Abstract P5-16-30: Feasibility trial for identification of patients for eliminating breast cancer surgery following neoadjuvant systemic therapy

Background: Contemporary improved neoadjuvant systemic therapy (NST) for breast cancer may result in a pathologic complete response (pCR) in up to 60% of patients (pts) yet imaging alone has a poor negative predictive value to determine which pts might be spared surgery . This study was designed to evaluate the hypothesis that percutaneous image guided biopsy after NST can accurately identify patients who may forgo surgery. Methods: Prospective single-center IRB approved study of 34 pts with clinical T1-3 N0-3 triple-negative (TN, n=23) or HER2-positive (n=11) invasive ductal cancer who received standard NST and consented for ultrasound/mammography guided vacuum-assisted core biopsy (VACB) and fine-needle aspiration (FNA) biopsy prior to standard surgery. Main outcome measures included accuracy, false-negative rate (FNR), and negative predictive value of image guided biopsy in predicting residual disease after NST. Breast pCR was defined as no residual DCIS or invasive disease. Final biopsy showing atypia and/or suspicion of residual disease was recorded as positive. Results : Median initial maximum tumor size based on imaging and physical exam was 3 cm (1.2-7 cm) and 47.1% had FNA/core biopsy proved nodal metastases. Final median maximum residual tumor size after NST was 0.9 cm (0-4.2 cm) with 94.1% having no palpable abnormality. Median number of VACB (9G) removed following NST was 10 (4-14) and was performed by stereotactic (67.6%) or ultrasound (32.4%) guidance. Overall, a breast pCR occurred in 18 (52.9%) of pts and breast pathologic response was concordant with nodal pathologic response in 33 (97%) of pts (1 pt with a breast pCR had 1/15 nodes with metastases). Overall, VACB combined with FNA following NST had a 100% (95% CI 89.7-100) accuracy, 0% FNR (95% CI 0-20.6), and 100% (95% CI 81.5-100) negative predictive value for determination of residual breast disease. Grade 1 adverse events which resolved from biopsy (bleeding, hematoma, bruising) occurred in 6 pts (17.6%). Conclusions : High rates of pCR among pts with TN/HER2-positive breast cancer receiving NST occur in a significant proportion of pts. The use of image guided VACB/FNA can identify pts after NST where significant residual disease is unlikely. Based on these results, an IRB approved clinical trial will shortly commence for pts with T1-2 TN/HER2-positive breast cancer with documented image guided biopsy proved pCR after NST to be followed by standard definitive whole-breast radiotherapy without surgery. Background: Contemporary improved neoadjuvant systemic therapy (NST) for breast cancer may result in a pathologic complete response (pCR) in up to 60% of patients (pts) yet imaging alone has a poor negative predictive value to determine which pts might be spared surgery . This study was designed to evaluate the hypothesis that percutaneous image guided biopsy after NST can accurately identify patients who may forgo surgery. Methods: Prospective single-center IRB approved study of 34 pts with clinical T1-3 N0-3 triple-negative (TN, n=23) or HER2-positive (n=11) invasive ductal cancer who received standard NST and consented for ultrasound/mammography guided vacuum-assisted core biopsy (VACB) and fine-needle aspiration (FNA) biopsy prior to standard surgery. Main outcome measures included accuracy, false-negative rate (FNR), and negative predictive value of image guided biopsy in predicting residual disease after NST. Breast pCR was defined as no residual DCIS or invasive disease. Final biopsy showing atypia and/or suspicion of residual disease was recorded as positive. Results : Median initial maximum tumor size based on imaging and physical exam was 3 cm (1.2-7 cm) and 47.1% had FNA/core biopsy proved nodal metastases. Final median maximum residual tumor size after NST was 0.9 cm (0-4.2 cm) with 94.1% having no palpable abnormality. Median number of VACB (9G) removed following NST was 10 (4-14) and was performed by stereotactic (67.6%) or ultrasound (32.4%) guidance. Overall, a breast pCR occurred in 18 (52.9%) of pts and breast pathologic response was concordant with nodal pathologic response in 33 (97%) of pts (1 pt with a breast pCR had 1/15 nodes with metastases). Overall, VACB combined with FNA following NST had a 100% (95% CI 89.7-100) accuracy, 0% FNR (95% CI 0-20.6), and 100% (95% CI 81.5-100) negative predictive value for determination of residual breast disease. Grade 1 adverse events which resolved from biopsy (bleeding, hematoma, bruising) occurred in 6 pts (17.6%). Conclusions : High rates of pCR among pts with TN/HER2-positive breast cancer receiving NST occur in a significant proportion of pts. The use of image guided VACB/FNA can identify pts after NST where significant residual disease is unlikely. Based on these results, an IRB approved clinical trial will shortly commence for pts with T1-2 TN/HER2-positive breast cancer with documented image guided biopsy proved pCR after NST to be followed by standard definitive whole-breast radiotherapy without surgery. Citation Format: Kuerer HM, Rauch GM, Krishnamurthy S, Adrada BE, Caudle AS, DeSnyder SM, Santiago L, Lucci A, Hobbs BP, Gilcrease M, Hwang R, Candelaria RP, Chavez Mac-Gregor M, Arribas E, Moseley T, Teshome M, Miggins MV, Smith BD, Valero V, Hunt KK, Yang WT. Feasibility trial for identification of patients for eliminating breast cancer surgery following neoadjuvant systemic therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-30.