Babiera, GV

LBA513 Background: Neoadjuvant aromatase inhibitor (AI) therapy is a rational and effective approach to improving the breast conservation surgery (BCS) rate for postmenopausal patients with large, estrogen receptor (ER) rich breast cancers. Barriers to adopting this strategy include lack of experience in this management approach in the US and uncertainty regarding the comparative effectiveness of the three approved aromatase inhibitors for this indication. Methods: ACOSOG Z1031 is a multicenter, open-label, neoadjuvant phase III screening study that randomized postmenopausal women with clinical stage II/III ER rich (Allred score 6-8) breast cancer to 16 weeks of either exemestane (EXE) 25 mg daily, letrozole (LET) 2.5 mg daily, or anastrozole (ANA) 1 mg daily. At baseline study participants were either marginal for BCS (MBCS), candidates for mastectomy only (MO), or inoperable (IO). Planned enrolment was 125 patients per arm in order that the likelihood of the treatment with the “best” 16-week clinical response rate (based on caliper measurements) by WHO criteria (cRR) was included among the subset of treatments with “similar” cRR (90% power). Secondary endpoints included: extent of surgery, radiologic and pathologic response rates. Results: From 4/1/2006 to 10/1/2009, 377 postmenopausal women with clinical stage II or III ER rich breast cancer were enrolled. 374 women began treatment and were included in an intent-to-treat analysis. Median age was 66 yrs (range: 43-90 yrs), Median tumor size was 4.0 cm (range: 2-13 cm). The 16-week cRR was 60.5% (95%CI: 51.3-69.1%) for EXE; 70.9% (95% CI: 62.2-78.6%) for LET, and 66.7% (95% CI: 57.6-74.9%) for ANA. Seventeen patients did not have surgery due to refusal (12 pts), progression (3 pts) or other medical conditions (2 pts). The BCS rate was 78% (163/207) in MBCS group; 42% (77/163) in MO group; and 75% in IO group (3/4). Surgeons made the decisions regarding procedure choice 75% of the time in both the MBCS and the MO categories. Conclusions: This large multicenter screening trial selected non-steroidal AIs for further development due to their higher observed cRR. The study demonstrates that high response and breast conservation rates and low rates of disease progression can be achieved through patient selection based on high ER expression. We are currently refining our approach for early detection of poor response to AIs through an assessment of the tumor Ki67 proliferation index at 2 to 4 weeks (Z1031 Cohort B). [Table: see text]

Abstract Purpose: Emerging data from cooperative group trials suggests that not all patients with a positive SLN require completion axillary lymph node dissection (ALND). The controversy regarding who will benefit from additional nodal clearance continues, suggesting a need for improved tools to predict non-SLN involvement. We hypothesized that the size of a SLN metastasis evaluated as a continuous variable would be an important predictor of non-SLN involvement. The goal of this study was to determine clinicopathologic factors including SLN metastasis size that predicted non-SLN involvement and to use these factors to construct an improved predictive nomogram. Methods: Using a prospective database, we identified 509 patients with invasive breast cancer from 1996 - 2007 with a positive SLN who underwent ALND. Patients receiving neoadjuvant therapy were excluded. Clinicopathologic data including age, primary tumor size, presence of multifocal disease, histology (invasive ductal vs. invasive lobular vs. mixed invasive), tumor grade, estrogen receptor, progesterone receptor, and HER2/neu status, presence of lymphovascular invasion (LVI), the number of SLNs identified, number of positive SLNs, the maximum SLN metastasis size and the presence of extranodal extension were recorded. For SLNs described only as containing isolated tumor cells, size was recorded as 0.1 mm. Univariate and multivariate logistic regression analyses were performed to identify factors predictive of positive non-SLNs. Using these variables, a nomogram was constructed and subsequently validated using an external cohort of 464 patients. Results: On univariate analysis, the following factors were predictive of positive non-SLNs: number of SLN identified (p<.001), number of positive SLN (p<.001), maximum SLN metastasis size (p<.001), extranodal extension (p<.001), primary tumor size (p=.001), LVI (p=.019) and histology (p=.034). On multivariate analysis, all factors remained significant at the 5% level except LVI. A nomogram was created using these variables. When applied to an external cohort, the nomogram was accurate and discriminating with an area under the receiver operating characteristic curve of .73 (95% CI: .68 - .77). Conclusions: SLN metastasis size is predictive for identifying additional disease in the axilla. These data have been incorporated into a nomogram that accurately predicts the likelihood of having additional, non-SLN metastasis suggesting that routine reporting of the SLN metastasis size would assist with clinical decision making regarding the need to perform a completion ALND. Figures available in online version. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD06-08.