De-escalating Surgery Among Patients with HER2 + and Triple Negative Breast Cancer

Omission of breast surgery in selected breast cancer patients with excellent response to neoadjuvant systemic therapy

Modern neoadjuvant systemic therapy (NST) can result in high pathologic complete response rates (pCR) in triple negative (TN) and human epidermal growth factor receptor 2 positive (HER2+) breast cancer. The role of surgery is, therefore, being reconsidered in this rapidly evolving field. This report presents oncological outcomes of seven patients with TN or HER2+ breast cancer, with exceptional response to NST, and a post-NST image-guided vacuum assisted biopsy showing no residual disease (ypT0), who opted not to have breast surgery. The median age was 49 (IQR 36-61) years and the median tumour size at diagnosis was 50 (IQR 16-65) mm. All patients received breast radiotherapy and continued adjuvant systemic therapies as appropriate. At a median follow-up of 67 (IQR 61-77) months, all patients were alive and free of disease. This small case series supports the need for further research in 'exceptional responders' to provide safe, individualized patient-centred care.

Real de-escalation or escalation in disguise?

The past two decades have seen an unprecedented trend towards de-escalation of surgical therapy in the setting of early BC, the most prominent examples being the reduction of re-excision rates for close surgical margins after breast-conserving surgery and replacing axillary lymph node dissection by less radical procedures such as sentinel lymph node biopsy (SLNB). Numerous studies confirmed that reducing the extent of surgery in the upfront surgery setting does not impact locoregional recurrences and overall outcome. In the setting of primary systemic treatment, there is an increased use of less invasive staging strategies reaching from SLNB and targeted lymph node biopsy (TLNB) to targeted axillary dissection (TAD). Omission of any axillary surgery in the presence of pathological complete response in the breast is currently being investigated in clinical trials. On the other hand, concerns have been raised that surgical de-escalation might induce an escalation of other treatment modalities such as radiation therapy. Since most trials on surgical de-escalation did not include standardized protocols for adjuvant radiotherapy, it remains unclear, whether the effect of surgical de-escalation was valid in itself or if radiotherapy compensated for the decreased surgical extent. Uncertainties in scientific evidence may therefore lead to escalation of radiotherapy in some settings of surgical de-escalation. Further, the increasing rate of mastectomies including contralateral procedures in patients without genetic risk is alarming. Future studies of locoregional treatment strategies need to include an interdisciplinary approach to integrate de-escalation approaches combining surgery and radiotherapy in a way that promotes optimal quality of life and shared decision-making.

Accuracy of core biopsy image-guided post-neoadjuvant chemotherapy breast to predict pathologic complete response

Background. Achieving a pathologic complete response (pCR) after neoadjuvant systemic therapy (NST) is a predictive factor for improving disease free and overall survival. In triple negative (TN) and HER2-positive breast cancer (BC), the pCR rate exceeds 60 %. Patients with TN and HER2-positive BC who demonstrate an excellent response to NST are like­ly ideal candidates for downsizing surgery. The condition for reducing the volume of surgical intervention is a reliable determination of pathologic complete response using instrumental imaging and biopsy methods.

Aim. To further assess the accuracy of post-NST image-guided biopsy to predict pCR.

Materials and methods. Sixty one patients with T1-3N0-3 triple negative or HER2-positive BC receiving NST in the Department of Breast Tumors of the NMRC of Oncology named after N.N. Petrov in the period from 2017 to 2019 were enrolled in this single-center retrospective trial. Patients underwent ultrasound-guided core-biopsy of the initial breast tumor region before surgery. Findings were compared with findings on pathologic evaluation of surgical specimens to determine the performance of biopsy in predicting pCR after NST.

Results. After neoadjuvant systemic therapy, clinical partial response (cPR) was diagnosed in 47 (77 %) patients, clinical complete response (cCR) in 14 (23 %) patients. pCR in the core-biopsy tissue and surgical material was achieved in 46 (75.4 %) and 37 (60.7 %), respectively. Performance of image-guided core-biopsy: sensitivity 100 % (95 % confldence interval (CI) 90.51-100), specificity 62.5 % (95 % CI 40.59-81.20), false-negative rate (FNR) 0 %, positive-pre­dictive value (PPV) 75.00 % (95 % CI 59.46-85.99), negative predictive value (NPV) 100.00 %.

Conclusion. This retrospective trial showed that ultrasound-guided core biopsies are accurate enough to identify breast pCR in patients with triple-negative or HER2-positive BC with good response after NST (FNR 0 %). Based on these results, a prospective clinical trial has commenced in which breast surgery is omitted in patients with a breast pCR after NST according to image-guided biopsy.