Abstract P5-22-09: Feasibility study to diagnose pathological complete response by neoadjuvant chemotherapy in breast cancer adding core needle biopsy (KBOG1301 supported by JONIE)
Authors: Narui K , Ishikawa T , Hasegawa Y , Kaise H , Kawate T , Yamada K , Suzuki Y , Niikura N , Kohno N , Kimoto T , Sugae S , Yamada A , Kosaka Y , Miyashita M , Okamura T , Shimizu D , Tanino H , Sakamaki K , Tokuda Y 
Published: February 2018

Background: Neoadjuvant chemotherapy (NAC) for breast cancer has been improved and pathological complete response (pCR) achieved in about 50% of Her2 positive tumor and over 30% of triple negative tumor. It is possible that not to perform surgery if pCR is diagnosed accurately. This study was performed to examine diagnostic ability of core needle biopsy (CNB) to detect pCR by NAC. (Study registry number: UMIN000012035)

Methods: In this multicenter study, we registered histologically proved breast cancer patients who were diagnosed as clinical complete response (cCR) after NAC. The cCR was diagnosed by contrast-enhanced magnetic resonance imaging (MRI) after NAC by radiologists in each facility. Regimens of NAC were not specified by study protocol. A clip marker was not placed in the tumor before NAC. At the operating table, ultrasound-guided CNB is performed before starting the surgery. The CNB was performed with 14 gauge needle without vacuum assistance and requiring three biopsy specimens. The concordance of pathological results between a core needle biopsy and a surgical specimen is examined by pathologists at each facility. The pathological diagnosis was categorized as i) no carcinoma (pCR), ii) carcinoma in situ (CIS) and iii) invasive carcinoma.

Results: The study included 86 women from 10 facilities, accrued from December 2013 to March 2017. Median age was 53.5 (31-75) years and median tumor size before NAC was 2.3 (0.9-7.3) cm. Estrogen receptor was positive in 32 (37%). HER2 was positive in 40 (47%). The clinical stage before NAC was stage I 19 (22%), II 48 (56%), III 16 (19%) and IV 3 (3%). All cases were administered cytotoxic agents. Both anthracycline and taxane were given in 70 cases (81%), and trastuzumab was administered in 35 (41%) cases. As for breast surgery, partial resection was performed in 53 cases (62%), whereas 33 cases (38%) underwent mastectomy. Pathological examination on surgical specimen revealed pCR (i) in 41 cases (48%), CIS (ii) in 17 cases (20%) and invasive carcinoma (iii) in 28 cases (32%). Results of pathology of CNB and surgical specimens are shown in table 1.

Table 1. Pathological diagnosis of CNB and surgical specimens Surgical specimen  No carcinoma (pCR)Residual carcinomaTotalCNBNo carcinoma (pCR)41 (NPV=63%, spec.=100%)24 (FNR=53%, 14 were CIS)65 (76%) Residual carcinoma021 (PPV=100%, sens.=47%)21 (24%)Total41 (48%)45 (52%)86 (100%)CNB: core needle biopsy, FNR: false-negative rate, CIS: carcinoma in situ, NPV: negative predictive value, PPV: positive predictive value, sens.: sensitivity, spec.: specificity.

The kappa value was 0.455 which was not enough for accurate diagnosis. In 24 discordant cases, residual tumor was found in surgical specimen but not in CNB, residual disease was CIS in 14 cases.

Conclusions: Up to 10% false negative rate of pCR may allow us to proceed to an observational study without performing surgery.This study revealed that the ultrasound-guided CNB for cCR cases by MRI was not accurate enough to omit surgery. Thus, imaging diagnosis and biopsy methods need to be improved. However, it is still possible to consider because the post-operative radiotherapy may compensate for surgery in cases with CIS after NAC.

Citation Format: Narui K, Ishikawa T, Hasegawa Y, Kaise H, Kawate T, Yamada K, Suzuki Y, Niikura N, Kohno N, Kimoto T, Sugae S, Yamada A, Kosaka Y, Miyashita M, Okamura T, Shimizu D, Tanino H, Sakamaki K, Tokuda Y. Feasibility study to diagnose pathological complete response by neoadjuvant chemotherapy in breast cancer adding core needle biopsy (KBOG1301 supported by JONIE) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-22-09.