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OC-133 PERIOPERATIVE HIGH DOSE RATE INTERSTITIAL BRACHYTHERAPY BOOST FOR PATIENTS WITH EARLY BREAST CANCER
S54
Conclusions: The current restrictions utilized by the NSABP B39 offer Dmax skin dose constraints that sufficiently prevent hazardous outcomes. These findings further refine those constraints. Our experience suggest by limiting the skin Dmax to <100%, and V90 to less than 5cc's of the skin dermis, long-term good/excellent cosmesis can be anticipated. OC-133 PERIOPERATIVE HIGH DOSE RATE INTERSTITIAL BRACHYTHERAPY BOOST FOR PATIENTS WITH EARLY BREAST CANCER D.N. Sharma1, S.V.S. Deo2, G.K. Rath1, N.K. Shukla2, R. Madan1, S. Sharma1, P.K. Julka1 1 All India Institute of Medical Sciences, Radiation Oncology, New Delhi, India 2 All India Institute of Medical Sciences, Surgical Oncology, New Delhi, India Purpose/Objective: Conventionally, the boost therapy is given after the completion of whole breast radiation therapy (WBRT) in breast Mean dose (cGy)/fx Volume in cc
PTVeval
cavity rind
PTVeval cavity center peripheral center peripheral SAVI® 6+1mini
48
9
558
611
969
1191
®
SAVI 6+1
65
16
536
585
859
1058
®
SAVI 8+1
86
32
500
559
728
959
Contura®
100
48
470
N/A
650
N/A
Mammosite® 101
49
480
N/A
680
N/A
Interstitial NA NA 425 N/A 483 N/A conservation therapy for early breast cancer (EBC) patients. However, it can be delivered preceding WBRT during perioperative period by interstitial brachytherapy. We conducted a study to evaluate the role of perioperative high-dose-rate interstitial brachytherapy (PHDRIBT) boost treatment in the management of EBC. Materials and Methods: From year 2005-2010, 100 patients with EBC were enrolled into this study as per the eligibility criteria. The brachytherapy implant was performed in the surgical theater during the breast conservation surgery (BCS) procedure. The boost treatment was started on 3rd postoperative day to deliver a dose of 15 Gy in 6 fractions over 3 days. After an interval of 3 weeks, EBRT to whole breast was started for a prescription dose of 50 Gy by conventional fractionation. The end points of this study were local recurrence (LR), acute toxicity and cosmetic outcome. Results: Median age of the patients was 46 years and median follow up was 32 months (range 2-78 months). Majority of the patients (65) underwent two-plane implant and a median of 9 catheters (range 517) were implanted. The volumes receiving 100% (V100) and 150% (V150) of the prescribed dose were 118 cc and 52 cc respectively. Dose homogenity index (DHI) ranged from 0.64-0.92 with a median of 0.88. No patient developed LR but 5 patients developed distant metastases. The 5-year overall and disease free survival rates were 86% and 77% respectively. Eleven parents had acute toxicity; 4 wound complications and 7 grade III skin toxicity. Nine of these 11 patients had breast size of more than 1500 cc. Except the breast volume (>1500 cc), there was no statistically significant correlation between any of the patient or dosimetry related factors and the acute toxicity. Good-excellent cosmesis was observed in 87% of patients. Conclusions: Based on the results of our first dedicated series in the literature so far, PHDRIBT boost followed by WBRT provides excellent local control rate (100%), acceptable acute toxicity rate (11%) and good-excellent breast cosmesis rate (87%) in patients with EBC. OC-134 COMPARISON OF DOSE GRADIENT WITHIN THE PTVEVAL AS A FUNCTION OF OPTIMIZATION METHOD AND APPLICATOR USED IN APBI I.R. Marshall1, S. Rahnema2, E.G. Aguero1, N.C. Brackett3 1 Medical University of South Carolina, Radiation Oncology, Georgetown, USA
World Congress of Brachytherapy 2012 2
Georgetown Mem. Hospital SC, Radiation Oncology, Georgetown, USA 3 Coastal Carolina Breast Center, Surgery, Murrells Inlet SC, USA Purpose/Objective: The increased use of multi-channel catheters in accelerated partial breast irradiation (APBI) has resulted in different optimization techniques. In the case of the SAVI® applicator, where the peripheral catheters define the cavity, the difference in optimization makes a significant difference in the dose distribution within the PTVeval, especially in the first 2 mm of breast tissue named cavity rind. This study compares optimization based on heavily weighting the dwell times of the central catheter versus the peripheral catheters. Since the prescription dose is defined at 1cm from the cavity, the dose gradient within the PTVeval and cavity rind will vary as a function of optimization method used and applicator size. The results are compared with balloon type and interstitial applicators. Materials and Methods: At the time of this report the Georgetown Radiation Therapy Center (GRTC) has treated over 115 patients with the SAVI® catheter, 121 patients with the single lumen Mammosite® and 22 patients with the multi-channel Contura®. All APBI treatments were prescribed to the same PTVeval surface dose (340cGy/fx). We analyzed DVH distributions to provide D90, V150 and V200 of the PTVeval as well as cavity rind volumes which received 1000, 1500 and 2000cGy per fraction. The mean dose of the PTVeval and cavity rind for the SAVI® was compared to the Contura®, Mammosite® and simulated interstitial applicators. Results: Significant differences were not seen in the PTVeval V150 and V200 as a function of optimization method. However, the percentage of tissue volume receiving 1000, 1500 and 2000cGy per fraction in the cavity rind was on average about 3 times larger for peripheral optimization versus central optimization. The mean dose to the PTVeval and cavity rind as a function of optimization method, applicator type and size was evaluated and is presented in the table.
Conclusions: Since the peripheral catheters of a SAVI® applicator are in direct contact with breast tissue, a prescription dose defined to 1 cm results in a significant dose gradient within the PTVeval. Based on our results, we conclude that maximizing the dwell times in the central catheter while using the peripheral catheters for molding of the dose distribution significantly reduces the dose gradient by taking advantage of the inverse square law. Further investigation is required to determine whether a higher mean dose to the PTVeval and cavity rind as with the SAVI® applicator versus balloon and interstitial applicators will result in higher treatment toxicity or better outcomes. OC-135 DOES ONCOPLASTIC BREAST CONSERVING SURGERY CONTRAINDICATE PARTIAL BREAST MULTICATHETER BRACHYTHERAPY (APBI)? A. Roth1, D. Kauer-Dorner2, A. Resch2, P. Niehoff3, C. Melchert1, D. Berger2, G. Kovács1 1 University of Luebeck, Interdisciplinary Brachytherapy, Luebeck, Germany 2 AKH-Vienna, Radiotherapy, Vienna, Austria 3 Kliniken der Stadt Köln, Radiotherapy, Cologne, Germany Purpose/Objective: Treatment results of adjuvant PDR- and HDR multicatheter partial breast implants were retrospectively analyzed in
Conclusions: The current restrictions utilized by the NSABP B39 offer Dmax skin dose constraints that sufficiently prevent hazardous outcomes. These findings further refine those constraints. Our experience suggest by limiting the skin Dmax to <100%, and V90 to less than 5cc's of the skin dermis, long-term good/excellent cosmesis can be anticipated. OC-133 PERIOPERATIVE HIGH DOSE RATE INTERSTITIAL BRACHYTHERAPY BOOST FOR PATIENTS WITH EARLY BREAST CANCER D.N. Sharma1, S.V.S. Deo2, G.K. Rath1, N.K. Shukla2, R. Madan1, S. Sharma1, P.K. Julka1 1 All India Institute of Medical Sciences, Radiation Oncology, New Delhi, India 2 All India Institute of Medical Sciences, Surgical Oncology, New Delhi, India Purpose/Objective: Conventionally, the boost therapy is given after the completion of whole breast radiation therapy (WBRT) in breast Mean dose (cGy)/fx Volume in cc
PTVeval
cavity rind
PTVeval cavity center peripheral center peripheral SAVI® 6+1mini
48
9
558
611
969
1191
®
SAVI 6+1
65
16
536
585
859
1058
®
SAVI 8+1
86
32
500
559
728
959
Contura®
100
48
470
N/A
650
N/A
Mammosite® 101
49
480
N/A
680
N/A
Interstitial NA NA 425 N/A 483 N/A conservation therapy for early breast cancer (EBC) patients. However, it can be delivered preceding WBRT during perioperative period by interstitial brachytherapy. We conducted a study to evaluate the role of perioperative high-dose-rate interstitial brachytherapy (PHDRIBT) boost treatment in the management of EBC. Materials and Methods: From year 2005-2010, 100 patients with EBC were enrolled into this study as per the eligibility criteria. The brachytherapy implant was performed in the surgical theater during the breast conservation surgery (BCS) procedure. The boost treatment was started on 3rd postoperative day to deliver a dose of 15 Gy in 6 fractions over 3 days. After an interval of 3 weeks, EBRT to whole breast was started for a prescription dose of 50 Gy by conventional fractionation. The end points of this study were local recurrence (LR), acute toxicity and cosmetic outcome. Results: Median age of the patients was 46 years and median follow up was 32 months (range 2-78 months). Majority of the patients (65) underwent two-plane implant and a median of 9 catheters (range 517) were implanted. The volumes receiving 100% (V100) and 150% (V150) of the prescribed dose were 118 cc and 52 cc respectively. Dose homogenity index (DHI) ranged from 0.64-0.92 with a median of 0.88. No patient developed LR but 5 patients developed distant metastases. The 5-year overall and disease free survival rates were 86% and 77% respectively. Eleven parents had acute toxicity; 4 wound complications and 7 grade III skin toxicity. Nine of these 11 patients had breast size of more than 1500 cc. Except the breast volume (>1500 cc), there was no statistically significant correlation between any of the patient or dosimetry related factors and the acute toxicity. Good-excellent cosmesis was observed in 87% of patients. Conclusions: Based on the results of our first dedicated series in the literature so far, PHDRIBT boost followed by WBRT provides excellent local control rate (100%), acceptable acute toxicity rate (11%) and good-excellent breast cosmesis rate (87%) in patients with EBC. OC-134 COMPARISON OF DOSE GRADIENT WITHIN THE PTVEVAL AS A FUNCTION OF OPTIMIZATION METHOD AND APPLICATOR USED IN APBI I.R. Marshall1, S. Rahnema2, E.G. Aguero1, N.C. Brackett3 1 Medical University of South Carolina, Radiation Oncology, Georgetown, USA
World Congress of Brachytherapy 2012 2
Georgetown Mem. Hospital SC, Radiation Oncology, Georgetown, USA 3 Coastal Carolina Breast Center, Surgery, Murrells Inlet SC, USA Purpose/Objective: The increased use of multi-channel catheters in accelerated partial breast irradiation (APBI) has resulted in different optimization techniques. In the case of the SAVI® applicator, where the peripheral catheters define the cavity, the difference in optimization makes a significant difference in the dose distribution within the PTVeval, especially in the first 2 mm of breast tissue named cavity rind. This study compares optimization based on heavily weighting the dwell times of the central catheter versus the peripheral catheters. Since the prescription dose is defined at 1cm from the cavity, the dose gradient within the PTVeval and cavity rind will vary as a function of optimization method used and applicator size. The results are compared with balloon type and interstitial applicators. Materials and Methods: At the time of this report the Georgetown Radiation Therapy Center (GRTC) has treated over 115 patients with the SAVI® catheter, 121 patients with the single lumen Mammosite® and 22 patients with the multi-channel Contura®. All APBI treatments were prescribed to the same PTVeval surface dose (340cGy/fx). We analyzed DVH distributions to provide D90, V150 and V200 of the PTVeval as well as cavity rind volumes which received 1000, 1500 and 2000cGy per fraction. The mean dose of the PTVeval and cavity rind for the SAVI® was compared to the Contura®, Mammosite® and simulated interstitial applicators. Results: Significant differences were not seen in the PTVeval V150 and V200 as a function of optimization method. However, the percentage of tissue volume receiving 1000, 1500 and 2000cGy per fraction in the cavity rind was on average about 3 times larger for peripheral optimization versus central optimization. The mean dose to the PTVeval and cavity rind as a function of optimization method, applicator type and size was evaluated and is presented in the table.
Conclusions: Since the peripheral catheters of a SAVI® applicator are in direct contact with breast tissue, a prescription dose defined to 1 cm results in a significant dose gradient within the PTVeval. Based on our results, we conclude that maximizing the dwell times in the central catheter while using the peripheral catheters for molding of the dose distribution significantly reduces the dose gradient by taking advantage of the inverse square law. Further investigation is required to determine whether a higher mean dose to the PTVeval and cavity rind as with the SAVI® applicator versus balloon and interstitial applicators will result in higher treatment toxicity or better outcomes. OC-135 DOES ONCOPLASTIC BREAST CONSERVING SURGERY CONTRAINDICATE PARTIAL BREAST MULTICATHETER BRACHYTHERAPY (APBI)? A. Roth1, D. Kauer-Dorner2, A. Resch2, P. Niehoff3, C. Melchert1, D. Berger2, G. Kovács1 1 University of Luebeck, Interdisciplinary Brachytherapy, Luebeck, Germany 2 AKH-Vienna, Radiotherapy, Vienna, Austria 3 Kliniken der Stadt Köln, Radiotherapy, Cologne, Germany Purpose/Objective: Treatment results of adjuvant PDR- and HDR multicatheter partial breast implants were retrospectively analyzed in