Pain Management in Breast Surgery: Recommendations of a Multidisciplinary Expert Panel-The American Society of Breast Surgeons.

Opioid overdose accounted for more than 47,000 deaths in the United States in 2018. The risk of new persistent opioid use following breast cancer surgery is significant, with up to 10% of patients continuing to fill opioid prescriptions one year after surgery. Over prescription of opioids is far too common. A recent study suggested that up to 80% of patients receiving a prescription for opioids post-operatively do not need them (either do not fill the prescription or do not use the medication). In order to address this important issue, The American Society of Breast Surgeons empaneled an inter-disciplinary committee to develop a consensus statement on pain control for patients undergoing breast surgery. Representatives were nominated by the American College of Surgeons, the Society of Surgical Oncology, The American Society of Plastic Surgeons, and The American Society of Anesthesiologists. A broad literature review followed by a more focused review was performed by the inter-disciplinary panel which was comprised of 14 experts in the fields of breast surgery, anesthesiology, plastic surgery, rehabilitation medicine, and addiction medicine. Through a process of multiple revisions, a consensus was developed, resulting in the outline for decreased opioid use in patients undergoing breast surgery presented in this manuscript. The final document was reviewed and approved by the Board of Directors of the American Society of Breast Surgeons.

Diabetes Mellitus and Metformin Are Not Associated With Breast Cancer Pathologic Complete Response.

BACKGROUND: Metformin use has been linked to pathologic complete response (pCR) following neoadjuvant chemotherapy for several malignancies. We aimed to investigate the association of diabetes mellitus (DM) and metformin use with pCR in breast cancer. MATERIALS AND METHODS: All breast cancer patients who received neoadjuvant chemotherapy during June 2013-October 2016 at two academic medical centers were identified. A retrospective cohort study evaluated patients who did and did not achieve pCR. Multivariable logistic regression identified independent predictors of pCR, specifically looking at metformin use and DM. RESULTS: The study group included 351 breast cancer patients, with 90 (25.6%) achieving pCR after neoadjuvant chemotherapy. The rate of DM did not differ between those with and without pCR, nor did the rate of metformin use. Multivariable logistic regression identified HER2-positive tumors and smaller preoperative tumor size as predictors of pCR. The estrogen receptor (ER) positivity was associated with an absence of pCR. Importantly, neither DM nor metformin use was predictive of pCR. CONCLUSIONS: This study by the two institutions supports previous data of tumor-related factors known to be associated with pCR; however, the current analysis found neither DM nor metformin to be independently associated with pCR. Thus, additional prospective study is warranted prior to validating metformin as an antitumor agent.

The impact of bariatric surgery on qualitative and quantitative breast density.

BACKGROUND: Obesity and breast density are associated with breast cancer in postmenopausal women. Bariatric surgery effectively treats morbid obesity, with sustainable weight loss and reductions in cancer incidence. We evaluated changes in qualitative and quantitative density; hypothesizing breast density would increase following bariatric surgery. METHODS: Women undergoing bariatric surgery from 1990 to 2015 were identified, excluding patients without a mammogram performed both before and after surgery. Changes in body mass index (BMI), time between mammograms and surgery, and American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) scores were assessed. VolparaDensity™ automated software calculated volumetric breast density (VBD), fibroglandular volume (FGV), and total breast volume for the 82 women with digital data available. Differences between pre- and postsurgery values were assessed. RESULTS: One hundred eighty women were included. Median age at surgery was 50.0 years, with 8.8 months between presurgery mammogram and surgery and 62.3 months between surgery and postsurgery mammogram. Median BMI significantly decreased over the study period (46.0 vs 35.4 kg/m2 ; P < 0.001). No change in BI-RADS scores was seen between the pre- and postsurgery mammograms. Eighty-two women had VolparaDensity™ data available. While VBD increased in these patients, FGV and total breast volume both decreased following bariatric surgery. CONCLUSIONS: Increased VBD, decreased FGV, and decreased total breast volume were seen following bariatric surgery-induced weight loss. There was no difference in qualitative breast density, highlighting the discrepancy between BI-RADS and VolparaDensity™ measurements. Further investigation will be required to determine how differential changes in components of breast density may affect breast cancer risk.

Sustained activation of the HER1-ERK1/2-RSK signaling pathway controls myoepithelial cell fate in human mammary tissue.

Human mammary glands arise from multipotent progenitor cells, which likely respond both to cell-autonomous and to extrinsic cues. However, the identity of these cues and how they might act remain unclear. We analyzed HER1 ligand effects on mammary morphogenesis using a three-dimensional organoid model generated from human breast tissue that recapitulates both qualitatively and quantitatively the normal ductal network in situ. Strikingly, different HER1 ligands generate distinct patterns of cell fate. Epidermal growth factor (EGF) causes a massive expansion of the myoepithelial lineage. Amphiregulin, in contrast, enables normal ductal development. These differences cannot be ascribed to preferential apoptosis or proliferation of differentiated cell populations, but are dependent on HER1 signal intensity. Inhibition of the extracellular signal-regulated kinase 1/2 (ERK1/2) effector RSK prevents the EGF-induced myoepithelial expansion. Notably, mouse mammary organoids are much less responsive to HER1 ligands. Little is known about the myoepithelial lineage or about growth factor effects on mammary progenitor differentiation, and our studies provide an important window into human mammary development that reveals unexpected differences from the mouse model.

The Changing Paradigms for Breast Cancer Surgery: Performing Fewer and Less-Invasive Operations.

Historically, through the conduct of prospective clinical trials, breast cancer surgeons have performed less radical breast and axillary surgeries with no survival decrement to our patients. Currently, other opportunities exist for the treating breast surgeon to do less. Possibilities include active surveillance for ductal carcinoma in situ, ablative therapy for small primary breast cancers, selective omission of a sentinel node biopsy, and selective elimination of breast surgery after neoadjuvant systemic therapy. Breast surgeons must be leaders in the development and testing of effective therapy with the least intervention possible.

Techniques for intraoperative radiation therapy for early-stage breast carcinoma.

Intraoperative radiation therapy (IORT) is a method of accelerated partial breast irradiation developed to replace other longer courses of radiotherapy with a single radiation session administered at the time of breast-conserving surgery. The purpose of this review is to summarize the advantages and disadvantages of breast IORT techniques that are currently available, as well to consider potential alternative techniques for breast IORT or ultra-short course breast radiotherapy. Furthermore, we highlight the published outcomes for the IORT treatment approaches including: electron therapy, superficial photon therapy and other techniques. Potential future directions of IORT are explored including novel IORT techniques utilizing intraoperative brachytherapy with in-room imaging and rapid treatment planning.

Use of prophylactic postoperative antibiotics during surgical drain presence following mastectomy.

BACKGROUND: National guidelines recommend one dose of perioperative antibiotics for breast surgery and discourage postoperative continuation. However, reported skin and soft tissue infection (SSI) rates after mastectomy range from 1-26 %, higher than expected for clean cases. Utility of routine or selective postoperative antibiotic use for duration of drain presence following mastectomy remains uncertain. METHODS: This study included all female patients who underwent mastectomy without reconstruction at our institution between 2005 and 2012. SSI was defined using CDC criteria or clinical diagnosis of cellulitis. Information on risk factors for infection (age, body mass index [BMI], smoking status, diabetes, steroid use), prior breast cancer treatment, drain duration, and antibiotic use was abstracted from medical records. Multivariable logistic regression was used to assess the association between postoperative antibiotic use and the occurrence of SSI, adjusting for concurrent risk factors. RESULTS: Among 480 patients undergoing mastectomy without reconstruction, 425 had sufficient documentation for analysis. Of these, 268 were prescribed antibiotics (63 %) at hospital discharge. An overall SSI rate of 7.3 % was observed, with 14 % of patients without postoperative antibiotics developing SSI compared with 3.4 % with antibiotics (p < 0.0001). Factors independently associated with SSI were smoking and advancing age. Diabetes, steroid use, BMI, prior breast surgery, neoadjuvant chemotherapy, prior radiation, concomitant axillary surgery, and drain duration were not associated with increased SSI rates. CONCLUSIONS: SSI rates among patients who did and did not receive postoperative antibiotics after mastectomy were significantly different, particularly among smokers and women of advanced age. These patient subgroups may warrant special consideration for postoperative antibiotics.

Novel Form of Breast Intraoperative Radiation Therapy with CT-Guided High-Dose-Rate Brachytherapy: Interim Results of a Prospective Phase-II Clinical Trial.

BACKGROUND: Precision breast intraoperative radiation therapy (PB-IORT) is a novel method of IORT that uses customized CT-based treatment plans and high-dose-rate (HDR) brachytherapy. We conducted a phase-II multi-institution trial to evaluate the efficacy of PB-IORT. STUDY DESIGN: Between 2015 and 2022, 3 centers enrolled women aged 45 years and older with invasive or in situ carcinoma measuring 3 cm or smaller and N0 status (n = 358). Breast-conserving surgery was performed, and a multilumen balloon catheter was placed in the lumpectomy bed. CT images were used to create customized HDR brachytherapy plans that delivered 12.5 Gy to the tumor bed. The primary outcome assessed was the 5-year rate of index quadrant tumor recurrence. An interim analysis was conducted after one-third of eligible participants completed 5 years of follow-up. This trial is registered with clinicaltrials.gov (NCT02400658). RESULTS: The cohort comprised 153 participants with a median age of 64 years and median follow-up time of 5.9 years. The estimated 5-year index quadrant tumor recurrence rate and overall survival were 5.08% (95% CI 2.23 to 9.68) and 95.1%, respectively. Locoregional (ipsilateral breast and axilla) and distant recurrence rates were each 1.96%. Seven deaths occurred during the first 5 years of follow-up, with only 1 attributable to breast cancer. Overall, 68.6% of patients experienced any adverse effects, and 4 cases of breast-related severe toxicities were observed. CONCLUSIONS: This study presents the results of a planned interim analysis of a phase-II trial investigating PB-IORT and demonstrates the efficacy and safety of single-fraction, CT-based, HDR brachytherapy after breast-conserving surgery. These findings provide valuable insights into the use of PB-IORT as a treatment modality.

MRI utilization in newly diagnosed breast cancer: a survey of practicing surgeons.

BACKGROUND: Whereas guidelines supporting breast MRI in high-risk screening exist, guidelines for MRI use in newly diagnosed breast cancer are lacking. We, therefore, conducted a study of breast surgeons to determine practice beliefs surrounding MRI use in newly diagnosed breast cancer. METHODS: A survey sent to 2,274 American Society of Breast Surgeons members in December 2010 queried routine MRI use (defined as >75 % of time) in specific clinical scenarios. Analyses were performed by respondent practice setting, practice volume, and practice specialization. Descriptive statistics and subgroup analysis using a χ(2) and logistic regression were used. RESULTS: Responses from 1,012 surgeons (45.5 % response rate) were eligible for analysis. Respondents represented diverse practice settings (20 % academic, 72 % private practice) and volume (≤50 new breast cancer patients, 36 %; 51-100, 26 %; 101-200, 25 %; >200, 13 %). Also, 41 % of surgeons indicated routine MRI use for newly diagnosed patients, with higher rates of use among surgeons from high-volume practices, high specialization, and private practice. Greater consensus in routine MRI use was seen in the setting of extreme mammographic density (87.9 %), strong family history of breast cancer (73.4 %), and invasive lobular carcinoma (69.4 %). Responses were increasingly discordant in setting of pursuing breast conservation (47.4 %), invasive ductal carcinoma (41.8 %), and ductal carcinoma in situ (37.2 %). Personal experience was the most commonly cited influence on MRI use. CONCLUSIONS: Divergent responses in MRI use in newly diagnosed breast cancer reflect clinical uncertainty and variable practice beliefs among breast surgeons. Such diverging practice patterns highlight areas where clinical research and guidelines may be most helpful.

A theory-based decision aid for patients with cancer: results of feasibility and acceptability testing of DecisionKEYS for cancer.

PURPOSE: Appropriate utilization of treatment is a goal for all patients undergoing cancer treatment. Proper treatment maximizes benefit and limits exposure to unnecessary measures. This report describes findings of the feasibility and acceptability of implementing a short, clinic-based decision aid and presents an in-depth clinical profile of the participants. METHODS: This descriptive study used a prospective, quantitative approach to obtain the feasibility and acceptability of a decision aid (DecisionKEYS for Balancing Choices) for use in clinical settings. It combined results of trials of patients with three different common malignancies. All groups used the same decision aid series. Participants included 80 patients with solid tumors (22 with newly diagnosed breast cancer, 19 with advanced prostate cancer, and 39 with advanced lung cancer) and their 80 supporters as well as their physicians and nurses, for a total of 160 participants and 10 health professionals. RESULTS: The decision aid was highly acceptable to patient and supporter participants in all diagnostic groups. It was feasible for use in clinic settings; the overall value was rated highly. Of six physicians, all found the interactive format with the help of the nurse as feasible and acceptable. Nurses also rated the decision aid favorably. CONCLUSIONS: This intervention provides the opportunity to enhance decision making about cancer treatment and warrants further study including larger and more diverse groups. Strengths of the study included a theoretical grounding, feasibility testing of a practical clinic-based intervention, and summative evaluation of acceptability of the intervention by patient and supporter pairs. Further research also is needed to test the effectiveness of the decision aid in diverse clinical settings and to determine if this intervention can decrease overall costs.

Identifying the effectiveness of 3D culture systems to recapitulate breast tumor tissue in situ.

PURPOSE: Breast cancer heterogeneity contributes to chemotherapy resistance and decreased patient survival. To improve patient outcomes it is essential to develop a technology that is able to rapidly select the most efficacious therapy that targets the diverse phenotypes present within the tumor. Breast cancer organoid technologies are proposed as an attractive approach for evaluating drug responses prior to patient therapy. However, there remain challenges in evaluating the effectiveness of organoid cultures to recapitulate the heterogeneity present in the patient tumor in situ. METHOD: Organoids were generated from seven normal breast and nineteen breast cancer tissues diagnosed as estrogen receptor positive or triple negative. The Jensen-Shannon divergence index, a measure of the similarity between distributions, was used to compare and evaluate heterogeneity in starting tissue and their resultant organoids. Heterogeneity was analyzed using cytokeratin 8 and cytokeratin 14, which provided an easily scored readout. RESULTS: In the in vitro culture system HER1 and FGFR were able to drive intra-tumor heterogeneity to generate divergent phenotypes that have different sensitivities to chemotherapies. CONCLUSION: Our methodology, which focuses on quantifiable cellular phenotypes, provides a tractable system that complements omics approaches to provide an unprecedented view of heterogeneity and will enhance the identification of novel therapies and facilitate personalized medicine.

Focused ultrasound ablation for the treatment of breast cancer.

Advances in technology and changes in our understanding of tumor biology have allowed breast cancer treatment to evolve toward less disfiguring procedures. Noninvasive ablative therapy is a natural continuation of this trend. The following paper presents the concepts underpinning focused ultrasound ablation therapy for the treatment of breast cancer and reviews the investigative experience to date in the evaluation of this promising technique.

An evaluation of a computer-imaging program to prepare women for chemotherapy-related alopecia.

OBJECTIVE: This study was conducted to evaluate a computer program named Help with Adjustment to Alopecia by Image Recovery (HAAIR) that was developed to provide educational support and reduce distress in women with hair loss following chemotherapy. METHODS: Forty-five women who had been diagnosed with cancer and anticipated alopecia following treatment were randomly assigned to either the Imagining group (IG) or Standardized Care group (SCG). Patients in the IG used a computer-imaging program that created the patient's image on a screen to simulate baldness and use of wigs whereas patients in the SCG were directed to a resource room at the Cancer Center established for women with chemotherapy-related alopecia. Assessment data using the Brief Symptom Inventory, Importance of Hair Questionnaire, and the Brief Cope were completed at baseline (T1), before chemotherapy and hair loss, following hair loss (T2), and 3 months follow-up (T3). RESULTS: All women were able to successfully use the touch screen computerized-imaging program and reported that using the computer was a positive, helpful experience, thus establishing acceptability and usability. Women in both the IG and the SCG group showed significantly lower hair loss distress scores at T2 after hair loss than at T1 with T3 distress scores increasing in the SCG and decreasing in the IG. Those with avoidance coping reported more distress. CONCLUSIONS: This evaluation demonstrates that the HAAIR program is a patient-endorsed educational and supportive complement to care for women facing chemotherapy-related alopecia.

Toxicity and cosmetic outcomes after treatment with a novel form of breast IORT.

PURPOSE: Intraoperative radiation therapy (IORT), a form of accelerated partial breast irradiation (APBI), is an appealing alternative to postoperative whole breast irradiation for early-stage breast cancer. The purpose of this study was to examine the toxicity and cosmetic outcomes of patients treated with a novel form of breast IORT (precision breast IORT; PB-IORT), that delivers a targeted, higher dose of radiation than conventional IORT. METHODS AND MATERIALS: The first 204 patients treated with PB-IORT in a Phase II clinical trial (NCT02400658) with 12 months of followup were included. Trial inclusion criteria were age ≥45 years, invasive or in situ breast cancer, tumor size ≤3 cm, and node negative. Toxicity and cosmetic scoring were performed at 6 and 12 months. RESULTS: 98 patients (48%; 95% CI, 41-55%) experienced toxicity. Seven Grade 3 toxicities occurred (3.4%; 95% CI, 1.4-6.9%). Most patients (95%) had excellent or good cosmetic outcomes (95% CI, 91-98%) at 12 months. Most patients (94%) had little or no pigmentation change (95% CI, 90-97%), 88% little to no size change (95% CI, 82-92%), and 87% experienced minimal shape change (95% CI, 82-92%). CONCLUSIONS: Overall, Grade 3+ toxicity was rare and cosmetic outcomes were excellent. Severe toxicity with PB-IORT is similar to that reported in the TARGIT trial (3.3% rate of major toxicity) but lower than APBI (NSABP-39, 10.1% Grade 3/4 toxicities). We propose that the toxicity of PB-IORT compared with TARGIT and NSABP-39 is related to the radiation dose and delivery schedule. PB-IORT offers low-toxicity and good cosmetic outcomes when compared with other forms of APBI.

Treatment of Breast Fibroadenoma with Ultrasound-Guided High-Intensity Focused Ultrasound Ablation: A Feasibility Study.

OBJECTIVE: Breast fibroadenomas (FAs) are common, benign, and often bothersome. Current management includes observation or surgical excision. This study evaluated the safety and feasibility of ultrasound-guided high-intensity focused ultrasound ablation for the treatment of FAs. METHODS: Twenty women with a palpable, biopsy-confirmed FA were enrolled in a prospective trial, and they underwent treatment utilizing an ultrasound-guided high-intensity focused ultrasound ablation device. Tumors were greater than 1 cm in diameter, with volumes of 0.3-10 cc. Safety, treatment experience, toxicity, cosmesis, and change in tumor size on palpation and ultrasound measurement were obtained before and after treatment at 3, 6, and 12 months. RESULTS: All of the 20 patients completed therapy. Pretreatment mean tumor volume was 1.8 cc (standard deviation = 1.23, range 0.57-5.7). Half of the patients reported a painful mass before treatment. All adverse events were well tolerated and transient, with the most common being mild pain, reported by 15 of 20 patients during treatment, and 14 of 20 at the day-7 postprocedure follow-up. Mean pain score during treatment was 16, and at day 7, it was 12.2, on a scale from 0 to 100 (100 = worst pain). Mean patient satisfaction was 4.4 on a scale of 1-5 (5 = most satisfied). Mean likelihood of recommending treatment was 4.7 (5 = most likely). At the 12-month postprocedure follow-up, the mean reduction in volume of the FA was 65.5% on ultrasound; the mass was no longer palpable in 80% of the patients; no patients reported pain; and cosmesis was rated as excellent in all patients. CONCLUSION: Ultrasound-guided high-intensity focused ultrasound ablation appears to be effective, safe, and well tolerated for the treatment of FAs. A larger multicenter clinical trial is currently under way.

Use of Mental Health Apps by Breast Cancer Patients and Their Caregivers in the United States: Protocol for a Pilot Pre-Post Study.

BACKGROUND: Over one-third of cancer patients experience clinically significant mental distress, and distress in caregivers can exceed that of the cancer patients for whom they care. There is an urgent need to identify scalable and cost-efficient ways of delivering mental health interventions to cancer patients and their loved ones. OBJECTIVE: The aim of this study is to describe the protocol to pilot a mobile app-based mental health intervention in breast cancer patients and caregivers. METHODS: The IntelliCare mental health apps are grounded in evidence-based research in psychology. They have not been examined in cancer populations. This pilot study will adopt a within-subject, pre-post study design to inform a potential phase III randomized controlled trial. A target sample of 50 individuals (with roughly equal numbers of patients and caregivers) at least 18 years of age and fluent in English will be recruited at a US National Cancer Institute designated clinical cancer center. Consent will be obtained in writing and a mobile phone will be provided if needed. Self-report surveys assessing mental health outcomes will be administered at a baseline session and after a 7-week intervention. Before using the apps, participants will receive a 30-min coaching call to explain their purpose and function. A 10-min coaching call 3 weeks later will check on user progress and address questions or barriers to use. Self-report and semistructured interviews with participants at the end of the study period will focus on user experience and suggestions for improving the apps and coaching in future studies. RESULTS: This study is ongoing, and recruitment will be completed by the end of 2018. CONCLUSIONS: Results from this study will inform how scalable mobile phone-delivered programs can be used to support breast cancer patients and their loved ones. TRIAL REGISTRATION: ClinicalTrials.gov NCT03488745; https://clinicaltrials.gov/ct2/show/NCT03488745. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/11452.

Implementation of an HDR brachytherapy-based breast IORT program: Initial experiences.

PURPOSE: A multidisciplinary team at our institution developed a novel method of intraoperative breast radiation therapy (precision breast intraoperative radiation therapy [PB-IORT]) that uses high-dose-rate brachytherapy with CT on-rails imaging to deliver high-dose, customized radiotherapy to patients with early-stage breast cancer. This report summarizes our program's experience developing and implementing PB-IORT. METHODS AND MATERIALS: Literature on PB-IORT was reviewed including published articles and abstracts. To evaluate case volume, all patients with a breast cancer diagnosis who underwent breast surgery or breast radiation (2010-2017) at our academic institution were identified. Patients were stratified into pre-IORT and post-IORT eras with initiation of our PB-IORT program in October 2013. Overall trends in surgical and radiation therapy volume in each era were analyzed by linear regression. Travel distance for all surgical patients was calculated using Google Maps (Alphabet Inc.) and then compared between IORT and non-IORT patients. RESULTS: Data from a PB-IORT Phase 1 trial found that the primary endpoints were met and that PB-IORT is feasible and safe. The direct health system's delivery costs for PB-IORT exceed those of 16-fraction whole-breast irradiation when accounting for consumable supplies (multilumen balloon applicator = $2,750 per patient). There was a significant increase in yearly growth of breast cancer surgical volume with PB-IORT. CONCLUSIONS: Accrual rates for the ongoing Phase II trial have been quicker than expected in an area where more research is needed. The rapid accrual indicates patient interest and demand for this treatment and that it is very feasible to get more data from randomized trials.

ERα-Mediated Nuclear Sequestration of RSK2 Is Required for ER+ Breast Cancer Tumorigenesis.

Although ribosomal protein S6 kinase A3 (RSK2) activation status positively correlates with patient responses to antiestrogen hormonal therapies, the mechanistic basis for these observations is unknown. Using multiple in vitro and in vivo models of estrogen receptor-positive (ER+) breast cancer, we report that ERα sequesters active RSK2 into the nucleus to promote neoplastic transformation and facilitate metastatic tumor growth. RSK2 physically interacted with ERα through its N terminus to activate a proneoplastic transcriptional network critical to the ER+ lineage in the mammary gland, thereby providing a gene signature that effectively stratified patient tumors according to ERα status. ER+ tumor growth was strongly dependent on nuclear RSK2, and transgenic mice engineered to stably express nuclear RSK2 in the mammary gland developed high-grade ductal carcinoma in situ Mammary cells isolated from the transgenic model and introduced systemically successfully disseminated and established metastatic lesions. Antiestrogens disrupted the interaction between RSK2 and ERα, driving RSK2 into the cytoplasm and impairing tumor formation. These findings establish RSK2 as an obligate participant of ERα-mediated transcriptional programs, tumorigenesis, and divergent patient responses to antiestrogen therapies.Significance: Nuclear accumulation of active RSK drives a protumorigenic transcriptional program and renders ER+ breast cancer susceptible to endocrine-based therapies. Cancer Res; 78(8); 2014-25. ©2018 AACR.

Utility of CT imaging in a novel form of high-dose-rate intraoperative breast radiation therapy.

INTRODUCTION: Intraoperative radiation therapy (IORT) is an alternative to whole breast radiation following breast conserving surgery. Conventional breast IORT is limited by lack of cross-sectional imaging. In response, our institution developed Precision Breast IORT (PB-IORT) which utilizes intraoperative computed tomography (CT) images for confirmation of brachytherapy applicator placement and for treatment planning. The purpose of this study was to determine the utility of CT imaging in PB-IORT in the first 103 patients treated in two prospective clinical trials. METHODS: We retrospectively reviewed the first 103 patients treated with PB-IORT. All patients underwent breast surgery and placement of a multi-lumen brachytherapy applicator. Patients had a CT scan followed by high-dose-rate (HDR) brachytherapy. Endpoints were the number of patients having more than one CT during PB-IORT and the number of treatment plans having image-based modifications. RESULTS: After initial CT scan, 27 patients (26.2%) had findings prompting surgical applicator adjustment. One patient underwent an additional scan to localize a biopsy clip and aid in excision to negative margin. Eighty-one patients (78.6%) had dosimetry modifications based on CT findings with 36 plans (35.0%) adjusted to protect the skin or chest wall and 45 plans (43.7%) to protect both the skin and chest wall. CONCLUSIONS: Computed tomography findings prompted treatment alterations in the majority of patients treated with PB-IORT to enhance tissue conformity and to sculpt the radiation dose away from normal tissues. CT imaging is unique to PB-IORT. These findings suggest the potential clinical superiority of PB-IORT given its allowance for patient-specific alterations.