Long-Term Clinical and Cosmetic Outcomes of Accelerated Partial Breast Irradiation (APBI) with Multi-Lumen Applicators in Patients with Skin Spacing ≤ 7 mm

PurposeIn the Mammosite registry trial, skin spacing of > 7 mm was associated with better cosmetic outcome. The advent of multi-lumen applicators allowed for more conformal dosimetry and minimization of dose to the skin even with close spacing. In the reported initial SAVI experience, some patients had ≤7 mm skin spacing although the specific outcomes relating to those patients were not reported separately. The acute toxicity and early cosmetic results of patients with ≤ 7 mm treated with multi-lumen catheters have been reported previously but long-term results in this population are limited. We undertook this study to retrospectively examine the acute and long-term toxicity along with clinical and cosmetic outcome of patients with close skin spacing treated at our institution.Materials and MethodsAfter being granted approval from our institutional review board, we retrospectively reviewed all patients who had undergone accelerated partial breast irradiation (APBI) in a single institution with multi-lumen devices from 2008 to 2012. All patients were treated to 3400 cGy prescribed to PTV_EVAL in twice-daily fractionation over five days using either Contura or SAVI device. Based on our institutional protocols in place at the time of treatment, all efforts were made to keep the maximum skin dose to < 145% of prescribed dose for Contura devices and <110% for SAVI devices during treatment planning.ResultsWe identified 37 patients and 38 lesions with spacing of ≤7 mm between the applicator and skin with long-term follow-up (one patient had bilateral treatment). The patient characteristics are listed in table 1. Four lesions were treated with SAVI device and 34 with Contura. Median distance from device to skin was 4.85 mm (1.6-7.0 mm) and the median maximum skin dose was 117.6% of prescribed dose (81.8-127.7%). Median breast tissue V150 and V200 were 27 and 9.3 cc and median PTV_EVAL V95 and V100 were 96.3% (88.5-99.6%) and 91.8%(84.3-98.4). Based on RTOG radiation morbidity criteria, 22 treated patients experienced grade 1 and 9 patients experienced grade 2 acute toxicity. Twenty-one patients experienced late grade 1 toxicity and there were no grade 2 late toxicities. Based on the Harvard cosmesis grading scale, 24 treated sites had excellent and 11 had good cosmetic outcome with no cosmetic outcome recorded for 3 patients. There was one ipsilateral breast recurrence, one ipsilateral axillary recurrence, and one recorded case of mastectomy due to mastitis. Overall cosmetic outcome trended towards a significant correlation with skin spacing. Additionally, all patients with ≤ 3 mm skin spacing experienced grade 1 or 2 acute and long-term toxicities. All 5 treated breasts with ≤ 3 mm skin spacing had good cosmetic outcome but none had an excellent outcome.ConclusionsTabled 1Patient characteristicsTotal number or Median (range)Total number of treated lesions38 Left-sided19 Right-sided19Median age at time of diagnosis63 (44-86)Additional theraphy Neoadjuvant hormonal2 Adjuvant hormonal26 Adjuvant chemotheraphy2Lesion size8.5 mm (6-24)Node negative38Pathology DCIS11 DCIS + Invasive carcinoma5 Invasive carcinoma22Margin Status Negative37 Focally Positive1Hormone Receptor Status Positive33 Negative5 Open table in a new tab PurposeIn the Mammosite registry trial, skin spacing of > 7 mm was associated with better cosmetic outcome. The advent of multi-lumen applicators allowed for more conformal dosimetry and minimization of dose to the skin even with close spacing. In the reported initial SAVI experience, some patients had ≤7 mm skin spacing although the specific outcomes relating to those patients were not reported separately. The acute toxicity and early cosmetic results of patients with ≤ 7 mm treated with multi-lumen catheters have been reported previously but long-term results in this population are limited. We undertook this study to retrospectively examine the acute and long-term toxicity along with clinical and cosmetic outcome of patients with close skin spacing treated at our institution. In the Mammosite registry trial, skin spacing of > 7 mm was associated with better cosmetic outcome. The advent of multi-lumen applicators allowed for more conformal dosimetry and minimization of dose to the skin even with close spacing. In the reported initial SAVI experience, some patients had ≤7 mm skin spacing although the specific outcomes relating to those patients were not reported separately. The acute toxicity and early cosmetic results of patients with ≤ 7 mm treated with multi-lumen catheters have been reported previously but long-term results in this population are limited. We undertook this study to retrospectively examine the acute and long-term toxicity along with clinical and cosmetic outcome of patients with close skin spacing treated at our institution. Materials and MethodsAfter being granted approval from our institutional review board, we retrospectively reviewed all patients who had undergone accelerated partial breast irradiation (APBI) in a single institution with multi-lumen devices from 2008 to 2012. All patients were treated to 3400 cGy prescribed to PTV_EVAL in twice-daily fractionation over five days using either Contura or SAVI device. Based on our institutional protocols in place at the time of treatment, all efforts were made to keep the maximum skin dose to < 145% of prescribed dose for Contura devices and <110% for SAVI devices during treatment planning. After being granted approval from our institutional review board, we retrospectively reviewed all patients who had undergone accelerated partial breast irradiation (APBI) in a single institution with multi-lumen devices from 2008 to 2012. All patients were treated to 3400 cGy prescribed to PTV_EVAL in twice-daily fractionation over five days using either Contura or SAVI device. Based on our institutional protocols in place at the time of treatment, all efforts were made to keep the maximum skin dose to < 145% of prescribed dose for Contura devices and <110% for SAVI devices during treatment planning. ResultsWe identified 37 patients and 38 lesions with spacing of ≤7 mm between the applicator and skin with long-term follow-up (one patient had bilateral treatment). The patient characteristics are listed in table 1. Four lesions were treated with SAVI device and 34 with Contura. Median distance from device to skin was 4.85 mm (1.6-7.0 mm) and the median maximum skin dose was 117.6% of prescribed dose (81.8-127.7%). Median breast tissue V150 and V200 were 27 and 9.3 cc and median PTV_EVAL V95 and V100 were 96.3% (88.5-99.6%) and 91.8%(84.3-98.4). Based on RTOG radiation morbidity criteria, 22 treated patients experienced grade 1 and 9 patients experienced grade 2 acute toxicity. Twenty-one patients experienced late grade 1 toxicity and there were no grade 2 late toxicities. Based on the Harvard cosmesis grading scale, 24 treated sites had excellent and 11 had good cosmetic outcome with no cosmetic outcome recorded for 3 patients. There was one ipsilateral breast recurrence, one ipsilateral axillary recurrence, and one recorded case of mastectomy due to mastitis. Overall cosmetic outcome trended towards a significant correlation with skin spacing. Additionally, all patients with ≤ 3 mm skin spacing experienced grade 1 or 2 acute and long-term toxicities. All 5 treated breasts with ≤ 3 mm skin spacing had good cosmetic outcome but none had an excellent outcome. We identified 37 patients and 38 lesions with spacing of ≤7 mm between the applicator and skin with long-term follow-up (one patient had bilateral treatment). The patient characteristics are listed in table 1. Four lesions were treated with SAVI device and 34 with Contura. Median distance from device to skin was 4.85 mm (1.6-7.0 mm) and the median maximum skin dose was 117.6% of prescribed dose (81.8-127.7%). Median breast tissue V150 and V200 were 27 and 9.3 cc and median PTV_EVAL V95 and V100 were 96.3% (88.5-99.6%) and 91.8%(84.3-98.4). Based on RTOG radiation morbidity criteria, 22 treated patients experienced grade 1 and 9 patients experienced grade 2 acute toxicity. Twenty-one patients experienced late grade 1 toxicity and there were no grade 2 late toxicities. Based on the Harvard cosmesis grading scale, 24 treated sites had excellent and 11 had good cosmetic outcome with no cosmetic outcome recorded for 3 patients. There was one ipsilateral breast recurrence, one ipsilateral axillary recurrence, and one recorded case of mastectomy due to mastitis. Overall cosmetic outcome trended towards a significant correlation with skin spacing. Additionally, all patients with ≤ 3 mm skin spacing experienced grade 1 or 2 acute and long-term toxicities. All 5 treated breasts with ≤ 3 mm skin spacing had good cosmetic outcome but none had an excellent outcome. ConclusionsTabled 1Patient characteristicsTotal number or Median (range)Total number of treated lesions38 Left-sided19 Right-sided19Median age at time of diagnosis63 (44-86)Additional theraphy Neoadjuvant hormonal2 Adjuvant hormonal26 Adjuvant chemotheraphy2Lesion size8.5 mm (6-24)Node negative38Pathology DCIS11 DCIS + Invasive carcinoma5 Invasive carcinoma22Margin Status Negative37 Focally Positive1Hormone Receptor Status Positive33 Negative5 Open table in a new tab