1094
I. J. Radiation Oncology 0 Biology 0 Physics
from participating in the response. Glial cells also may be important in the development of the less severe lesions. Radiation lesions are not always restricted to the white matter in our or in other studies (I) and the relative sparing of the gray matter may be because it is more heavily vascularized (2, 3). The absence of observation of vascular lesions in the presence of white matter necrosis is not evidence that it is absent. Further support for a vascular etiology is the reduction of radiation damage by vasoactive drugs (I). We feel that descriptions of lesions following spinal cord irradiation in animal models are important as reports of late radiation damage in humans are confounded by variations in dose, time after irradiation and use of chemotherapy. Large animals are especially useful as they can be observed for longer times after irradiation, electrophysiologic monitoring can be done, and volume studies can be more meaningfully related to humans. Important aspects of spinal cord radiation pathogenesis are yet to be elucidated, such as the role ofglial cells and cytokines in interacting with the vascular response. With a better understanding of pathogenesis, studies can be designed to alter the radiation response and reduce or prevent the consequences of late spinal cord radiation injury. POWERS, D.V.M., PH.D. EDWARD L. GILLETTE,D.V.M., PH.D. DANIEL H. GOULD, D.V.M., PH.D. Department of Radiological Health Sciences
BARBARAE.
and Pathology
Colorado State University Fort Collins, CO 80523 Hornsey, S.; Myers, R.; Jenkenson, T. The reduction of radiation damage to the spinal cord by post-irradiation administration of vasoactive drugs. Int. J. Radiat. Oncol. Biol. Phys. 18:1437-1442; 1990. Mildenberger, M.; Beth, T. G.; McGeer, E. G.; Ludgate, C. M. An animal model of prophylactic cranial irradiation: Histologic effects at acute, early and delayed stages. Int. J. Radiat. Oncol. Biol. Phys. l&1052-1060;1990. Valk, P. E.; Dillon, W. P. Radiation injury of the brain. AJR 156: 689-706;1991.
COMPARISON OF “ORTHOVOLTAGE” X-RAY VERSUS “MEGAVOLTAGE” ELECTRONS IN TREATING TUMORS NEAR THE EYE TV the Editor: In a recent issue, Amdur et ~11. (I) in “Radiation Therapy for Skin Cancer Near the Eye: Kilovoltage X-rays Versus Electrons” presented the results of the comparison between 250 kVp x-rays and 620 MeV electron beams in the treatment of skin cancers near the eye. This very nice piece of work presented an extremely pragmatic investigation of some old, tried and true technology versus the shiny, new and increasingly prevalent technology. As radiation oncologists see fewer and fewer cases of skin cancer, trainees will have less and less experience to rely upon in making decisions regarding treatment. The article set out a clear comparison between these methods and clearly demonstrates the circumstances in which the low energy x-rays provide advantages over electrons. In the process, the characteristics of radiation beams that need to be considered in applying them about the eye were reviewed. Any radiation oncologist wishing to treat tumors near the eye can benefit from this review. Additionally, the authors presented their own patient expense analysis. Although this is a bit different from institution to institution, it illustrates the advantages of having low energy x-rays available in a well-equipped department. The elegant investigation herein presented concludes that a careful comparison of the advantages and disadvantages argue in favor of kilovoltage x-rays for early stage skin cancer near the eye. JOHN D. EARLE, M.D.
William H. Donner Professor Mayo Medical School Rochester, MN 55905 1. Amdur, R. J.; Kalbaugh, K. J.; Ewald, L. M.; Parsons, J. T.; Mendenhall, W. M.; Bova, F. J.; Million, R. R. Radiation therapy for
Volume 23, Number 5, 1992 skin cancer near the eye: Kilovoltage x-rays Versus Electrons. Int. J. Radiat. Oncol. Biol. Phys. 23(4):769-779;1992. THE OUTCOME OF DEFINITIVE RADIOTHERAPY LOCALIZED PROSTATE CARCINOMA
FOR
Tu the Editor: Over the last year, three papers have appeared in the IJROBP on the significance of The Overall Treatment Time on the outcome of definitive radiotherapy for localized prostate cancer (I, 4, 5). The papers were interesting! They, however, assume an even greater importance when a radiobiologist analyzes the clinical data in an IJROBP editorial (2). Before we calculate the LI values, the cell cycle time, the growth fraction, the potential doubling time, the hypoxic component, T pot etc., of prostate cancer, it would help to look at some fundamental clinical aspects of this disease. From age-matched population studies of US males, about 40% of patients with prostate cancer die from natural causes within 10 years following treatment. Other studies have shown that 30-60% of patientsdepending on the stage-will develop and die from hematogenous metastases within 5 years following therapy. In both these categories, the primary tumor is considered “locally controlled.” Random biopsies of the prostate following radiation for cancer are positive in 15-20% of cases. Most of these cases do not recur locally on follow-up and are rarely the cause of death. Thus, the clinical significance of these findings is uncertain, but these tumors are also considered “locally controlled”. However, a recent paper suggests the most significant risk factor for hematogenous metastases in prostate cancer is local failure, only to be followed by stage and grade (3). In the paper by Lai et nl. (5), the study analyzed patients entered into RTOG studies 75-06 and 77-06. The authors grouped these patients together for the analyses ofthe effect of overall treatment time. However, patients entered into protocol 75-06 were those with a very high risk of nodal disease- advanced stage prostate cancer or positive nodes on lymphogram or histology if the primary was T I b and T2. Patients entered into 77-06 were patients with negative nodes by lymphogram or staging laparotomy. The patients in the two protocols thus had cancer of the prostate with very different clinical behavior patterns and survival rates. With all these variables and unknowns, radiation oncologists may be prudent to stay with the widely tested and accepted Time, Dose and Fractionation regimes for cancer of the prostate rather than settle for a radiobiological model of a “prostate cancer cell.” For early stage prostate cancer, state-of-the-art conventional radiation has produced excellent local tumor control and survival rates. GILBERTA. LAWRENCE,M.D. JEROMED. DERDEL, M.D. DOUGLAS COLKITT, M.D.
Life Care Cancer Center RD I, Sandy Lake Road Stoneboro, PA I6 I53 Amdur, R. J.; Parsons, J. T.: Fitzgerald, L. T.; Million, R. R. The effects of overall treatment time on local control in patients with adenocarcinoma of the prostate treated with radiation therapy. Int. J. Radiat. Oncol. Biol. Phys. 19:1377-1381;1990. Fowler, J. F. The effect of overall treatment time in radiotherapy for localized prostate cancer. Int. J. Radiat. Oncol. Biol. Phys. 21: lO97-1098;1991. Fuks, Z.: Leibel, S. A.; Wallner, K. E.; Colin, B. B.; Fair, W. R. Anderson, L. L.; Hilaris, B. S. Whitmore, W. F. The effect of local control on metastatic dissemination in carcinoma of the prostate: Long-term results in patients treated with I I25 implantation. Int. J. Radiat. Oncol. Biol. Phys. 2 I :S37-547; 199 I. Lai, P. P.; Perez, C. A.; Shapiro, S. J. Locket& M. A. Carcinoma of the prostate stage B and C: Lack of influence of duration of radiotherapy on tumor control and treatment morbidity. Int. J. Radiat. Oncol. Biol. Phys. 19:561-568;1990. Lai, P. P.; Pilepich, M. V. Krall, J. M.; Asbell, S. 0.; Hanks, G. E.; Perez, P. A.; Rubin, P. Sause, W. T.; Cox, J. D. The effect of overall treatment time on the outcome ofdefinitive radiotherapy for localized prostate carcinoma. The Radiation Therapy Oncology Group 7506 and 77-06 experience. Int. J. Radiat. Oncol. Biol. Phys. 2 1:925933:1991.
I. J. Radiation Oncology 0 Biology 0 Physics
from participating in the response. Glial cells also may be important in the development of the less severe lesions. Radiation lesions are not always restricted to the white matter in our or in other studies (I) and the relative sparing of the gray matter may be because it is more heavily vascularized (2, 3). The absence of observation of vascular lesions in the presence of white matter necrosis is not evidence that it is absent. Further support for a vascular etiology is the reduction of radiation damage by vasoactive drugs (I). We feel that descriptions of lesions following spinal cord irradiation in animal models are important as reports of late radiation damage in humans are confounded by variations in dose, time after irradiation and use of chemotherapy. Large animals are especially useful as they can be observed for longer times after irradiation, electrophysiologic monitoring can be done, and volume studies can be more meaningfully related to humans. Important aspects of spinal cord radiation pathogenesis are yet to be elucidated, such as the role ofglial cells and cytokines in interacting with the vascular response. With a better understanding of pathogenesis, studies can be designed to alter the radiation response and reduce or prevent the consequences of late spinal cord radiation injury. POWERS, D.V.M., PH.D. EDWARD L. GILLETTE,D.V.M., PH.D. DANIEL H. GOULD, D.V.M., PH.D. Department of Radiological Health Sciences
BARBARAE.
and Pathology
Colorado State University Fort Collins, CO 80523 Hornsey, S.; Myers, R.; Jenkenson, T. The reduction of radiation damage to the spinal cord by post-irradiation administration of vasoactive drugs. Int. J. Radiat. Oncol. Biol. Phys. 18:1437-1442; 1990. Mildenberger, M.; Beth, T. G.; McGeer, E. G.; Ludgate, C. M. An animal model of prophylactic cranial irradiation: Histologic effects at acute, early and delayed stages. Int. J. Radiat. Oncol. Biol. Phys. l&1052-1060;1990. Valk, P. E.; Dillon, W. P. Radiation injury of the brain. AJR 156: 689-706;1991.
COMPARISON OF “ORTHOVOLTAGE” X-RAY VERSUS “MEGAVOLTAGE” ELECTRONS IN TREATING TUMORS NEAR THE EYE TV the Editor: In a recent issue, Amdur et ~11. (I) in “Radiation Therapy for Skin Cancer Near the Eye: Kilovoltage X-rays Versus Electrons” presented the results of the comparison between 250 kVp x-rays and 620 MeV electron beams in the treatment of skin cancers near the eye. This very nice piece of work presented an extremely pragmatic investigation of some old, tried and true technology versus the shiny, new and increasingly prevalent technology. As radiation oncologists see fewer and fewer cases of skin cancer, trainees will have less and less experience to rely upon in making decisions regarding treatment. The article set out a clear comparison between these methods and clearly demonstrates the circumstances in which the low energy x-rays provide advantages over electrons. In the process, the characteristics of radiation beams that need to be considered in applying them about the eye were reviewed. Any radiation oncologist wishing to treat tumors near the eye can benefit from this review. Additionally, the authors presented their own patient expense analysis. Although this is a bit different from institution to institution, it illustrates the advantages of having low energy x-rays available in a well-equipped department. The elegant investigation herein presented concludes that a careful comparison of the advantages and disadvantages argue in favor of kilovoltage x-rays for early stage skin cancer near the eye. JOHN D. EARLE, M.D.
William H. Donner Professor Mayo Medical School Rochester, MN 55905 1. Amdur, R. J.; Kalbaugh, K. J.; Ewald, L. M.; Parsons, J. T.; Mendenhall, W. M.; Bova, F. J.; Million, R. R. Radiation therapy for
Volume 23, Number 5, 1992 skin cancer near the eye: Kilovoltage x-rays Versus Electrons. Int. J. Radiat. Oncol. Biol. Phys. 23(4):769-779;1992. THE OUTCOME OF DEFINITIVE RADIOTHERAPY LOCALIZED PROSTATE CARCINOMA
FOR
Tu the Editor: Over the last year, three papers have appeared in the IJROBP on the significance of The Overall Treatment Time on the outcome of definitive radiotherapy for localized prostate cancer (I, 4, 5). The papers were interesting! They, however, assume an even greater importance when a radiobiologist analyzes the clinical data in an IJROBP editorial (2). Before we calculate the LI values, the cell cycle time, the growth fraction, the potential doubling time, the hypoxic component, T pot etc., of prostate cancer, it would help to look at some fundamental clinical aspects of this disease. From age-matched population studies of US males, about 40% of patients with prostate cancer die from natural causes within 10 years following treatment. Other studies have shown that 30-60% of patientsdepending on the stage-will develop and die from hematogenous metastases within 5 years following therapy. In both these categories, the primary tumor is considered “locally controlled.” Random biopsies of the prostate following radiation for cancer are positive in 15-20% of cases. Most of these cases do not recur locally on follow-up and are rarely the cause of death. Thus, the clinical significance of these findings is uncertain, but these tumors are also considered “locally controlled”. However, a recent paper suggests the most significant risk factor for hematogenous metastases in prostate cancer is local failure, only to be followed by stage and grade (3). In the paper by Lai et nl. (5), the study analyzed patients entered into RTOG studies 75-06 and 77-06. The authors grouped these patients together for the analyses ofthe effect of overall treatment time. However, patients entered into protocol 75-06 were those with a very high risk of nodal disease- advanced stage prostate cancer or positive nodes on lymphogram or histology if the primary was T I b and T2. Patients entered into 77-06 were patients with negative nodes by lymphogram or staging laparotomy. The patients in the two protocols thus had cancer of the prostate with very different clinical behavior patterns and survival rates. With all these variables and unknowns, radiation oncologists may be prudent to stay with the widely tested and accepted Time, Dose and Fractionation regimes for cancer of the prostate rather than settle for a radiobiological model of a “prostate cancer cell.” For early stage prostate cancer, state-of-the-art conventional radiation has produced excellent local tumor control and survival rates. GILBERTA. LAWRENCE,M.D. JEROMED. DERDEL, M.D. DOUGLAS COLKITT, M.D.
Life Care Cancer Center RD I, Sandy Lake Road Stoneboro, PA I6 I53 Amdur, R. J.; Parsons, J. T.: Fitzgerald, L. T.; Million, R. R. The effects of overall treatment time on local control in patients with adenocarcinoma of the prostate treated with radiation therapy. Int. J. Radiat. Oncol. Biol. Phys. 19:1377-1381;1990. Fowler, J. F. The effect of overall treatment time in radiotherapy for localized prostate cancer. Int. J. Radiat. Oncol. Biol. Phys. 21: lO97-1098;1991. Fuks, Z.: Leibel, S. A.; Wallner, K. E.; Colin, B. B.; Fair, W. R. Anderson, L. L.; Hilaris, B. S. Whitmore, W. F. The effect of local control on metastatic dissemination in carcinoma of the prostate: Long-term results in patients treated with I I25 implantation. Int. J. Radiat. Oncol. Biol. Phys. 2 I :S37-547; 199 I. Lai, P. P.; Perez, C. A.; Shapiro, S. J. Locket& M. A. Carcinoma of the prostate stage B and C: Lack of influence of duration of radiotherapy on tumor control and treatment morbidity. Int. J. Radiat. Oncol. Biol. Phys. 19:561-568;1990. Lai, P. P.; Pilepich, M. V. Krall, J. M.; Asbell, S. 0.; Hanks, G. E.; Perez, P. A.; Rubin, P. Sause, W. T.; Cox, J. D. The effect of overall treatment time on the outcome ofdefinitive radiotherapy for localized prostate carcinoma. The Radiation Therapy Oncology Group 7506 and 77-06 experience. Int. J. Radiat. Oncol. Biol. Phys. 2 1:925933:1991.
