Summary Triple-negative breast cancer is a heterogeneous disease and specific therapies have not been available for a long time. Therefore, conventional chemotherapy is still considered the clinical ...state of the art. Different subgroups of triple-negative breast cancer have been identified on the basis of protein expression, mRNA signatures, and genomic alterations. Important elements of triple-negative breast cancer biology include high proliferative activity, an increased immunological infiltrate, a basal-like and a mesenchymal phenotype, and deficiency in homologous recombination, which is in part associated with loss of BRCA1 or BRCA2 function. A minority of triple-negative tumours express luminal markers, such as androgen receptors, and have a lower proliferative activity. These biological subgroups are overlapping and currently cannot be combined into a unified model of triple-negative breast cancer biology. Nevertheless, the molecular analysis of this disease has identified potential options for targeted therapeutic intervention. This has led to promising clinical strategies, including modified chemotherapy approaches targeting the DNA damage response, angiogenesis inhibitors, immune checkpoint inhibitors, or even anti-androgens, all of which are being evaluated in phase 1–3 clinical studies. This Series paper focuses on the most relevant clinical questions, summarises the results of recent clinical trials, and gives an overview of ongoing studies and trial concepts that will lead to a more refined therapy for this tumour type.
Summary Background The optimum timing of sentinel-lymph-node biopsy for breast cancer patients treated with neoadjuvant chemotherapy is uncertain. The SENTINA (SENTinel NeoAdjuvant) study was ...designed to evaluate a specific algorithm for timing of a standardised sentinel-lymph-node biopsy procedure in patients who undergo neoadjuvant chemotherapy. Methods SENTINA is a four-arm, prospective, multicentre cohort study undertaken at 103 institutions in Germany and Austria. Women with breast cancer who were scheduled for neoadjuvant chemotherapy were enrolled into the study. Patients with clinically node-negative disease (cN0) underwent sentinel-lymph-node biopsy before neoadjuvant chemotherapy (arm A). If the sentinel node was positive (pN1), a second sentinel-lymph-node biopsy procedure was done after neoadjuvant chemotherapy (arm B). Women with clinically node-positive disease (cN+) received neoadjuvant chemotherapy. Those who converted to clinically node-negative disease after chemotherapy (ycN0; arm C) were treated with sentinel-lymph-node biopsy and axillary dissection. Only patients whose clinical nodal status remained positive (ycN1) underwent axillary dissection without sentinel-lymph-node biopsy (arm D). The primary endpoint was accuracy (false-negative rate) of sentinel-lymph-node biopsy after neoadjuvant chemotherapy for patients who converted from cN1 to ycN0 disease during neoadjuvant chemotherapy (arm C). Secondary endpoints included comparison of the detection rate of sentinel-lymph-node biopsy before and after neoadjuvant chemotherapy, and also the false-negative rate and detection rate of sentinel-lymph-node biopsy after removal of the sentinel lymph node. Analyses were done according to treatment received (per protocol). Findings Of 1737 patients who received treatment, 1022 women underwent sentinel-lymph-node biopsy before neoadjuvant chemotherapy (arms A and B), with a detection rate of 99·1% (95% CI 98·3–99·6; 1013 of 1022). In patients who converted after neoadjuvant chemotherapy from cN+ to ycN0 (arm C), the detection rate was 80·1% (95% CI 76·6–83·2; 474 of 592) and false-negative rate was 14·2% (95% CI 9·9–19·4; 32 of 226). The false-negative rate was 24·3% (17 of 70) for women who had one node removed and 18·5% (10 of 54) for those who had two sentinel nodes removed (arm C). In patients who had a second sentinel-lymph-node biopsy procedure after neoadjuvant chemotherapy (arm B), the detection rate was 60·8% (95% CI 55·6–65·9; 219 of 360) and the false-negative rate was 51·6% (95% CI 38·7–64·2; 33 of 64). Interpretation Sentinel-lymph-node biopsy is a reliable diagnostic method before neoadjuvant chemotherapy. After systemic treatment or early sentinel-lymph-node biopsy, the procedure has a lower detection rate and a higher false-negative rate compared with sentinel-lymph-node biopsy done before neoadjuvant chemotherapy. These limitations should be considered if biopsy is planned after neoadjuvant chemotherapy. Funding Brustkrebs Deutschland, German Society for Senology, German Breast Group.
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