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85 Brachytherapy is superior to conformal external beam therapy in the treatment of prostate cancer
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Wednesday, 31 January 2001
Debate B R A C H Y T H E R A P Y IS S U P E R I O R TO C O N F O R M A L E X T E R N A L B E A M T H E R A P Y IN THE T R E A T M E N T OF LOCALISED PROSTATE CANCER 85
Brachytherapy is superior to conformal external beam therapy in the treatment of prostate cancer G. Duchesne The Alfred Hospital, Radiation Onco/ogy, Me~bourne,Australia Purpose : To evaluate the relative efficacy of brachytherapy in the management of Iocalised prostate cancer. Methods: Biological, physical and technical aspects of prostate brachytherapy are reviewed, together with treatment outcome and morbidity data. Results: Hypofractionated high dose rate (HDR) temporary brachytherapy exploits the vulnerability of slowly proliferating cells (such as prostate cancer) to increased fraction size. Biologically effective doses (BED) equivalent to 90 Gy external beam irradiation are achieved within the target, while the rapid dose fall-off around the implant provides physical and biological protection of the surrounding normal tissues. Recommended prescribed doses for low dose rate (LDR) implants are 145 Gy for 1-125 and 115 Gy for Pd-103; the extremely low energy of the emissions together with the dose fall-off ensure maximal rectal sparing. In addition the RBE factors (respectively 1.4 and 1.9) may contribute to greater cell kill than that inflicted by external beam photons. LDR implant is particularly suited to early stage disease (low-risk). The technique of real-time image-guided implantation ensures the ultimate conformal treatment of the target whilst avoiding surrounding tissues, and avoids the day-to day variation inherent in conformal external beam irradiation. Early results of HDR boost therapy suggest 5 year biochemical progression-free survival rates of 80% or more, in patients with up to T3 disease, with morb!dity rates somewhat less than with conventional external beam treatment. Published series of LDR patients suggest biochemical control rates of 80-90% at 7 years (low risk), with minimal long-term morbidity, particularly with potency preservation. Patient quality of life issues are being addressed, but patient convenience is greater for brachytherapy than for conformal external beam irradiation. Conclusion: Modern prostate brachytherapy is superior radiobiologically, physically, technically and in convenience to conformal high dose radiation, with excellent progression-free outcomes and morbidity profile. 86
Brachytherapy is superior to external beam in localized prostate cancer: the case against. A. Zietman Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Bostonm MA 02114 The treatment of localized prostate cancer by brachytherapy is an interesting area of experimentation the true potentiel of which is currently unknown. None of the available data in its favor rises above the second from lowest enthusiasm for this collection of techniques (high-dose rate, low-dose rate, as mono-therapy, or as a boost) there is a risk of turning away from the most trusted radiation therapy avairable, external beam. The case for external beam over .brachytherapy remains strong and rests on several pillars: 1. Long-term bNED rates compalable to brachytherapy series but supported by larger numbers of patients from multiple major institutions. 2. Recent documented improvements in techniques and outcome that derive from the use of contormal, high-dose therapy. 3. National studies that document equivalent outcomes in community and academic centers. 4, The low morbidity of conformal external beam as compared with the potentially high morbidity of low-dose rate brachytherapy and the unknown morbidity of high-dose rate brachytherapy. 5, Uncertainty about the radiobiology of brachytherapy and the alpha/beta ratio of prostate cancer makes for inconsistency between the protagonists of high- and low dose-rate therapy.
6. The low cost of conformal external beam as compared to combinations of brachytherapy and external. 7. Quality assurance issues in brachytherapy in which the learning curve is long and physicians not trained in radiation oncology are frequently performing the technique. Brachytherapy shows promise but we should not lose sight of the many real concerns about its widespread implementation.
Wednesday, 31 January 2001
Debate B R A C H Y T H E R A P Y IS S U P E R I O R TO C O N F O R M A L E X T E R N A L B E A M T H E R A P Y IN THE T R E A T M E N T OF LOCALISED PROSTATE CANCER 85
Brachytherapy is superior to conformal external beam therapy in the treatment of prostate cancer G. Duchesne The Alfred Hospital, Radiation Onco/ogy, Me~bourne,Australia Purpose : To evaluate the relative efficacy of brachytherapy in the management of Iocalised prostate cancer. Methods: Biological, physical and technical aspects of prostate brachytherapy are reviewed, together with treatment outcome and morbidity data. Results: Hypofractionated high dose rate (HDR) temporary brachytherapy exploits the vulnerability of slowly proliferating cells (such as prostate cancer) to increased fraction size. Biologically effective doses (BED) equivalent to 90 Gy external beam irradiation are achieved within the target, while the rapid dose fall-off around the implant provides physical and biological protection of the surrounding normal tissues. Recommended prescribed doses for low dose rate (LDR) implants are 145 Gy for 1-125 and 115 Gy for Pd-103; the extremely low energy of the emissions together with the dose fall-off ensure maximal rectal sparing. In addition the RBE factors (respectively 1.4 and 1.9) may contribute to greater cell kill than that inflicted by external beam photons. LDR implant is particularly suited to early stage disease (low-risk). The technique of real-time image-guided implantation ensures the ultimate conformal treatment of the target whilst avoiding surrounding tissues, and avoids the day-to day variation inherent in conformal external beam irradiation. Early results of HDR boost therapy suggest 5 year biochemical progression-free survival rates of 80% or more, in patients with up to T3 disease, with morb!dity rates somewhat less than with conventional external beam treatment. Published series of LDR patients suggest biochemical control rates of 80-90% at 7 years (low risk), with minimal long-term morbidity, particularly with potency preservation. Patient quality of life issues are being addressed, but patient convenience is greater for brachytherapy than for conformal external beam irradiation. Conclusion: Modern prostate brachytherapy is superior radiobiologically, physically, technically and in convenience to conformal high dose radiation, with excellent progression-free outcomes and morbidity profile. 86
Brachytherapy is superior to external beam in localized prostate cancer: the case against. A. Zietman Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Bostonm MA 02114 The treatment of localized prostate cancer by brachytherapy is an interesting area of experimentation the true potentiel of which is currently unknown. None of the available data in its favor rises above the second from lowest enthusiasm for this collection of techniques (high-dose rate, low-dose rate, as mono-therapy, or as a boost) there is a risk of turning away from the most trusted radiation therapy avairable, external beam. The case for external beam over .brachytherapy remains strong and rests on several pillars: 1. Long-term bNED rates compalable to brachytherapy series but supported by larger numbers of patients from multiple major institutions. 2. Recent documented improvements in techniques and outcome that derive from the use of contormal, high-dose therapy. 3. National studies that document equivalent outcomes in community and academic centers. 4, The low morbidity of conformal external beam as compared with the potentially high morbidity of low-dose rate brachytherapy and the unknown morbidity of high-dose rate brachytherapy. 5, Uncertainty about the radiobiology of brachytherapy and the alpha/beta ratio of prostate cancer makes for inconsistency between the protagonists of high- and low dose-rate therapy.
6. The low cost of conformal external beam as compared to combinations of brachytherapy and external. 7. Quality assurance issues in brachytherapy in which the learning curve is long and physicians not trained in radiation oncology are frequently performing the technique. Brachytherapy shows promise but we should not lose sight of the many real concerns about its widespread implementation.