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154 Partial breast irradiation: Is it a validated treatment option?
$72 Tuesday, October 26, 2004
with PBB or whole breast RT (level III evidence). To date, only one phase III protocol has been initiated comparing the efficacy of PBB with whole breast RT. In this randomized trial, the 3year actuarial LR rate following PBB and whole breast RT was 1.3% and 1.9%, respectively (p = 0.99). The incidence of G2-3 late side-effects was 17% and 28%, respectively (p = 0.059). Significantly more patients were classified as having good/excellent cosmetic outcome in the PBB group (85% vs. 60%; p = 0.0001). In the light of contemporary clinical results eligibility criteria for APBI include: < 3 cm tumor diameter, unifocal non-lobular carcinoma without an EIC, clear surgical margins, and pN0-1a axillary status. Conclusions: PBB using proper patient selection, adequate implant technique and QA provides at least similar 5 to 7-year results to those achieved with standard whole breast RT. Having now obtained the results from phase I-II APBI studies supporting the concept of interstitial PBB, the next logical step is to obtain h i g h e r level evidence in carefully designed randomized studies. These multicentric phase Ill trials are under development by the NSABP and the GEC-ESTRO Breast Cancer Working Group. 154 Partial breast irradiation: Is it a validated treatment option?
H. Bartelink The Netherlands Cancer Institute, Department of Radiotherapy, Amsterdam, The Netherlands In the past century breast-conserving therapy has been carefully introduced into daily clinical practice after initial pilot experience followed by several randomized trials comparing mastectomy with breast-conserving therapy. In publications and at scientific meetings it was acknowledged that breastconserving therapy could safely be introduced into clinical practice without jeopardizing the breast cancer patient's future. Since then more detailed information became available from randomized trials on treatment details. For example, a dose effect relationship was found that showed that in young patients a higher radiation dose was required. This dose effect relationship was demonstrated in a trial with more than 5000 patients. Also, several studies have been carried out investigating the possibility of performing breast-conserving therapy without radiotherapy. Until so far all these studies have demonstrated that, even in selected cases with good prognosis, radiotherapy is able to reduce the local recurrence rate with a factor of 3 to 4. Long-term follow up showed even an improvement in survival by adding radiotherapy to tumorectomy. Recently in several institutes, partial breast irradiation has become a treatment option for breast cancer patients. However, this treatment option is proposed to patients without any validation in randomized trials. On the contrary, a randomized trial from the Milan group demonstrated the need for Whole breast irradiation~ quadrantectomy alone resulted in inferior results compared with tumorectomy plus whole breast irradiation. The treatment techniques used in partial breast irradiation are also questionable, for example the approach of putting a balloon with a radioactive source (or even worse a 50 KeV source) into the operation cavity. These clinicians wrongly expect that the operation cavity represent the original tumor with sufficient margin. From several pathology studies it is known for fact that the tumor is generally never exactly in the center of the operation specimen but is usually located eccentrically. A homogeneous irradiation of an operation cavity is therefore not directed to the areas where most of the tumor is left behind after surgery.
Symposia
Some clinical trials have been started, however, we will have to wait several years for the long-term follow-up data before concluding that it is safe to use partial breast irradiation in daily clinical practice. Real progress would be that these trials use the possibilities of microarrays and proteomics on frozen tumor material and blood, to allow future individual adaptation of the given treatment based upon their profile. Conclusion: Partial breast irradiation instead of whole breast irradiation is now being tested in a few randomized trials. Although this approach may be useful in certain patients it still cannot be accepted as standard treatment since no long-term follow-up data have been presented and no proper selection criteria exists. 155 Target determination and techniques of PBI
V. Strnad Strahlenth. Klinik und Poliklinik, Radiation Oncology, Erlangen, Germany The main advantage of the sole brachytherapy in the organ conserving treatment of breast cancer is the potential to improve the quality of life for patients. The target volume for the brachytherapy consists of the tumor bed with an adequate safety margin in all directions. Depending on whether clips are present or not, the tumor bed has to be defined with the help of a conventional simulator or an Integrated Brachytherapy Unit (IBU) or a CT-unit. For partial breast irradiation different treatment techniques can be used: 1. Multicatheter system, 2.Balloon technique 3. Single-fraction intraoperative radiation therapy 4.External beam intensity modulated radiotherapy. Each technique has advantages and disadvantages. With the multicatheter system the main advantages are that the tumour parameters are exactly known at the time of implantation, and that the target volume coverage is not limited in form and volume. Further advantages of the multicatheter system are, that it has very good reproducibility and the fact that the treatment planning is simple and reliable. Considered as possible disadvantage is an individually long learning curve. With the balloon system the advantages are a short learning curve, good reproducibility and only one puncture site. The main disadvantages of the balloon system are, that the target volume coverage is very limited in form and volume, and that the tumour parameters are not exactly known at the time of implantation. For the intraoperative radiation therapy 2 methods are available. Single fraction 21 Gy with an IORT dedicated accelerator allows good target volume coverage with sufficient dose. Disadvantage is that the tumour parameters are not exactly known at the time of irradiation and that the availability of this expensive system is limited. Single fraction 5 Gy with 50 kV x-ray machine has only disadvantages: beside typical disadvantages of IORT, the dose distribution is extremely limited in form and volume and allows only insufficient 5 Gy single fraction in 1 cm tissue depth. Partial-breast external beam intensity modulated radiotherapy has the same advantages as the multicatheter system. The problem is the daily breast fixation and high integral dose. Conclusion: 1.The PTV is defined the area around the resection cavity with a safety margin at least 10-20 mm. 2. To date the long term result are available only for the multicatheter system - excellent local control, minimal side effects, excellent cosmesis.
with PBB or whole breast RT (level III evidence). To date, only one phase III protocol has been initiated comparing the efficacy of PBB with whole breast RT. In this randomized trial, the 3year actuarial LR rate following PBB and whole breast RT was 1.3% and 1.9%, respectively (p = 0.99). The incidence of G2-3 late side-effects was 17% and 28%, respectively (p = 0.059). Significantly more patients were classified as having good/excellent cosmetic outcome in the PBB group (85% vs. 60%; p = 0.0001). In the light of contemporary clinical results eligibility criteria for APBI include: < 3 cm tumor diameter, unifocal non-lobular carcinoma without an EIC, clear surgical margins, and pN0-1a axillary status. Conclusions: PBB using proper patient selection, adequate implant technique and QA provides at least similar 5 to 7-year results to those achieved with standard whole breast RT. Having now obtained the results from phase I-II APBI studies supporting the concept of interstitial PBB, the next logical step is to obtain h i g h e r level evidence in carefully designed randomized studies. These multicentric phase Ill trials are under development by the NSABP and the GEC-ESTRO Breast Cancer Working Group. 154 Partial breast irradiation: Is it a validated treatment option?
H. Bartelink The Netherlands Cancer Institute, Department of Radiotherapy, Amsterdam, The Netherlands In the past century breast-conserving therapy has been carefully introduced into daily clinical practice after initial pilot experience followed by several randomized trials comparing mastectomy with breast-conserving therapy. In publications and at scientific meetings it was acknowledged that breastconserving therapy could safely be introduced into clinical practice without jeopardizing the breast cancer patient's future. Since then more detailed information became available from randomized trials on treatment details. For example, a dose effect relationship was found that showed that in young patients a higher radiation dose was required. This dose effect relationship was demonstrated in a trial with more than 5000 patients. Also, several studies have been carried out investigating the possibility of performing breast-conserving therapy without radiotherapy. Until so far all these studies have demonstrated that, even in selected cases with good prognosis, radiotherapy is able to reduce the local recurrence rate with a factor of 3 to 4. Long-term follow up showed even an improvement in survival by adding radiotherapy to tumorectomy. Recently in several institutes, partial breast irradiation has become a treatment option for breast cancer patients. However, this treatment option is proposed to patients without any validation in randomized trials. On the contrary, a randomized trial from the Milan group demonstrated the need for Whole breast irradiation~ quadrantectomy alone resulted in inferior results compared with tumorectomy plus whole breast irradiation. The treatment techniques used in partial breast irradiation are also questionable, for example the approach of putting a balloon with a radioactive source (or even worse a 50 KeV source) into the operation cavity. These clinicians wrongly expect that the operation cavity represent the original tumor with sufficient margin. From several pathology studies it is known for fact that the tumor is generally never exactly in the center of the operation specimen but is usually located eccentrically. A homogeneous irradiation of an operation cavity is therefore not directed to the areas where most of the tumor is left behind after surgery.
Symposia
Some clinical trials have been started, however, we will have to wait several years for the long-term follow-up data before concluding that it is safe to use partial breast irradiation in daily clinical practice. Real progress would be that these trials use the possibilities of microarrays and proteomics on frozen tumor material and blood, to allow future individual adaptation of the given treatment based upon their profile. Conclusion: Partial breast irradiation instead of whole breast irradiation is now being tested in a few randomized trials. Although this approach may be useful in certain patients it still cannot be accepted as standard treatment since no long-term follow-up data have been presented and no proper selection criteria exists. 155 Target determination and techniques of PBI
V. Strnad Strahlenth. Klinik und Poliklinik, Radiation Oncology, Erlangen, Germany The main advantage of the sole brachytherapy in the organ conserving treatment of breast cancer is the potential to improve the quality of life for patients. The target volume for the brachytherapy consists of the tumor bed with an adequate safety margin in all directions. Depending on whether clips are present or not, the tumor bed has to be defined with the help of a conventional simulator or an Integrated Brachytherapy Unit (IBU) or a CT-unit. For partial breast irradiation different treatment techniques can be used: 1. Multicatheter system, 2.Balloon technique 3. Single-fraction intraoperative radiation therapy 4.External beam intensity modulated radiotherapy. Each technique has advantages and disadvantages. With the multicatheter system the main advantages are that the tumour parameters are exactly known at the time of implantation, and that the target volume coverage is not limited in form and volume. Further advantages of the multicatheter system are, that it has very good reproducibility and the fact that the treatment planning is simple and reliable. Considered as possible disadvantage is an individually long learning curve. With the balloon system the advantages are a short learning curve, good reproducibility and only one puncture site. The main disadvantages of the balloon system are, that the target volume coverage is very limited in form and volume, and that the tumour parameters are not exactly known at the time of implantation. For the intraoperative radiation therapy 2 methods are available. Single fraction 21 Gy with an IORT dedicated accelerator allows good target volume coverage with sufficient dose. Disadvantage is that the tumour parameters are not exactly known at the time of irradiation and that the availability of this expensive system is limited. Single fraction 5 Gy with 50 kV x-ray machine has only disadvantages: beside typical disadvantages of IORT, the dose distribution is extremely limited in form and volume and allows only insufficient 5 Gy single fraction in 1 cm tissue depth. Partial-breast external beam intensity modulated radiotherapy has the same advantages as the multicatheter system. The problem is the daily breast fixation and high integral dose. Conclusion: 1.The PTV is defined the area around the resection cavity with a safety margin at least 10-20 mm. 2. To date the long term result are available only for the multicatheter system - excellent local control, minimal side effects, excellent cosmesis.