Published papers

Objective: This study aimed to compare the efficacy and safety of the newest bipolar vessel sealing system (BVSS; LigaSure™ Small Jaw) to that of conventional technique in axillary dissection. Methods: Sixty-one patients with breast cancer were randomized to a conventional dissection surgical technique (CONV group; n = 30) by scalpel and monopolar cautery or that using a vessel sealing system (BVSS group; n = 31). Results: There was a significant difference between both groups in the mean number of days until drain removal (6.4 ± 2.9 vs. 8.2 ± 3.8 days; P value = 0.033), and the mean total volume of drainage fluid (365.3 ± 242.2 vs. 625.1 ± 446.6 mL; P value = 0.009). The incidence of seroma was similar in both groups (43.3 vs. 37.9 %; P value = 0.673). There was no statistically significant difference in axillary dissection operating time (66 vs. 70 min; P value = 0.371), or the mean volume of blood loss (18.2 ± 31.1 vs. 20.6 ± 26.3 mL; P value = 0.663). Conclusions: Our results suggest that BVSS is a more effective device when compared to the conventional techniques in axillary dissection.

Biological markers for breast cancer are biomolecules that result from cancer-related processes and are associated with particular clinical outcomes; they thus help predict responses to therapy. In recent years, gene expression profiling has made themolecular classification of breast cancer possible. Classification of breast cancer by immunohistochemical expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 and Ki-67 is standard practice for clinical decision- making. Assessments of hormone receptor expression and human epidermal growth factor receptor 2 overexpression help estimate benefits from targeted therapies and have greatly improved prognoses for women with these breast cancer types. Although Ki-67 positivity is associated with an adverse outcome, its clear identification is an aid to optimal disease management. Standardization of testingmethodology to minimize inter-laboratory measurement variations is a remaining issue.Multigene assays provide prognostic information and identify those most likely to benefit from systemic chemotherapy. Incorporating molecular profiles with conventional pathological classification would bemore precise, and could enhance the clinical development of personalized therapy in breast cancer.

INTRODCUTION Although nipple sparing mastectomy (NSM) has attracted increased recognition as an alternative to traditional mastectomy approaches, its oncological safety is unclear. The purpose of this study was to compare the local recurrence rate between NSM and total mastectomy (TM). METHODS: Between 2003 and 2013, 121 and 557 patients with stage 0-III breast cancer underwent NSM and TM respectively. Multivariate Cox regression and propensity score models were used to compare the two groups. RESULTS: There was no significant difference in the five-year local recurrence rate between the NSM and TM groups (7.6% vs 4.9%, p=0.398). In multivariate analysis, NSM was not a risk factor for local recurrence (hazard ratio: 1.653, 95% confidence interval: 0.586-4.663, p=0.343). Propensity score matching found similar five-year local recurrence free survival rates between the two groups (92.3% vs 93.7%, p=0.655). CONCLUSIONS: Our results suggest that NSM may provide oncological safety comparable with mastectomy for carefully selected patients.

Introduction: The role of sentinel lymph node biopsy (SLNB) in patients with ipsilateral breast tumor recurrence (IBTR) remains to be elucidated. The aim of this study was to evaluate feasibility and validity of SLNB in patients with IBTR. Methods: A prospective database of 1172 patients with clinically node-negative breast cancer who underwent SLNB from January 2005 to December 2013 at Keio University Hospital was analyzed and 35 patients with IBTR underwent SLNB. Sentinel lymph nodes (SLNs) were detected using a combined method of blue dye and radioisotope or indocyanine green fluorescence in cases with failure of identification by blue dye and radioisotope. Results: Twenty-two patients had previous SLNB, eight had previous axillary lymph node dissection (ALND), and five had no previous axillary surgery. Overall, SLNs were successfully identified in 28 (80.0%) of 35 patients. The identification rate in patients with previous SLNB, ALND and no axillary surgery was 81.8% (18/22), 75% (6/8) and 80% (4/5), respectively (P = 0.52). Aberrant drainage outside the ipsilateral axilla was found more frequently in patients with previous ALND compared with SLNB and no axillary treatment (37.5% vs. 4.5% vs. 0%, P = 0.048). No axillary recurrence was observed after median follow-up of 40.3 months from the second surgery for IBTR. Conclusions: SLNB is a technically feasible and valid procedure for staging and treatment of regional lymph nodes in patients with IBTR.

This paper introduces a registration and projection method for directly projecting the tumor region for breast cancer surgery assistance based on the breast procedure of our collaborating doctor. We investigated the steps of the breast cancer procedure of our collaborating doctor and how it can be applied for tumor region projection. We propose a novel way of MRI acquisition so we may correlate the MRI coordinates to the patient in the real world. By calculating the transformation matrix from the MRI coordinates and the coordinates from the markers that is on the patient, we are able to register the acquired MRI data to the patient. Our registration and presentation method of the tumor region was then evaluated by medical doctors.

In this paper we propose an augmented reality system that superimposes MRI onto the patient model. We use a half-silvered mirror and a handheld device to superimpose the MRI onto the patient model. By tracking the coordinates of the patient model and the handheld device using optical markers, we are able to transform the images to the correlated position. Voxel data of the MRI are made so that the user is able to view the MRI from many different angles.

B-cell translocation gene 2 (BTG2), a gene suppressed in a subset of aggressive breast cancer, is repressed by estrogen. BTG2 inhibits the expression of HER ligands and promotes AKT activation, which plays an essential role in the tamoxifen resistance of estrogen receptor (ER)-positive breast cancer. To determine if BTG2 expression modifies tamoxifen efficacy, a cohort of 60 patients treated with adjuvant tamoxifen monotherapy was analyzed. We found that increased BTG2 expression showed better clinical survival and was the only independent prognostic factor for disease-free survival (hazard ratio, 0.691; 95% confidence interval, 0.495-0.963; P = 0.029). Tamoxifen suppressed the human epidermal growth factor receptor 2 (HER2)-Akt signaling in BTG2 expressing ER-positive breast cancer cells with a correlated increase in sensitivity, whereas BTG2 knockdown abrogated this sensitivity. Consistent with this observation, tamoxifen significantly suppressed the growth ratio, tumor weight and Ki-67 expression in BTG2 expressing breast cancer xenografts in mice. These studies demonstrate that BTG2 is a significant factor in tamoxifen response, acting through modification of AKT activation in ER-positive/HER2-negative breast cancer. Tamoxifen treatment effectively inhibits tumor progression with BTG2 expression in mouse xenograft experiment.

Homeobox B9 (HOXB9), a member of the homeobox gene family, is overexpressed in breast cancer and promotes tumor progression and metastasis by stimulating epithelial-to-mesenchymal transition and angiogenesis within the tumor microenvironment. HOXB9 activates the TGFβ-ATM axis, leading to checkpoint activation and DNA repair, which engenders radioresistance in breast cancer cells. Despite detailed reports of the role of HOXB9 in breast cancer, the factors that regulate HOXB9 transcription have not been extensively examined. Here we uncover an underlying mechanism that may suggest novel targeting strategies for breast cancer treatment. To identify a transcription factor binding site (TFBS) in the HOXB9 promoter region, a dual luciferase reporter assay was conducted. Protein candidates that may directly attach to a TFBS of HOXB9 were examined by Q-PCR, electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), and mutation analysis. A HOXB9 promoter region from -404 to -392 was identified as TFBS, and E2F1 was a potential binding candidate in this region. The induction of HOXB9 expression by E2F1 was observed by Q-PCR in several breast cancer cell lines overexpressing E2F1. The stimulatory effect of E2F1 on HOXB9 transcription and its ability to bind the TFBS were confirmed by luciferase, EMSA and ChIP assay. Immunohistochemical analysis of 139 breast cancer tissue samples revealed a significant correlation between E2F1 and HOXB9 expression (p<0.001). Furthermore, a CDK4/6 inhibitor suppressed E2F1 expression and also reduced expression of HOXB9 and its downstream target genes. Our in vitro analysis identified the TFBS of the HOXB9 promoter region and suggested that E2F1 is a direct regulator of HOXB9 expression; these data support the strong correlation we found between E2F1 and HOXB9 in clinical breast cancer samples. These results suggest that targeting the E2F1/HOXB9 axis may be a novel strategy for the control or prevention of cancer progression and metastasis.

The growing number of antihuman epidermal growth factor receptor-2 (HER2) agents suggests the need for defining the optimal choice of neoadjuvant therapy for HER2-positive breast cancer. This study aims to assess the efficacy and safety of neoadjuvant therapy for HER2-positive breast cancer. Randomized trials that compared different anti-HER2 regimens in the neoadjuvant setting were included. The odds ratio (OR) for pathological complete response (pCR), treatment completion, and safety was utilized for pooling effect sizes. Network meta-analysis using a Bayesian statistical model was performed to combine the direct and indirect evidence of neoadjuvant therapy for HER2-positive breast cancer. All statistical tests were two-sided. A database search identified 1047 articles, with 10 studies meeting the eligibility criteria. A total of 2247 patients in seven different treatment arms were assessed. Anti-HER2 agents evaluated included trastuzumab (tzmb), lapatinib (lpnb), and pertuzumab (pzmb). Network meta-analysis showed no statistically significant difference between dual targeting treatment arms; however, lpnb reduced treatment completion due to adverse events. Patients in dual targeting arms had statistically significantly more pCR than those in other treatment arms (chemotherapy [CT] + tzmb + pzmb vs CT + tzmb, OR = 2.29, 95% credibility interval = 1.02 to 5.02, P = .02). The surface under the cumulative ranking probability curve indicated that CT + tzmb + pzmb had the highest probability of being the best treatment arm in terms of pCR. This study indicates that combining two anti-HER2 agents with CT is the most effective treatment modality in the neoadjuvant setting for HER2-positive breast cancer.

Background: Discordance rates of hormone receptor (HR) and human epidermal growth factor-2 (HER2) status between primary and recurrent breast cancer were reported to be in the wide range of 10–40 %, although its prognostic relevance remains to be elucidated.Methods: Fifty-five breast cancer patients had biopsies or resections of recurrent lesions. Pathological assessments of the HR and HER2 status of primary and recurrent lesions were performed in a single laboratory at Keio University Hospital. Tumors were classified as luminal (HR+ and HER2−), luminal/HER2 (HR+ and HER2+), HER2 (HR− and HER2+), or triple negative (HR− and HER2−).Results: Discordance rates in estrogen receptor (ER), progesterone receptor (PgR) and HER2 status between primary tumors and recurrent lesions were 16.4, 30.9 and 10.2 %, respectively. Overall, 14 patients (25.5 %) changed subtypes at recurrent lesions. Patients with a gain in ER and PgR status had a significantly longer disease-free interval compared with the corresponding concordant-negative patients (ER: 99.0 vs. 18.5 months, p = 0.037, PgR: 141.0 vs. 24.4 months, p = 0.011). Patients with a loss of HER2 status experienced a trend toward shorter time to progression, compared with patients who maintained HER2 positivity (4.0 vs. 18.4 months, p = 0.051).Conclusions: Discordance in receptor status between primary and recurrent breast cancers were seen in 10–30 %. A gain in HR status was significantly associated with better prognosis.

Background: Breast cancer is a heterogeneous disease with a diversity of clinical behaviors. The purpose of this study was to evaluate the utility of breast cancer intrinsic subtypes in the prediction of pathological complete response (pCR) in a cohort of breast cancer patients receiving preoperative chemotherapy. Methods: Patients with stage II/III breast cancer received 4 cycles of XT (capecitabine and docetaxel) followed by 4 cycles of FEC (fluorouracil, epirubicin, and cyclophosphamide) as preoperative chemotherapy. Tumors were classified as luminal A, luminal B, luminal/HER2, HER2, basal-like, or non-basal-like triple negative by immunohistochemical analysis in core needle biopsy samples at baseline. Results: The overall pCR rate was 11.9% (12/101). Multivariate analysis showed that intrinsic subtype was an independent factor to predict pCR. With luminal A patients as the reference group, luminal B (OR = 16.39; 95% CI 1.44-185.88; p = 0.024), HER2 (OR = 14.73; 95% CI 1.19-180.84; p = 0.035), and basal-like (OR = 13.27; 95% CI 1.27-138.79; p = 0.031) patients had a significantly higher likelihood of pCR. Conclusion: The present data indicate that intrinsic subtypes may be useful predictive biomarkers of pCR in breast cancer patients treated with preoperative chemotherapy.

Background Neoadjuvant chemotherapy (NAC) is the standard treatment for locally advanced breast cancer. It is now being used to treat operable breast cancer to facilitate breast-conserving surgery, but the accuracy of sentinel lymph node biopsy (SLNB) in breast cancer patients receiving NAC remains open to considerable debate. Methods We enrolled 96 patients with stage II-III breast cancer who received NAC from January 2001 to July 2010. All patients underwent breast surgery and SLNB, followed immediately by complete axillary lymph node dissection (ALND). Sentinel lymph nodes were detected with blue dye and radiocolloid injected intradermally just above the tumor and then evaluated with hematoxylin and eosin and immunohistochemical staining. Results The overall identification rate for SLNB was 87.5 % (84/96); the false negative rate (FNR) was 24.5 % (12/49); and the accuracy rate was 85.7 % (72/84). The FNR was significantly lower in clinically node-negative patients than in node-positive patients before NAC (5.5 % vs. 35.5 %; p = 0.001). Accuracy was also significantly higher in clinically node-negative patients than in nodepositive patients before NAC (97.2 % vs. 77.1 %; p = 0.009). The FNR was 27.3 % among 46 clinically nodepositive patients before NAC who were clinically nodenegative after NAC. Among 12 patients with a complete tumor response (CR), the FNR was 0 %, compared with 26.1 % for 83 patients with a partial response and stable disease (p = 0.404). Conclusions Although associated with a high FNR after NAC, SLNB would have successfully replaced ALND in clinically node-negative patients before NAC and in patients with a CR after NAC.

Background. Studies have suggested that HOXB9 expression in breast cancer cells promotes cellular invasiveness, metastatic ability, and tumor neovascularization in the surrounding tissue in in vitro and in vivo assays. These findings imply that HOXB9 overexpression may alter tumor-specific cell fates and the tumor stromal microenvironment, contributing to breast cancer progression. The objective of this study was to analyze whether these results could be applied to clinical practice. Methods. A total of 141 consecutive, invasive ductal carcinoma patients who underwent surgical treatment were examined. Immunohistochemical staining was performed to evaluate the expression of HOXB9, Ki-67, CD31, and CD34, and the association of tumor proliferation and angiogenesis with HOXB9 expression was analyzed. Results. Of the 141 tumor specimens immunostained for HOXB9, 69 (48.9%) stained positive. Larger primary tumor size, hormone receptor negativity, HER2 positivity, higher nuclear grade, and number of pathologic nodal metastases were significant variables associated with HOXB9 expression. Notably, 12 (92.3%) of 13 triple-negative breast cancer cases showed HOXB9 expression. Disease-free survival and overall survival were significantly different between the HOXB9-positive and HOXB9-negative groups (hazard ratio 20.714, P = 0.001; and hazard ratio 9.206, P = 0.003, respectively). Multivariate analysis indicated that HOXB9 expression was the only independent prognostic factor for disease-free survival (hazard ratio 15.532, P = 0.009). HOXB9-positive tumors showed a significant increase in the number of vasculature and the Ki-67 ratio compared with HOXB9-negative tumors. Conclusions. HOXB9 expression, which promotes tumor proliferation and angiogenesis, is a significant prognostic factor in breast cancer.

Primary systemic chemotherapy has become a standard of care for operable breast cancer patients who are candidates for adjuvant chemotherapy. Induction of pathological complete response (pCR) is one of the main goals of primary systemic chemotherapy because patients with pCR have shown a better prognosis. The definition of pCR has varied across clinical trials. It would be ideal for all researchers to use the same terminology in describing pathologic response. Identification of accurate predictive factors of pCR to primary systemic chemotherapy is urgent, because patients with a low chance of pCR and clinical response should be spared unnecessary toxicity. Early response to primary systemic chemotherapy might be correlated with a high probability of a pCR. Therefore, evaluation of early response is useful to avoid unnecessary toxicity without potential benefit from chemotherapy.

Background: The prognostic significance of sentinel lymph node (SLN) micrometastases and the need for axillary lymph node dissection (ALND) on patients with micrometastases in SLNs remain controversial. Methods: A prospective database of 657 breast cancer patients who underwent SLN biopsy (SLNB) was analyzed. SLNs were detected using a combined method of isosulfan blue dye and small-sized technetium-99m-labeled tin colloid. Results: Micrometastases in SLNs were found in 50 (7.6%) of 657 patients. Twenty-nine (58.0%) of 50 patients with micrometastatic SLNs underwent ALND and no further metastases were found in non-sentinel lymph nodes. Among 21 patients (42.0%) with micrometastatic SLNs who decided to forego ALND, no axillary lymph node recurrence has been observed during a median follow-up time of 47 months. There is no significant difference in recurrence-free survival between the patients with micrometastatic and negative SLNs (p = 0.90). Conclusions: These data suggest that it may not be necessary to perform ALND on patients with micrometastases in SLNs and that the presence of micrometastases in SLNs may not be associated with prognosis.