Breast Surgeons MammoSite Registry Trial Research Articles

Nomogram for Predicting the Risk of Locoregional Recurrence in Patients Treated With Accelerated Partial-Breast Irradiation

To develop a nomogram taking into account clinicopathologic features to predict locoregional recurrence (LRR) in patients treated with accelerated partial-breast irradiation (APBI) for early-stage breast cancer. A total of 2000 breasts (1990 women) were treated with APBI at William Beaumont Hospital (n=551) or on the American Society of Breast Surgeons MammoSite Registry Trial (n=1449). Techniques included multiplanar interstitial catheters (n=98), balloon-based brachytherapy (n=1689), and 3-dimensional conformal radiation therapy (n=213). Clinicopathologic variables were gathered prospectively. A nomogram was formulated utilizing the Cox proportional hazards regression model to predict for LRR. This was validated by generating a bias-corrected index and cross-validated with a concordance index. Median follow-up was 5.5 years (range, 0.9-18.3 years). Of the 2000 cases, 435 were excluded because of missing data. Univariate analysis found that age <50 years, pre-/perimenopausal status, close/positive margins, estrogen receptor negativity, and high grade were associated with a higher frequency of LRR. These 5 independent covariates were used to create adjusted estimates, weighting each on a scale of 0-100. The total score is identified on a points scale to obtain the probability of an LRR over the study period. The model demonstrated good concordance for predicting LRR, with a concordance index of 0.641. The formulation of a practical, easy-to-use nomogram for calculating the risk of LRR in patients undergoing APBI will help guide the appropriate selection of patients for off-protocol utilization of APBI.

Should Ductal Carcinoma-in-situ (DCIS) Be Removed from the ASTRO Consensus Panel 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

To analyze outcomes in patients with ductal carcinoma-in-situ (DCIS) treated with accelerated partial breast irradiation (APBI) within a pooled set of patients. A total of 300 women with DCIS underwent APBI between April 1993 and November 2010 as part of American Society of Breast Surgeons MammoSite Registry Trial (n=192) or at William Beaumont Hospital (n=108). Patients with pure DCIS <3cm (n=125) were assigned to the cautionary risk group per American Society of Radiation Oncology consensus panel guidelines for off-protocol use of APBI and analyzed compared to a pooled invasive suitable (n=653) risk group and pooled invasive suitable/cautionary (n=1,298) risk group. The rate of ipsilateral breast tumor recurrence (IBTR) for all 300 DCIS patients was 2.6% at 5years with no regional recurrences, while cause-specific survival was 99.5% and overall survival (OS) was 96.4%. When comparing the cautionary DCIS group to the invasive suitable/cautionary group, no difference in IBTR was noted (2.6 vs. 3.1%, P=0.90) with significant improvements in distant metastases (0 vs. 2.5 %, P=0.05), disease-free survival (98.5 vs. 94.4 %, P=0.05), and OS (95.7 vs. 90.8 %, P=0.03) noted for DCIS patients. When comparing cautionary DCIS patients to invasive suitable patients, no difference in IBTR were noted (2.6 vs. 2.4 %, P=0.76), while improved OS for DCIS patients was noted (95.7 vs. 90.9 %, P=0.02). This analysis of the largest cohort of patients with DCIS treated with APBI supports previously reported excellent outcomes; as a result of small numbers of events, further data are necessary to confirm these findings.

Evaluation of current consensus panel guidelines for APBI: A pooled analysis of William Beaumont Hospital and American Society of Breast Surgeons MammoSite registry trial data.

145 Background: To determine whether the ASTRO Consensus Panel (CP) guidelines for accelerated partial breast irradiation (APBI) are associated with significantly different outcomes in a pooled analysis from William Beaumont Hospital (WBH) and the American Society of Breast Surgeons (ASBrS) MammoSite Registry Trial. Methods: 2,127 cases of early-stage breast cancer were treated using APBI (WBH: n=678; ASBrS: n=1,449). Three forms of APBI were used at WBH (interstitial, n=221; balloon-based, n=255; or 3D-CRT, n=206) while all Registry Trial patients received balloon-based brachytherapy. Patients with complete coding necessary for ASTRO CP assignment (n=1,813) were divided into suitable (n=661, 36.5%), cautionary (n=850, 46.9%), and unsuitable (n=302, 16.7%) categories. Tumor characteristics and clinical outcomes were analyzed according to CP group. Results: Median age was 65 years (32-94 years) and median tumor size was 10.0mm (0-45mm). The WBH cohort had more node-positive disease (6.9% vs. 2.6%, p&lt;0.01) and cautionary patients (49.5% vs. 41.8%, p=0.06). Five-year rates of ipsilateral breast tumor recurrence (IBTR), regional nodal failure (RNF), and distant metastasis (DM) for the whole cohort were 2.8%, 0.6%, 1.6%, respectively. When analyzed by CP group, the rate of IBTR was not statistically higher for suitable (2.5%), cautionary (3.3%), or unsuitable (4.6%) patients (p=0.20). The non-significant increase in IBTR for grouped cautionary/unsuitable categories was due to increased elsewhere failures/new primaries (p=0.04), not true recurrences (1.1-1.2%, all groups, p=0.94). A higher rate of DM was observed within the cautionary and unsuitable groups (3.3-3.6% vs. 0.7% for suitable, p=0.01), although cause-specific survival was the same for all patient categories (98.0-98.6%, all groups, p=0.47). Conclusions: Excellent outcomes following breast conserving surgery and APBI were seen in our pooled analysis. The current ASTRO CP guidelines did not adequately differentiate patients at an increased risk of IBTR or tumor bed failure within the largest patient population of cases treated with APBI to date.

Axillary Failure in Patients Treated with MammoSite Accelerated Partial Breast Irradiation

The risk of axillary failure (AF) after accelerated partial breast irradiation (APBI) using MammoSite brachytherapy is unknown and has been source of concern as the axillary region is not treated with this technique. We aimed to determine the rate of AF in patients treated with APBI and identify factors associated with its occurrence. Data from the American Society of Breast Surgeons MammoSite Registry Trial were reviewed and patients with AF were identified. Clinical, pathologic and treatment-related variables were analyzed to determine which factors were associated with AF. A total of 1440 patients underwent MammoSite APBI. A total of 1449 cases were treated (9 patients received bilateral treatment), 1255 cases (87%) of invasive breast cancer and 194 cases (13%) of ductal carcinoma in situ (DCIS). The median length of follow-up was 59 months. There were 10 patients who had an AF. Of these, 9 patients had an initial diagnosis of invasive cancer and 1 had an initial diagnosis of DCIS. The 5-year actuarial rate of AF was 0.79%. The only independent risk factor for AF identified by multivariate analysis was the presence of high-grade disease (P=.008). The 5-year overall survival rate in patients with an AF was 77.8% (there was 1 death related to breast cancer). The rate of AF after MammoSite APBI is low and appears to be similar to that achieved with whole-breast irradiation.

Five‐year outcome of patients classified using the American Society for Radiation Oncology consensus statement guidelines for the application of accelerated partial breast irradiation

The American Society for Radiation Oncology (ASTRO) consensus statement (CS) for the application of accelerated partial breast irradiation (APBI) was applied to patients who were treated with this technique on the American Society of Breast Surgeons MammoSite Registry Trial to determine potential differences in clinical outcome based on classification group. Patients were classified based on the CS groups of "suitable," "cautionary," and "unsuitable." Rates of ipsilateral breast tumor recurrence (IBTR), regional lymph node failure, distant metastases, disease-free survival, cause-specific survival, and overall survival were assessed. Of the 1449 cases who were treated, 1025 patients (71%) could be classified according to the CS groupings, including 419 patients (41%) who fit the "suitable" criteria, 430 patients (42%) who fit the "cautionary" criteria, and 176 patients (17%) who fit the "unsuitable" criteria. At a median follow-up of 53.5 months, the 5-year actuarial rates of IBTR for the "suitable," "cautionary," and "unsuitable" groups were 2.59%, 5.43%, and 5.28%, respectively (P = .1884). Univariate analysis of factors potentially associated with IBTR indicated that negative estrogen receptor status was the only variable associated with IBTR among patients with invasive breast cancer (odds ratio [OR], 4.01; P = .0003). Larger tumor size was associated with a greater risk of distant metastasis (OR, 3.05; P = .0001). Among patients with ductal carcinoma in situ, only age <50 years and close-positive margins were associated with IBTR (OR, 1.12 [P = .0079] and OR, 7.81 [P = .0131], respectively). The ASTRO CS groupings did not differentiate a subset of patients with a significantly worse rate of IBTR when they were treated with the MammoSite breast brachytherapy catheter to deliver APBI.

Factors Associated with Skin Telangectasias and Cosmetic Outcome in Patients Treated on the American Society of Breast Surgeons MammoSite Registry Trial

Cosmetic outcome is an important endpoint of breast conservation. The MammoSite brachytherapy applicator has an associated incidence of telangectasias. The ASBS Registry Trial is examined for factors impacting telangectasia formation and cosmetic results.