Abstract P5-16-14: NOSTRA PRELIM: A non randomised pilot study designed to assess the ability of image guided core biopsies to detect residual disease in patients with early breast cancer who have received neoadjuvant chemotherapy to inform the design of a planned trial

Abstract

Abstract BACKGROUND Patients receiving neoadjuvant chemotherapy for breast cancer go on to have surgery regardless of their response. Women with HER-2 positive ER negative tumours (7.5% of all operable breast cancers in the UK) respond so well to neoadjuvant treatment with dual anti-HER2 therapy in combination with chemotherapy that pathological complete response rates of 80% can be achieved. This means that for patients receiving this treatment surgery is being performed to remove a cancer that isn't there in the large majority. A study is planned in the UK (NOSTRA ) to assess if it is feasible to treat patients with HER-2 positive ER negative breast cancer who achieve a pCR after neoadjuvant chemotherapy with trastuzmab and pertuzumab with radiotherapy alone. The first phase of the trial will be a feasibility study commencing in 2017 where all patients will have image guided tumour bed biopsies post treatment and all patients will have surgery. If the group of patients where a pCR is achieved can be accurately identified then a phase III trial randomising to surgery and radiotherapy or radiotherapy alone is planned. The NOSTRA PRELIM study reported here assessed the ability of post neoadjuvant chemotherapy tumour bed biopsies to detect residual disease to provide experience to inform the much larger NOSTRA feasibility trial biopsy protocol. METHODS 23 consecutive patients with operable primary breast cancer scheduled for neoadjuvant chemotherapy were approached to take part in the study and 20 gave consent. All 20 patients had a clip inserted into the tumour bed under ultrasound(USS) guidance at diagnosis as is standard procedure. The number of cores taken ranged from 2-6. The median number of biopsies was 4 Tumour size range at diagnosis was 15-61mm with USS. All received neo-adjuvant chemotherapy and those who were Her2 positive received neoadjuvant trastusumab. At completion all patients had USS guided tumour bed biopsy. They then went on to have surgery, after which pathology was assessed and an RCB score calculated for each patient. For this study patients all tumour types were included as non pCR outcomes were required to determine accuracy and inform changes to the biopsy protocol for future use. RESULTS Only 2 patients in this study achieved a pCR Residual disease was correctly identified in 16/20 patients. Four patients had no tumour in their post treatment biopsies but had small residual invasive tumour at surgery. The size of residual disease in these patients ranged from 0.5 -9mm and all these patients had 3 core biopsies. One patient had negative post treatment biopsies and a PCR of their invasive tumour. This patient had a diagnostic biopsy that confirmed separate area of DCIS several centimetres from the invasive component. This area did not undergo post treatment tumour bed biopsies (although both areas were clipped at diagnosis). CONCLUSION A protocol for biopsy in the upcoming NOSTRA feasibility study has been designed to both take more biopsies and sample a larger area of the tumour bed in order minimise the false negative rate. Citation Format: Francis A, Herring K, Molyneux R, Jafri M, Trivedi S, Shaaban A, Rea DW. NOSTRA PRELIM: A non randomised pilot study designed to assess the ability of image guided core biopsies to detect residual disease in patients with early breast cancer who have received neoadjuvant chemotherapy to inform the design of a planned trial [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 P5-16-14.