, with radiotherapy reserved for those who fail chemotherapy (6). Close monitoring of the permeability of vessels in the radiation-involved fields is advocated in these settings. In conclusion, patients with NF1 still pose a formidable challenge to radiation oncologists. As far as tumor control goes, the paper by Wentworth et al. provides evidence regarding the valuable role of radiotherapy in the management of the disorder. As far as toxicity goes, however, the jury is still out.
CYBERKNIFE AND PROSTATE CANCER. IN REGARD TO KING ET AL. (INT J RADIAT ONCOL BIOL PHYS 2009;73:1043–1048) To the Editor: King et al. reported the results of a prospective Phase II clinical trial of an experimental treatment for patients with low-risk prostate cancer. However, they did not state what their a priori hypothesis was or how they determined how many patients must be subjected to this experimental treatment to determine whether this treatment was safe and promising enough to be tested in a Phase III trial. They also stated that an interim analysis was planned but provided no information about any early stopping rules or the maximal number of adverse events or failures that would trigger premature termination of the trial. Many safe and highly effective treatment options are available to patients with low-risk prostate cancer (1, 2); therefore, it is important for the reader to be provided with the above details to demonstrate that their study was conducted in an ethical manner and did not subject the patients to unreasonable risk. BHADRASAIN VIKRAM, M.D. Clinical Radiation Oncology Branch National Cancer Institute Rockville, MD Disclaimer: The opinions expressed are those of the author and do not necessarily represent the views of the National Institutes of Health or the Department of Health and Human Services. doi:10.1016/j.ijrobp.2009.05.064 1. Lawton CA, DeSilvio M, Lee WR, et al. Results of a phase II trial of transrectal ultrasound-guided permanent radioactive implantation of the prostate for definitive management of localized adenocarcinoma of the prostate (Radiation Therapy Oncology Group 98-05). Int J Radiat Oncol Biol Phys 2007;67:39–47. 2. D’Amico AV, Whittington R, Malkowicz SB, et al. Biochemical outcome after radical prostatectomy, external beam radiation therapy, or interstitial radiation therapy for clinically localized prostate cancer. JAMA 1998;280: 969–974.
JACQUES GRILL, M.D., PH.D. Brain Tumor Program Department of Pediatric and Adolescent Oncology Department of Radiation Oncology Gustave Roussy Cancer Institute Villejuif, France
EVALUATING GASTROSTOMY FEEDING ON DAILY SETUP VARIATIONS AND PLANNING MARGINS IN HEAD-AND-NECK RADIOTHERAPY
FREDERIC DHERMAIN, M.D. JEAN-LOUIS HABRAND, M.D. Department of Radiation Oncology Gustave Roussy Cancer Institute Villejuif, France
To the Editor: We would like to highlight our pilot work evaluating the effect of weight loss on setup variations and the planning target volume (PTV) in head-and-neck (H&N) radiotherapy (RT). To our knowledge, no published study has assessed the effects of weight changes on RT margins. Our prospective case-control study recruited 20 H&N patients—10 with a percutaneous endoscopic gastrostomy (PEG) tube inserted before RT and 10 without. The criteria for PEG insertion included pre-existing dysphagia, compromised dietary intake resulting in $10% weight loss before RT, concurrent chemotherapy, and bilateral neck RT. Electronic portal images provided daily verification and recording of the setup variations. The PTV margins were derived from the calculated systematic and random errors. The clinical parameters of both groups were balanced with respect to age, gender, tumor site, smoking status, and alcohol consumption. A significant difference was found in weight loss between the two groups, with the PEG group losing an average 2.6 kg less than the non-PEG group (p = .04). This resulted in a reduction of the setup variation for the PEG patients in the superoinferior and anteroposterior planes. The resultant PTV margin in
doi:10.1016/j.ijrobp.2009.03.076 1. Wentworth S, Pinn M, Bourland JD, et al. Clinical experience with radiation therapy in the management of neurofibromatosis-associated central nervous system tumors. Int J Radiat Oncol Biol Phys 2009;73: 208–213. 2. Broniscer A, Baker SJ, West AN, et al. Clinical and molecular characteristics of malignant transformation of low-grade glioma in children. J Clin Oncol 2007;25:682–689. 3. Grill J, Couanet D, Cappelli C, et al. Radiation-induced cerebral vasculopathy in children with neurofibromatosis and optic pathway glioma. Ann Neurol 1999;45:393–396. 4. Kestle JRW, Hoffman HJ, Mock AR. Moyamoya phenomenon after radiation for optic glioma. J Neurosurg 1993;79:32–35. 632
LETTERS TO THE EDITOR RISKS OF RADIATION THERAPY IN PATIENTS WITH NEUROFIBROMATOSIS
5. Beyer RA, Paden P, Sobel DF, Flynn FG. Moyamoya pattern of vascular occlusion after radiotherapy for glioma of the optic chiasm. Neurology 1986;36:1173–1178. 6. Kortmann RD, Timmermann B, Taylor RE, et al. Current and future strategies in radiotherapy of childhood low-grade glioma of the brain. Part II: Treatment-related late toxicity. Strahlenther Onkol 2003;179:585–597.
To the Editor: In the article by Wentworth et al. (1), the authors analyze their experience with radiation therapy in the treatment of central and peripheral nervous system tumors in patients with neurofibromatosis (NF) Type 1 (NFI1) or Type 2 (NFI2). We share their concern about the therapeutic dilemma often encountered in the management of tumors in these patients. On one hand, tumor control can be achieved in more than 75% of cases, as mentioned in their article. On the other hand, these results need to be weighed against the higher rate of radiation-induced complications in this population. Wentworth et al. mention only in passing the risk of the malignant transformation of some tumors such as low-grade gliomas and plexiform neurofibromas after radiotherapy. Although the risk of spontaneous transformation exists in the absence of radiotherapy, it is rare in patients with pediatric low-grade gliomas (2) and plexiform neurofibromas. Radiotherapy, however, may increase this risk, as suggested by the two malignant transformations of low-grade gliomas reported in the study of Wentworth et al. Radiosurgery can be an attractive alternative to conventionally fractionated radiotherapy for alleviating the treatment burden in patients who request repeated procedures for multiple primaries. It is unclear to us, however, whether this mode of therapy reduces the risk of a second malignancy as well. Wentworth et al. also omit discussing data from the literature about the vascular complications of NF associated with radiotherapy, in particular the Moya-Moya syndrome in patients with lesions located close to the skull base. In our experience, the fractionated irradiation of optic pathway tumors in children with NF1 is associated with a fivefold increase in the rate of cerebral arteriopathies (11 of 37 patients with NF1 vs. 2 of 32 patients without NF1, p = 0.015) (3). In this study, the cumulative incidence of this type of complication in children with NF1 reached 30% with a median of 7 years’ follow-up. Other authors have had similar experiences, suggesting a peculiar sensitivity of blood vessels to therapeutic irradiation in patients with NF1 (4, 5). A safer approach now advocated by the European pediatric low-grade glioma consortium is to treat children with NF1 with chemotherapy, with radiotherapy reserved for those who fail chemotherapy (6). Close monitoring of the permeability of vessels in the radiation-involved fields is advocated in these settings. In conclusion, patients with NF1 still pose a formidable challenge to radiation oncologists. As far as tumor control goes, the paper by Wentworth et al. provides evidence regarding the valuable role of radiotherapy in the management of the disorder. As far as toxicity goes, however, the jury is still out.
CYBERKNIFE AND PROSTATE CANCER. IN REGARD TO KING ET AL. (INT J RADIAT ONCOL BIOL PHYS 2009;73:1043–1048) To the Editor: King et al. reported the results of a prospective Phase II clinical trial of an experimental treatment for patients with low-risk prostate cancer. However, they did not state what their a priori hypothesis was or how they determined how many patients must be subjected to this experimental treatment to determine whether this treatment was safe and promising enough to be tested in a Phase III trial. They also stated that an interim analysis was planned but provided no information about any early stopping rules or the maximal number of adverse events or failures that would trigger premature termination of the trial. Many safe and highly effective treatment options are available to patients with low-risk prostate cancer (1, 2); therefore, it is important for the reader to be provided with the above details to demonstrate that their study was conducted in an ethical manner and did not subject the patients to unreasonable risk. BHADRASAIN VIKRAM, M.D. Clinical Radiation Oncology Branch National Cancer Institute Rockville, MD Disclaimer: The opinions expressed are those of the author and do not necessarily represent the views of the National Institutes of Health or the Department of Health and Human Services. doi:10.1016/j.ijrobp.2009.05.064 1. Lawton CA, DeSilvio M, Lee WR, et al. Results of a phase II trial of transrectal ultrasound-guided permanent radioactive implantation of the prostate for definitive management of localized adenocarcinoma of the prostate (Radiation Therapy Oncology Group 98-05). Int J Radiat Oncol Biol Phys 2007;67:39–47. 2. D’Amico AV, Whittington R, Malkowicz SB, et al. Biochemical outcome after radical prostatectomy, external beam radiation therapy, or interstitial radiation therapy for clinically localized prostate cancer. JAMA 1998;280: 969–974.
JACQUES GRILL, M.D., PH.D. Brain Tumor Program Department of Pediatric and Adolescent Oncology Department of Radiation Oncology Gustave Roussy Cancer Institute Villejuif, France
EVALUATING GASTROSTOMY FEEDING ON DAILY SETUP VARIATIONS AND PLANNING MARGINS IN HEAD-AND-NECK RADIOTHERAPY
FREDERIC DHERMAIN, M.D. JEAN-LOUIS HABRAND, M.D. Department of Radiation Oncology Gustave Roussy Cancer Institute Villejuif, France
To the Editor: We would like to highlight our pilot work evaluating the effect of weight loss on setup variations and the planning target volume (PTV) in head-and-neck (H&N) radiotherapy (RT). To our knowledge, no published study has assessed the effects of weight changes on RT margins. Our prospective case-control study recruited 20 H&N patients—10 with a percutaneous endoscopic gastrostomy (PEG) tube inserted before RT and 10 without. The criteria for PEG insertion included pre-existing dysphagia, compromised dietary intake resulting in $10% weight loss before RT, concurrent chemotherapy, and bilateral neck RT. Electronic portal images provided daily verification and recording of the setup variations. The PTV margins were derived from the calculated systematic and random errors. The clinical parameters of both groups were balanced with respect to age, gender, tumor site, smoking status, and alcohol consumption. A significant difference was found in weight loss between the two groups, with the PEG group losing an average 2.6 kg less than the non-PEG group (p = .04). This resulted in a reduction of the setup variation for the PEG patients in the superoinferior and anteroposterior planes. The resultant PTV margin in
doi:10.1016/j.ijrobp.2009.03.076 1. Wentworth S, Pinn M, Bourland JD, et al. Clinical experience with radiation therapy in the management of neurofibromatosis-associated central nervous system tumors. Int J Radiat Oncol Biol Phys 2009;73: 208–213. 2. Broniscer A, Baker SJ, West AN, et al. Clinical and molecular characteristics of malignant transformation of low-grade glioma in children. J Clin Oncol 2007;25:682–689. 3. Grill J, Couanet D, Cappelli C, et al. Radiation-induced cerebral vasculopathy in children with neurofibromatosis and optic pathway glioma. Ann Neurol 1999;45:393–396. 4. Kestle JRW, Hoffman HJ, Mock AR. Moyamoya phenomenon after radiation for optic glioma. J Neurosurg 1993;79:32–35. 632