Should Ductal Carcinoma In Situ (DCIS) be Removed From the ASTRO Cautionary Group for Off-protocol Use of Accelerated Partial Breast Irradiation (APBI)? A Pooled Analysis of Outcomes for 300 Patients With DCIS treated With APBI

Abstract

Purpose/Objective(s)Limited data have been published regarding the validity of the ASTRO Consensus Panel (CP) guidelines and ductal carcinoma in situ (DCIS). The purpose of this study was to analyze patients with DCIS treated with APBI within a pooled set of patients treated on the American Society of Breast Surgeons (ASBrS) MammoSite Registry Trial.Materials/MethodsA total of 300 women with DCIS underwent APBI between April 1993 to November 2010 as part of the ASBrS Registry Trial (n = 192) or at WBH (n = 108). Patients with pure DCIS ≤3 cm (n = 125) were assigned to the cautionary risk group per ASTRO CP guidelines and analyzed compared to the pooled invasive suitable (n = 653) group and pooled invasive suitable/cautionary (n = 1,298) group with regards to ipsilateral breast tumor recurrence (IBTR), regional recurrence (RR), distant metastases (DM), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS).ResultsMedian age was 62 years (range: 50-83 years) and median tumor size was 6.0mm (range: 0.0-28.0 mm). DCIS patients were younger, with higher grade but smaller tumors, and were more likely to have close margins compared with the pooled suitable and suitable/cautionary groups. The rate of IBTR for all DCIS patients was 1.6% at five years with no RR or DM noted while CSS was 100% and OS was 95.8%. No differences in IBTR (1.6% vs. 2.4%, p = 0.68), RR (0% vs. 0.4%, p = 0.47), DM (0% vs. 0.8%, p = 0.32), DFS (100% vs. 96.3%, p = 0.14), or CSS (100% vs. 98.6%, p = 0.22) were noted between DCIS patients and pooled invasive suitable patients. OS, however, was improved in DCIS patients (95.8% vs. 90.9%, p = 0.03). Similar findings were seen for DCIS versus invasive suitable/cautionary patients including no differences in IBTR (1.6% vs. 3.1%, p = 0.46), RR (0% vs. 0.6%, p = 0.40), DM (0% vs. 2.5%, p = 0.11), or CSS (100% vs. 98.3%, p = 0.16) but improved DFS (100% vs. 94.4%, p = 0.04) and OS (95.8% vs. 90.8%, p = 0.03) were seen in DCIS patients. Findings were similar for DCIS patients 60 years and older (n = 74), except that OS was not significantly different.ConclusionsExcellent clinical outcomes were seen for both patients with invasive breast cancer within the suitable group as well as those with DCIS within the cautionary subgroup (98.4% local control at 5-years) despite more aggressive clinical-pathologic features in the DCIS cohort. This analysis of the largest published data of patients with DCIS treated with APBI supports consideration for removal of DCIS from the cautionary risk group as outcomes are similar (and excellent) in a large pooled analysis. Purpose/Objective(s)Limited data have been published regarding the validity of the ASTRO Consensus Panel (CP) guidelines and ductal carcinoma in situ (DCIS). The purpose of this study was to analyze patients with DCIS treated with APBI within a pooled set of patients treated on the American Society of Breast Surgeons (ASBrS) MammoSite Registry Trial. Limited data have been published regarding the validity of the ASTRO Consensus Panel (CP) guidelines and ductal carcinoma in situ (DCIS). The purpose of this study was to analyze patients with DCIS treated with APBI within a pooled set of patients treated on the American Society of Breast Surgeons (ASBrS) MammoSite Registry Trial. Materials/MethodsA total of 300 women with DCIS underwent APBI between April 1993 to November 2010 as part of the ASBrS Registry Trial (n = 192) or at WBH (n = 108). Patients with pure DCIS ≤3 cm (n = 125) were assigned to the cautionary risk group per ASTRO CP guidelines and analyzed compared to the pooled invasive suitable (n = 653) group and pooled invasive suitable/cautionary (n = 1,298) group with regards to ipsilateral breast tumor recurrence (IBTR), regional recurrence (RR), distant metastases (DM), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS). A total of 300 women with DCIS underwent APBI between April 1993 to November 2010 as part of the ASBrS Registry Trial (n = 192) or at WBH (n = 108). Patients with pure DCIS ≤3 cm (n = 125) were assigned to the cautionary risk group per ASTRO CP guidelines and analyzed compared to the pooled invasive suitable (n = 653) group and pooled invasive suitable/cautionary (n = 1,298) group with regards to ipsilateral breast tumor recurrence (IBTR), regional recurrence (RR), distant metastases (DM), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS). ResultsMedian age was 62 years (range: 50-83 years) and median tumor size was 6.0mm (range: 0.0-28.0 mm). DCIS patients were younger, with higher grade but smaller tumors, and were more likely to have close margins compared with the pooled suitable and suitable/cautionary groups. The rate of IBTR for all DCIS patients was 1.6% at five years with no RR or DM noted while CSS was 100% and OS was 95.8%. No differences in IBTR (1.6% vs. 2.4%, p = 0.68), RR (0% vs. 0.4%, p = 0.47), DM (0% vs. 0.8%, p = 0.32), DFS (100% vs. 96.3%, p = 0.14), or CSS (100% vs. 98.6%, p = 0.22) were noted between DCIS patients and pooled invasive suitable patients. OS, however, was improved in DCIS patients (95.8% vs. 90.9%, p = 0.03). Similar findings were seen for DCIS versus invasive suitable/cautionary patients including no differences in IBTR (1.6% vs. 3.1%, p = 0.46), RR (0% vs. 0.6%, p = 0.40), DM (0% vs. 2.5%, p = 0.11), or CSS (100% vs. 98.3%, p = 0.16) but improved DFS (100% vs. 94.4%, p = 0.04) and OS (95.8% vs. 90.8%, p = 0.03) were seen in DCIS patients. Findings were similar for DCIS patients 60 years and older (n = 74), except that OS was not significantly different. Median age was 62 years (range: 50-83 years) and median tumor size was 6.0mm (range: 0.0-28.0 mm). DCIS patients were younger, with higher grade but smaller tumors, and were more likely to have close margins compared with the pooled suitable and suitable/cautionary groups. The rate of IBTR for all DCIS patients was 1.6% at five years with no RR or DM noted while CSS was 100% and OS was 95.8%. No differences in IBTR (1.6% vs. 2.4%, p = 0.68), RR (0% vs. 0.4%, p = 0.47), DM (0% vs. 0.8%, p = 0.32), DFS (100% vs. 96.3%, p = 0.14), or CSS (100% vs. 98.6%, p = 0.22) were noted between DCIS patients and pooled invasive suitable patients. OS, however, was improved in DCIS patients (95.8% vs. 90.9%, p = 0.03). Similar findings were seen for DCIS versus invasive suitable/cautionary patients including no differences in IBTR (1.6% vs. 3.1%, p = 0.46), RR (0% vs. 0.6%, p = 0.40), DM (0% vs. 2.5%, p = 0.11), or CSS (100% vs. 98.3%, p = 0.16) but improved DFS (100% vs. 94.4%, p = 0.04) and OS (95.8% vs. 90.8%, p = 0.03) were seen in DCIS patients. Findings were similar for DCIS patients 60 years and older (n = 74), except that OS was not significantly different. ConclusionsExcellent clinical outcomes were seen for both patients with invasive breast cancer within the suitable group as well as those with DCIS within the cautionary subgroup (98.4% local control at 5-years) despite more aggressive clinical-pathologic features in the DCIS cohort. This analysis of the largest published data of patients with DCIS treated with APBI supports consideration for removal of DCIS from the cautionary risk group as outcomes are similar (and excellent) in a large pooled analysis. Excellent clinical outcomes were seen for both patients with invasive breast cancer within the suitable group as well as those with DCIS within the cautionary subgroup (98.4% local control at 5-years) despite more aggressive clinical-pathologic features in the DCIS cohort. This analysis of the largest published data of patients with DCIS treated with APBI supports consideration for removal of DCIS from the cautionary risk group as outcomes are similar (and excellent) in a large pooled analysis.