VOLUME
32
䡠
NUMBER
30
䡠
OCTOBER
20
2014
JOURNAL OF CLINICAL ONCOLOGY
C O R R E S P O N D E N C E
Stereotactic Body Radiation Therapy Is a Cost-Effective Alternative to Intensity-Modulated Radiation Therapy TO THE EDITOR: We would like to congratulate Yu et al1 for an informative and unique article regarding the comparison of toxicities between intensity-modulated radiation therapy (IMRT) versus stereotactic body radiation therapy (SBRT) for prostate cancer. The authors conclude that SBRT is less costly but may incur quality of life changes. The applicability of SBRT for prostate cancer is relatively new. We are still learning about the doses used in SBRT, critical organ dosimetry, and its radiobiological effects. As a consequence of limited experience with this technique, physicians may have a lower threshold for ordering diagnostic testing when there are signs of potential genitourinary (GU) –related adverse effects. This, in turn, may lead to an overestimation of GU toxicities in the Yu et al study.1 Secondly, the authors admit that SBRT delivery has improved through the years. Their analysis includes patients who were treated during a time when dose constraints to organs at risk such as the urethra were not routinely accounted for.1 Anthony D’Amico, MD, PhD, in his accompanying editorial, suggests that SBRT for prostate cancer should be performed in the context of a clinical trial in which outcomes and toxicities can be carefully studied.2 At the University of Pittsburgh Cancer Center, there is a trial assessing the use of SBRT for low- and intermediate-risk prostate cancer. The trial is designed such that each patient receives a computed tomography simulation with intravenous contrast (Foley catheter in place with contrast), along with a pelvic magnetic resonance imaging. These two imaging modalities are registered for treatment planning, and the membranous and prostatic urethra is accurately delineated to limit dose during planning. With this novel technique, we have observed little acute and subacute toxicities. Long-term toxicity data are pending. Recently, Loblaw et al3 published their series of prostate SBRT and used a technique that did not limit dose to the urethra. Despite this, both acute and long-term grade ⱖ 3 GU toxicities were only 1%. We expect
that our results are at the very least similar given that we have taken the precaution to limit dose to the urethra. We do have one question for the authors. In the construction of variables, “patients were assigned to the IMRT group if there were four or more codes for IMRT treatment delivery or if they had the IMRT treatment code in addition to four or more generic external beam delivery codes.” Because a standard course of IMRT typically includes ⬎ 35 fractions, we wonder what proportion of patients in the IMRT group did not complete the treatment course. Would the rates of GU toxicity differ if a comparison of those who completed IMRT and those who completed SBRT were performed? We agree with Yu et al that SBRT of the prostate should not be used outside of a well-designed clinical trial.1 This technique offers much potential benefit, including but not limited to, convenience to the patient, and theoretically improved radiobiologic effectiveness if used properly. Patients should be informed of all available options, and it is the physician’s duty to keep a balanced level of caution and open-mindedness, given the available evidence, or we could be doing a disfavor for well-suited patients who could potentially benefit from this technique.
Kimmen Quan, Malolan S. Rajagopalan, and Dwight E. Heron University of Pittsburgh Cancer Institute, Pittsburgh, PA
AUTHORS’ DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST
The author(s) indicated no potential conflicts of interest. REFERENCES 1. Yu JB, Cramer LD, Herrin J, et al: Stereotactic body radiation therapy versus intensity-modulated radiation therapy for prostate cancer: Comparison of toxicity. J Clin Oncol 32:1195-1201, 2014 2. D’Amico AV: Stereotactic body radiation therapy versus intensity-modulated radiation therapy for prostate cancer: Less cost at the expense of more genitourinary toxicity is a concerning but testable hypothesis. J Clin Oncol 32:1183-1185, 2014 3. Loblaw A, Cheung P, D’Alimonte L, et al: Prostate stereotactic ablative body radiotherapy using a linear accelerator: Toxicity, biochemical, and pathological outcomes. Radiat Oncol 107:153-158, 2013
DOI: 10.1200/JCO.2014.56.6737; published online ahead of print at www.jco.org on September 2, 2014
■ ■ ■
Journal of Clinical Oncology, Vol 32, No 30 (October 20), 2014: pp 3451
© 2014 by American Society of Clinical Oncology
Downloaded from jco.ascopubs.org on June 2, 2015. For personal use only. No other uses without permission. Copyright © 2014 American Society of Clinical Oncology. All rights reserved.
3451
32
䡠
NUMBER
30
䡠
OCTOBER
20
2014
JOURNAL OF CLINICAL ONCOLOGY
C O R R E S P O N D E N C E
Stereotactic Body Radiation Therapy Is a Cost-Effective Alternative to Intensity-Modulated Radiation Therapy TO THE EDITOR: We would like to congratulate Yu et al1 for an informative and unique article regarding the comparison of toxicities between intensity-modulated radiation therapy (IMRT) versus stereotactic body radiation therapy (SBRT) for prostate cancer. The authors conclude that SBRT is less costly but may incur quality of life changes. The applicability of SBRT for prostate cancer is relatively new. We are still learning about the doses used in SBRT, critical organ dosimetry, and its radiobiological effects. As a consequence of limited experience with this technique, physicians may have a lower threshold for ordering diagnostic testing when there are signs of potential genitourinary (GU) –related adverse effects. This, in turn, may lead to an overestimation of GU toxicities in the Yu et al study.1 Secondly, the authors admit that SBRT delivery has improved through the years. Their analysis includes patients who were treated during a time when dose constraints to organs at risk such as the urethra were not routinely accounted for.1 Anthony D’Amico, MD, PhD, in his accompanying editorial, suggests that SBRT for prostate cancer should be performed in the context of a clinical trial in which outcomes and toxicities can be carefully studied.2 At the University of Pittsburgh Cancer Center, there is a trial assessing the use of SBRT for low- and intermediate-risk prostate cancer. The trial is designed such that each patient receives a computed tomography simulation with intravenous contrast (Foley catheter in place with contrast), along with a pelvic magnetic resonance imaging. These two imaging modalities are registered for treatment planning, and the membranous and prostatic urethra is accurately delineated to limit dose during planning. With this novel technique, we have observed little acute and subacute toxicities. Long-term toxicity data are pending. Recently, Loblaw et al3 published their series of prostate SBRT and used a technique that did not limit dose to the urethra. Despite this, both acute and long-term grade ⱖ 3 GU toxicities were only 1%. We expect
that our results are at the very least similar given that we have taken the precaution to limit dose to the urethra. We do have one question for the authors. In the construction of variables, “patients were assigned to the IMRT group if there were four or more codes for IMRT treatment delivery or if they had the IMRT treatment code in addition to four or more generic external beam delivery codes.” Because a standard course of IMRT typically includes ⬎ 35 fractions, we wonder what proportion of patients in the IMRT group did not complete the treatment course. Would the rates of GU toxicity differ if a comparison of those who completed IMRT and those who completed SBRT were performed? We agree with Yu et al that SBRT of the prostate should not be used outside of a well-designed clinical trial.1 This technique offers much potential benefit, including but not limited to, convenience to the patient, and theoretically improved radiobiologic effectiveness if used properly. Patients should be informed of all available options, and it is the physician’s duty to keep a balanced level of caution and open-mindedness, given the available evidence, or we could be doing a disfavor for well-suited patients who could potentially benefit from this technique.
Kimmen Quan, Malolan S. Rajagopalan, and Dwight E. Heron University of Pittsburgh Cancer Institute, Pittsburgh, PA
AUTHORS’ DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST
The author(s) indicated no potential conflicts of interest. REFERENCES 1. Yu JB, Cramer LD, Herrin J, et al: Stereotactic body radiation therapy versus intensity-modulated radiation therapy for prostate cancer: Comparison of toxicity. J Clin Oncol 32:1195-1201, 2014 2. D’Amico AV: Stereotactic body radiation therapy versus intensity-modulated radiation therapy for prostate cancer: Less cost at the expense of more genitourinary toxicity is a concerning but testable hypothesis. J Clin Oncol 32:1183-1185, 2014 3. Loblaw A, Cheung P, D’Alimonte L, et al: Prostate stereotactic ablative body radiotherapy using a linear accelerator: Toxicity, biochemical, and pathological outcomes. Radiat Oncol 107:153-158, 2013
DOI: 10.1200/JCO.2014.56.6737; published online ahead of print at www.jco.org on September 2, 2014
■ ■ ■
Journal of Clinical Oncology, Vol 32, No 30 (October 20), 2014: pp 3451
© 2014 by American Society of Clinical Oncology
Downloaded from jco.ascopubs.org on June 2, 2015. For personal use only. No other uses without permission. Copyright © 2014 American Society of Clinical Oncology. All rights reserved.
3451
