Abstract P1-15-06: Impact of serial biopsies in triple-negative breast cancer patients receiving neoadjuvant systemic therapy
Authors: Yam C , Raghavendra A , Hess KR , Adrada BE , Candelaria RP , Damodaran S , Gilcrease MZ , Helgason T , Hortobagyi GN , Huo L , Layman RM , Lim B , Litton JK , Mittendorf EA , Murthy RK , Piwnica-Worms H , Rauch GM , Santiago L , Symmans F , Thompson AM , Tripathy D , Ueno NT , Valero V , Barcenas CH , Moulder SL , Yang W 
Published: May 2019

Background: Serial biopsies (bx) of triple-negative breast cancer (TNBC) in the curative neoadjuvant setting provides critical information on dynamic changes in the tumor in response to neoadjuvant systemic therapy (NAST) and can help inform the development of novel therapeutic strategies. However, neoplastic seeding following image guided breast bx has previously been reported in TNBC, raising concerns that serial bx may worsen clinical outcomes. Thus, we sought to determine if serial bx were associated with poorer clinical outcomes (using rates of pathologic complete response [pCR]) in TNBC pts receiving NAST.

Methods: We identified 370 TNBC pts who received NAST at MD Anderson Cancer Center from 2011-2017. 200 pts did not have any research bx done (controls) on the index breast carcinoma and 170 pts had at least one research bx done (cases) on the index breast carcinoma as part of the prospective molecular triaging ARTEMIS trial. Baseline characteristics were compared between cases and controls using the Student t-test, Wilcoxon Rank Sum test or Fisher's exact test as appropriate. Univariable and multivariable logistic regression was used to determine if rates of pCR following NAST were significantly different between cases and controls.

Results: Demographic characteristics demonstrate no significant differences (Table). However, cases were more likely to have received an anthracycline (99% vs 96%, p=0.02) and a targeted agent (22% vs 0%, p&lt;0.01) in the neoadjuvant setting as part of the ARTEMIS trial. A total of 211 bx of the index carcinoma were performed in the 200 controls, of whom, 6% (11/200) had a second bx of the index carcinoma done solely for diagnostic purposes. In contrast, a total of 407 bx of the index carcinoma were performed in the 170 cases (mean: 2.4 biopsies). Of the 407 bx done in the 170 cases, 58% (237/407) were done for research purposes. The pCR rate in controls and cases was 48% (96/200, 95% confidence interval [CI]: 41-55%) and 42% (72/170, 95% CI: 35-50%), respectively. The odds of pCR following NAST were not significantly different between controls and cases on both univariable (odds ratio [OR]: 0.80; 95% CI: 0.53-1.20, p=0.28) and multivariable logistic regression (adjusted OR: 0.94; 95% CI: 0.58-1.51; p=0.79).

Conclusion: This is the first study examining the impact of serial bx on clinical outcomes in TNBC pts in the curative neoadjuvant setting. Our data suggest that research bx in this setting do not compromise rates of pCR.

Baseline and Treatment CharacteristicsCharacteristicControls (n=200)Cases (n=170)p valueMean age - years (standard deviation [SD])52 (12)53 (12)0.54Ethnicity   White – n (%)113 (57)115 (68)0.09Black – n (%)48 (24)29 (17) Other – n (%)39 (20)26 (15) Mean tumor size – cm (SD)3.2 (1.4)3.3 (1.7)0.62T stage – n (%)   T134 (17)35 (21)0.96T2145 (73)111 (65) T314 (7)17 (10) T47 (4)7 (4) N stage – n (%)   N0101 (51)89 (52)0.83N170 (35)55 (32) N27 (4)6 (4) N322 (11)20 (12) Stage – n (%)   I19 (10)21 (12)0.74II140 (70)113 (66) III41 (21)36 (21) Grade – n (%)   19 (5)00.14227 (14)22 (13) 3164 (82)148 (87) Neoadjuvant therapy – n (%)   Anthracycline191 (96)169 (99)0.02Taxane199 (100)166 (98)0.18Platinum23 (12)23 (14)0.63Targeted agent037 (22)&lt;0.01

Citation Format: Yam C, Raghavendra A, Hess KR, Adrada BE, Candelaria RP, Damodaran S, Gilcrease MZ, Helgason T, Hortobagyi GN, Huo L, Layman RM, Lim B, Litton JK, Mittendorf EA, Murthy RK, Piwnica-Worms H, Rauch GM, Santiago L, Symmans F, Thompson AM, Tripathy D, Ueno NT, Valero V, Barcenas CH, Moulder SL, Yang W. Impact of serial biopsies in triple-negative breast cancer patients receiving neoadjuvant systemic therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-06.