A single-cell RNA expression atlas of normal, preneoplastic and tumorigenic states in the human breast.

To examine global changes in breast heterogeneity across different states, we determined the single-cell transcriptomes of > 340,000 cells encompassing normal breast, preneoplastic BRCA1+/- tissue, the major breast cancer subtypes, and pairs of tumors and involved lymph nodes. Elucidation of the normal breast microenvironment revealed striking changes in the stroma of post-menopausal women. Single-cell profiling of 34 treatment-naive primary tumors, including estrogen receptor (ER)+ , HER2+ , and triple-negative breast cancers, revealed comparable diversity among cancer cells and a discrete subset of cycling cells. The transcriptomes of preneoplastic BRCA1+/- tissue versus tumors highlighted global changes in the immune microenvironment. Within the tumor immune landscape, proliferative CD8+ T cells characterized triple-negative and HER2+ cancers but not ER+ tumors, while all subtypes comprised cycling tumor-associated macrophages, thus invoking potentially different immunotherapy targets. Copy number analysis of paired ER+ tumors and lymph nodes indicated seeding by genetically distinct clones or mass migration of primary tumor cells into axillary lymph nodes. This large-scale integration of patient samples provides a high-resolution map of cell diversity in normal and cancerous human breast.

Multicentre evaluation of magnetic technology for localisation of non-palpable breast lesions and targeted axillary nodes.

BACKGROUND: Magseed technology is a recently introduced localisation technique for impalpable breast lesions with possible advantages over traditional techniques. These include improved theatre logistics, flexibility in incision placement and improved patient experience. This multicentre study evaluates the experience of introducing Magseed technology into routine surgical practice. METHODS: A prospective multicentre study of Magseed localised procedures was performed. Insertion data were recorded by the radiologist including lesion characteristics and Magseed insertion accuracy. The surgical team recorded time from insertion to operation, operating time and surgical satisfaction. Pathology results were reviewed for specimen weight and margins. RESULTS: Between February 2019 and June 2020, 100 patients were enrolled. Magseed localised procedures included 18 excisional biopsies, 23 wide local excisions (WLE), 50 WLE with axillary surgery and four cases of Magseed localised breast WLE with Magseed localised axillary surgery. There were three therapeutic mammoplasties and two cases of Magseed localised targeted axillary node dissection alone. A total of 90% of Magseeds were radiologically placed within 5 mm of the target lesion/node. Time between incision and specimen removal was 17 min (range 6-40 min). All breast and axillary Magseeds were successfully identified and retrieved during surgery. The target lesion was identified in the specimen in all cases. A total of 10% of cases required further surgery for pathologically positive margins. Overall, surgeons reported that Magseed localisation was "easy" or "very easy" in 77% of cases. CONCLUSION: Magseed is a reliable, safe and accurate surgical technique that provides logistical advantages and flexibility of surgical approach. The method was well-accepted by all users.

The iPrevent Online Breast Cancer Risk Assessment and Risk Management Tool: Usability and Acceptability Testing.

BACKGROUND: iPrevent estimates breast cancer (BC) risk and provides tailored risk management information. OBJECTIVE: The objective of this study was to assess the usability and acceptability of the iPrevent prototype. METHODS: Clinicians were eligible for participation in the study if they worked in primary care, breast surgery, or genetics clinics. Female patients aged 18-70 years with no personal cancer history were eligible. Clinicians were first familiarized with iPrevent using hypothetical paper-based cases and then actor scenarios; subsequently, they used iPrevent with their patients. Clinicians and patients completed the System Usability Scale (SUS) and an Acceptability questionnaire 2 weeks after using iPrevent; patients also completed measures of BC worry, anxiety, risk perception, and knowledge pre- and 2 weeks post-iPrevent. Data were summarized using descriptive statistics. RESULTS: The SUS and Acceptability questionnaires were completed by 19 of 20 clinicians and 37 of 43 patients. Usability was above average (SUS score >68) for 68% (13/19) clinicians and 76% (28/37) patients. The amount of information provided by iPrevent was reported as "about right" by 89% (17/19) clinicians and 89% (33/37) patients and 95% (18/19) and 97% (36/37), respectively, would recommend iPrevent to others, although 53% (10/19) clinicians and 27% (10/37) patients found it too long. Exploratory analyses suggested that iPrevent could improve risk perception, decrease frequency of BC worry, and enhance BC prevention knowledge without changing state anxiety. CONCLUSIONS: The iPrevent prototype demonstrated good usability and acceptability. Because concerns about length could be an implementation barrier, data entry has been abbreviated in the publicly available version of iPrevent.

RANK ligand as a potential target for breast cancer prevention in BRCA1-mutation carriers.

Individuals who have mutations in the breast-cancer-susceptibility gene BRCA1 (hereafter referred to as BRCA1-mutation carriers) frequently undergo prophylactic mastectomy to minimize their risk of breast cancer. The identification of an effective prevention therapy therefore remains a 'holy grail' for the field. Precancerous BRCA1(mut/+) tissue harbors an aberrant population of luminal progenitor cells, and deregulated progesterone signaling has been implicated in BRCA1-associated oncogenesis. Coupled with the findings that tumor necrosis factor superfamily member 11 (TNFSF11; also known as RANKL) is a key paracrine effector of progesterone signaling and that RANKL and its receptor TNFRSF11A (also known as RANK) contribute to mammary tumorigenesis, we investigated a role for this pathway in the pre-neoplastic phase of BRCA1-mutation carriers. We identified two subsets of luminal progenitors (RANK(+) and RANK(-)) in histologically normal tissue of BRCA1-mutation carriers and showed that RANK(+) cells are highly proliferative, have grossly aberrant DNA repair and bear a molecular signature similar to that of basal-like breast cancer. These data suggest that RANK(+) and not RANK(-) progenitors are a key target population in these women. Inhibition of RANKL signaling by treatment with denosumab in three-dimensional breast organoids derived from pre-neoplastic BRCA1(mut/+) tissue attenuated progesterone-induced proliferation. Notably, proliferation was markedly reduced in breast biopsies from BRCA1-mutation carriers who were treated with denosumab. Furthermore, inhibition of RANKL in a Brca1-deficient mouse model substantially curtailed mammary tumorigenesis. Taken together, these findings identify a targetable pathway in a putative cell-of-origin population in BRCA1-mutation carriers and implicate RANKL blockade as a promising strategy in the prevention of breast cancer.