Chromatin profile-based identification of a novel ER-positive breast cancer subgroup with reduced ER-responsive element accessibility.

BACKGROUND: Oestrogen receptor (ER) signalling-dependent cancer cell growth is one of the major features of ER-positive breast cancer (BC). Inhibition of ER function is a standard and effective treatment for ER-positive tumours; however, ~20% of patients with ER-positive BC experience early or late recurrence. In this study, we examined intertumour heterogeneity from an epigenetic perspective based on the hypothesis that the intrinsic difference in epigenetic states around ER signalling pathway underlies endocrine therapy resistance. METHODS: We performed transposase-accessible chromatin sequencing (ATAC-seq) analysis of 42 BC samples, including 35 ER-positive(+) human epidermal growth factor receptor 2 (HER2)-negative(-) and 7 triple-negative tumours. We also reanalysed ATAC-seq data of 45 ER + /HER2 - tumours in the Cancer Genome Atlas (TCGA) BC cohort to validate our observations. RESULTS: We conducted a comprehensive analysis of cis-regulatory elements (CREs) using ATAC-seq, identifying three subgroups based on chromatin accessibility profiles. We identified a subgroup of ER-positive BCs with a distinctive chromatin accessibility pattern including reduced accessibility to ER-responsive elements (EREs). The same subgroup was also observed in TCGA BC cohort. Despite the reduced accessibility to EREs, the expression of ER and potential ER target genes were not decreased in these tumours. CONCLUSION: Our findings highlight the existence of a subset of ER-positive BCs with unchanged ER expression but reduced EREs accessibility that cannot be distinguished by conventional immunostaining for ER. Future studies should determine whether these tumours are associated with resistance to endocrine therapy.

Clinical significance of the neutrophil-to-lymphocyte ratio in oligometastatic breast cancer.

PURPOSE: This study investigated the clinical impact of pretreatment neutrophil-to-lymphocyte ratio (NLR) on survival in patients with oligometastatic breast cancer. PATIENTS AND METHODS: We collected data from 397 patients who underwent primary breast surgery from 2004 to 2015 and developed recurrence during the follow-up. We reviewed the images and clinical information and defined OMD according to the European Society for Medical Oncology advanced breast cancer guidelines. The NLR was calculated using pretreatment data of primary breast cancer. The cutoff value of the NLR was determined by receiver operating characteristic curve with Youden Index. RESULTS: Among 397 patients, 131 had OMD at recurrence. The low-NLR group included patients of significantly older age at primary cancer than those in the high-NLR group. A low NLR indicated a better overall survival (p = 0.023) after adjusting for relevant factors, including estrogen receptor status, surgical resection of metastatic disease, metastatic organ number, disease-free interval, and liver metastasis than did the high-NLR group. We developed prognostic models for OMD using six independent prognostic factors, including the NLR. The number of factors was associated with overall survival; patients with all six favorable factors showed a good overall survival of 90.9% at 8 years and those with four or more factors showed 70.4%. CONCLUSIONS: The NLR was an independent prognostic factor for overall survival in OMD. The number of favorable prognostic factors was associated with overall survival. A prognostic model, including the NLR, will help identify patients with a favorable prognosis.

Trastuzumab and fulvestrant combination therapy for women with advanced breast cancer positive for hormone receptor and human epidermal growth factor receptor 2: a retrospective single-center study.

BACKGROUND: Trastuzumab and fulvestrant combination therapy is one of the treatment options for patients with hormone receptor- and human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer; however, there are limited studies evaluating the efficacy of this combination therapy. METHODS: We retrospectively reviewed the data of women with hormone receptor- and HER2-positive metastatic breast cancer who received trastuzumab and fulvestrant combination therapy between August 1997 and August 2020 at the Cancer Institute Hospital. The primary endpoint of this study was progression-free survival, and the secondary endpoints were response rate, overall survival and safety. RESULTS: We reviewed the data of 1612 patients with recurrent or metastatic breast cancer, of which 118 patients were diagnosed with hormone receptor- and HER2-positive breast cancer. Of these, 28 patients who received trastuzumab and fulvestrant combination therapy were eligible for this study. The median treatment line for advanced breast cancer was 6 (range, 1-14), the median progression-free survival was 6.4 months (95% confidence interval [CI], 3.46-8.17), and the median overall survival was 35.3 months (95% CI, 20.0-46.7). Of the 28 patients, partial response was observed in 1 (4%), stable disease in 17 (61%), and progressive disease in 10 (36%) patients. The disease control rate was 64%. Adverse events of grade ≥ 3 were not observed. CONCLUSIONS: Trastuzumab and fulvestrant combination therapy showed moderate clinical efficacy and no severe toxicity after standard anti-HER2 treatment, which is a reasonable treatment option for patients with hormone receptor- and HER2-positive metastatic breast cancer. These data contribute to understanding the efficacy of trastuzumab and fulvestrant combination therapy as control data for further development of anti-HER2 agents plus hormone therapy.

Clinical benefit of treatment after trastuzumab emtansine for HER2-positive metastatic breast cancer: a real-world multi-centre cohort study in Japan (WJOG12519B).

BACKGROUND: Trastuzumab emtansine (T-DM1) treatment for human epidermal growth factor receptor-2 (HER2)-positive metastatic breast cancer after taxane with trastuzumab and pertuzumab is standard therapy. However, treatment strategies beyond T-DM1 are still in development with insufficient evidence of their effectiveness. Here, we aimed to evaluate real-world treatment choice and efficacy of treatments after T-DM1 for HER2-positive metastatic breast cancer. METHODS: In this multi-centre retrospective cohort study involving 17 hospitals, 325 female HER2-positive metastatic breast cancer patients whose post-T-DM1 treatment began between April 15, 2014 and December 31, 2018 were enrolled. The primary end point was the objective response rate (ORR) of post-T-DM1 treatments. Secondary end points included disease control rate (DCR), progression-free survival (PFS), time to treatment failure (TTF), and overall survival (OS). RESULTS: The median number of prior treatments of post-T-DM1 treatment was four. The types of post-T-DM1 treatments included (1) chemotherapy in combination with trastuzumab and pertuzumab (n = 102; 31.4%), (2) chemotherapy concomitant with trastuzumab (n = 78; 24.0%), (3), lapatinib with capecitabine (n = 63; 19.4%), and (4) others (n = 82; 25.2%). ORR was 22.8% [95% confidence interval (CI): 18.1-28.0], DCR = 66.6% (95% CI 60.8-72.0), median PFS = 6.1 months (95% CI 5.3-6.7), median TTF = 5.1 months (95% CI 4.4-5.6), and median OS = 23.7 months (95% CI 20.7-27.4). CONCLUSION: The benefits of treatments after T-DM1 are limited. Further investigation of new treatment strategies beyond T-DM1 is awaited for HER2-positive metastatic breast cancer patients.

Lenvatinib induces early tumor shrinkage in patients with advanced thyroid carcinoma.

Although advanced thyroid carcinoma patients who cannot be cured by conventional therapy have lacked effective treatment, multitargeted tyrosine kinase inhibitors have recently become available. Phase 3 trials of lenvatinib showed a median time to objective response of 2 (95 % confidence interval (CI) 1.9-3.5) months, demonstrating that shrinks tumors rapidly. The phenomenon of immediate tumor shrink is known as early tumor shrinkage (ETS) which is related to clinical outcome in other malignancies. However, precisely when within 8 weeks lenvatinib starts to affect tumors remains unclear. In tumors near the carotid arteries, trachea, or esophagus, a rapid therapeutic effect can induce fistula formation or arterial bleeding. To prevent such treatment-emergent serious adverse events (SAE), early imaging evaluation seems to be very important. In this study, the point in time when lenvatinib started to shrink tumors was retrospectively investigated. The subjects were 16 patients who started lenvatinib administration between May and August 2015. Tumor size was evaluated by computed tomography (CT) scans frequently within the first 8 weeks according to the Response Evaluation Criteria In Solid Tumors (RECIST) guideline. Initial tumor response was defined as ≥ 10% tumor reduction. Serum thyroglobulin (Tg) level was monitored in 8 differentiated thyroid carcinoma (DTC) without TgAb patients. At the first evaluation, 13 patients (83.3 %) showed tumor reduction and that decreased with time. Thirteen patients (83.3 %) showed >10 % tumor reduction within 8 weeks. In all DTC patients, serum Tg level was markedly decreased. In conclusion, lenvatinib immediately shrinks tumors, the so-called ETS phenomenon. Therefore, careful attention should be paid to fistula formation from the early phase.

Immunohistochemical co-expression status of cytokeratin 5/6, androgen receptor, and p53 as prognostic factors of adjuvant chemotherapy for triple negative breast cancer.

Triple negative breast cancer (TNBC) is immunohistochemically characterised by the lack of expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor type 2 (HER2). TNBC is known for its poor prognosis and high recurrence probability. There is no effective targeted treatment for TNBC, but only adjuvant chemotherapies. There are two TNBC subtypes, basal-like and non-basal-like, which are defined based on positive cytokeratin (CK) 5/6 and/or epidermal growth factor receptor (EGFR) expression. In particular, CK5/6 expression is reported to correlate with TNBC recurrence. TNBC lacks ER-α expression, but some TNBCs are known to express the androgen receptor (AR). Moreover, although p53 accumulation is detected in various malignant tumors, its influence on adjuvant chemotherapy for patients with TNBC remains unclear. The aim of this study was to assess the combined immunohistochemical expression of CK 5/6, AR, and p53 as a potential prognostic marker of adjuvant chemotherapy for patients with TNBC. The expression of CK5/6, AR, and p53 in formalin-fixed and paraffin-embedded (FFPE) surgical sections from 52 patients with TNBC was analysed by immunohistochemistry (IHC) and the co-expression patterns in individual cells were investigated by immunofluorescent (IF) staining. Low AR expression was correlated with high clinical stage (P < 0.05) and low nuclear grade (P < 0.05). The expression of CK5/6 and p53 did not correlate with clinicopathological features. Patients who needed adjuvant chemotherapy presented the worst prognosis. In particular, when the IHC expression pattern was CK5/6 (-), AR (-), and p53 (+), the disease free survival (DFS) and overall survival (OS) were the worst. On the other hand, patients with AR (+) and p53 (-) TNBC presented a good prognosis. The analysis of the co-expression status of these three markers showed that no cells presented both AR and CK5/6 expression. Furthermore, TP53 mRNA expression was higher in patients with AR-negative TNBC (P < 0.05) and in patients with the worst prognosis (P < 0.05) than in the other patients. These results suggested that, in patients with CK5/6-negative TNBC, AR expression correlated with good prognosis, but p53 accumulation correlated with poor prognosis. The present IHC markers allowed us to predict the post-surgery prognosis of patients with TNBC. In conclusion, TNBCs are heterogeneous. Patients with the CK5/6 (-), AR (-), and p53 (+) TNBC subtype, evaluated by IHC, presented the worst prognosis. These IHC markers will be helpful to follow patients with TNBC.

Altered intracellular region of MUC1 and disrupted correlation of polarity-related molecules in breast cancer subtypes.

MUC1 glycoprotein is overexpressed and its intracellular localization altered during breast carcinoma tumorigenesis. The present study aimed to clarify the relationship of cytoplasmic localization of MUC1 with the breast cancer subtype and the correlation of 10 molecules associated with cell polarity in breast cancer subtypes. We immunostained 131 formalin-fixed and paraffin-embedded breast cancer specimens with an anti-MUC1 antibody (MUC1/CORE). For 48 of the 131 tumor specimens, laser-assisted microdissection and real-time quantitative RT-PCR were performed to analyze mRNA levels of MUC1 and 10 molecules, ß-catenin, E-cadherin, claudin 3, claudin 4, claudin 7, RhoA, cdc42, Rac1, Par3 and Par6. Localization of MUC1 protein varied among breast cancer subtypes, that is, both the apical domain and cytoplasm in luminal A-like tumors (P < 0.01) and both the cytoplasm and cell membrane in luminal B-like (growth factor receptor 2 [HER2]+) tumors (P < 0.05), and no expression was found in triple negative tumors (P < 0.001). Estrogen receptor (ER)+ breast cancers showed higher MUC1 mRNA levels than ER- breast cancers (P < 0.01). The incidence of mutual correlations of expression levels between two of the 10 molecules (55 combinations) was 54.5% in normal breast tissue and 38.2% in luminal A-like specimens, 16.4% in luminal B-like (HER2+), 3.6% in HER2 and 18.2% in triple negative specimens. In conclusion, each breast cancer subtype has characteristic cytoplasmic localization patterns of MUC1 and different degrees of disrupted correlation of the expression levels between the 10 examined molecules in comparison with normal breast tissue.

[CD147 expression in non-invasive and invasive breast carcinoma].

CD147 is a multifunctional membrane glycoprotein involved in tumor invasion, and is overexpressed in many solid tumors. However, the role of CD147 in breast cancer is not well understood. The aim of this study was to evaluate CD147 expression in non-invasive and invasive ductal carcinomas. We recruited 156 breast cancer patients who underwent radical operations at our hospital up until 2002. We performed immunohistochemistry on their tumor specimens, and compared these data with clinicopathological factors. We divided the patients into two groups: group A was comprised of non-invasive ductal carcinomas and group B, invasive ductal carcinomas. The CD147-positive rate was 62.8% for all patients and was higher in group B than group A. In all cases, the CD147-positive rate correlated with clinical stage, number of metastatic lymph nodes, and tumor size. These results implied that CD147 may be involved in the process of breast cancer invasion.

[Indoleamine 2,3-dioxygenase activity during toremifene therapy for aromatase inhibitor-resistant metastatic breast cancer].

We evaluated the clinical significance of indoleamine 2,3-dioxygenase(IDO)activity during toremifene(TOR)therapy for aromatase inhibitor(AI) / -resistant metastatic breast cancer. IDO activity can be measured using the tryptophan/kynurenine (Trp/Kyn)ratio. Trp and Kyn were measured using high performance liquid chromatography(HPLC). The response rate of TOR therapy for AI-resistant metastatic breast cancer patients was 21.9%, and the clinical benefit rate was 62.5%. The serum Trp/Kyn ratio was significantly lower in AI-resistant metastatic breast cancer patients with distant metastases than in patients who had local recurrence. During TOR therapy, IDO activity was significantly decreased in the TOR responder group compared to the TOR non-responder group. IDO activity correlated with the number of metastatic lesions treated during TOR therapy. These results suggest that the Trp/Kyn ratio is a useful measurement in evaluating the immunological metastatic status during endocrine therapy.

[Indoleamine 2,3-dioxygenase activity in breast cancer patients with local recurrence or distant metastases].

We evaluated the significance of indoleamine 2,3-dioxygenase(IDO)activity in breast cancer patients with local recurrence or distant metastases. IDO activity can be determined using the tryptophan/kynurenine(Trp/Kyn)ratio. Trp and Kyn were measured by high-performance liquid chromatography(HPLC). The survival rate after recurrence was higher in the local recurrence group(n=11)than in the distant metastases group(n=26). The mean Trp/Kyn ratio was lower in the distant metastases group than in the local recurrence group. The mean Trp/Kyn ratio was also lower in patients who had multiple metastases than in patients who had a single metastatic lesion. The Trp/Kyn ratio decreased during chemotherapy in all patients who received chemotherapy.

[Success rate of breast conserving surgery for different breast cancer screening methods].

We evaluated the significance of the success rate of breast conserving surgery in patients with breast cancer discovered by using different screening methods. Patients underwent either population-based screening (group A) or opportunistic screening(group B). We retrospectively investigated patients who visited our hospital in 2012. A total of 552 patients visited our hospital for breast cancer screening. Thirty-five percent of these patients were diagnosed with breast cancer based on the histopathological results. The rate of breast cancer discovery was significantly higher in group B than in group A. The rate of discovery of early clinical stage breast cancer was also higher in group B than in group A. The rate of total breast conserving surgery for breast cancer screening cases was 54.4%. The rate of breast conserving surgery was higher in group B than in group A. Group A patients only underwent mammography, while 80.1% of group B patients underwent mammography plus ultrasonography. These results suggest that adding ultrasonography to breast cancer screening is useful for detection of early breast cancer.

[Usefulness of reductive surgery for elderly advanced breast cancer with bone metastases - a case report].

We report the case of an elderly, advanced breast cancer patient with multiple bone metastases. Breast reduction surgery was useful for this patient. The patient was an 81-year-old woman who had a breast lump. A core needle biopsy for breast cancer led to a diagnosis of invasive ductal carcinoma. The mucinous carcinoma was estrogen receptor (ER) nd progesterone receptor (PgR) positive and HER2/neu negative. Due to patient complications, it was not possible to treat with chemotherapy. The patient was administrated aromatase inhibitors (AI) and zoledronic acid hydrate. However, the AI treatment was not effective, and so she was administered toremifene. Toremifene treatment was effective for 6 months, after which she received fulvestrant. Fulvestrant treatment maintained stable disease (SD)for 14 months. After 14 months of fulvestrant treatment, serum concentrations of the tumor markers CA15-3, CEA, and BCA225 increased. We therefore decided to perform surgical breast reduction surgery. The pathological diagnosis from the surgically resected specimen was mucinous carcinoma, positive for ER and HER2, and negative for PgR. After surgery, serum concentrations of the tumor markers decreased. Following surgery, the patient was administrated lapatinib plus denosumab plus fulvestrant. The patient remains well, without bone metastases, 2 years and 6 months after surgery.

[A case of anaplastic thyroid carcinoma with surgical treatment].

We describe a case of a 52-year-old man who presented with a neck tumor. Ultrasonography and a neck computed tomography (CT) scan revealed a large, 6-cm mass in the left thyroid lobe. Analysis of cytological specimens obtained from the mass indicated the tumor was classIV (indicative of anaplastic carcinoma). In addition, chest CT revealed multiple small nodules in the lung, which we suspected were metastases from the primary thyroid carcinoma. To relieve pressure symptoms in the neck, we performed left hemithyroidectomy and lymph node dissection. Six months after surgery, a chest CT scan revealed enlargement of a nodule in the left lung. CT-guided biopsy of the left lung mass indicated a histopathological diagnosis of metastasis from anaplastic carcinoma. Four cycles of paclitaxel chemotherapy suppressed enlargement of the lung tumor. The patient's general condition gradually deteriorated; however, and he died 15 months after surgery. Anaplastic carcinoma of the thyroid is generally considered to be one of the most aggressive cancers encountered in humans. In this case, surgical intervention led to improved clinical symptoms and prognosis.

[Indoleamine 2, 3-dioxygenase activity during neoadjuvant chemotherapy in patients with breast cancer].

We evaluated the significance of indoleamine 2, 3-dioxygenase (IDO) in breast cancer patients during neoadjuvant chemotherapy. IDO activity can be determined by the tryptophan( Trp)/kynurenine( Kyn) ratio. Trp and Kyn were measured by high performance liquid chromatography (HPLC). The correlations between the Trp/Kyn ratios in the pre-chemotherapy, post-chemotherapy, and post-surgery phases of treatment and the effects of chemotherapy were studied. The Trp/ Kyn ratios were significantly lower in the post-epirubicin and cyclophosphamide( EC) chemotherapy phase and post- weekly paclitaxel( wPac) chemotherapy phase than in the pre-chemotherapy phase and post-chemotherapy phase, respectively. There was no significant correlation between the Trp/Kyn ratio in any phase and the response rate. These results suggest that measurement of the Trp/Kyn ratio is not useful for predicting the rate of response to chemotherapy in patients with breast cancer.

[Indoleamine 2, 3-dioxygenase activity for breast cancer patients with recurrence 5 or more years after surgery].

We evaluated the significance of indoleamine 2, 3-dioxygenase( IDO) in breast cancer patients with recurrence 5 or more years after surgery. IDO activity can be measured by the tryptophan (Trp)/kynurenine (Kyn) ratio. Trp and Kyn were measured by high-performance liquid chromatography( HPLC). We encountered 32 patients in whom breast cancer recurred 5 or more years after surgery. The mean age of the patients was 56.8 years. The mean duration of years since the initial treatment for breast cancer was 9.3±3.8 years. The rate of hormone receptor positivity was 93.8%. Twelve patients were suitable for locoregional therapy and the remaining 20 patients required chemotherapy. The patients suitable for locoregional therapy had a better prognosis than those who required chemotherapy. The correlation of the Trp/Kyn ratio between these 2 groups (locoregional therapy group and chemotherapy group) was studied. The Trp/Kyn ratio was higher in patients suitable for locoregional therapy than in those who received chemotherapy. The prognosis was better in patients with a high Trp/Kyn ratio than in those with a low Trp/Kyn ratio. These results suggest that determining the Trp/Kyn ratio was useful in the prognosis of patients with breast cancer that recurred 5 or more years after surgery.

[Diagnosis of ductal carcinoma in situ with interruption of the anterior border of the mammary gland by ultrasonography-a case report].

We report a case of ductal carcinoma in situ( DCIS) with interruption of the anterior border of the mammary gland by ultrasonography. The patient was a 41-year-old woman. The patient was identified by a focal asymmetric density on her left breast by screening mammography. Ultrasonography showed an ill-defined low echoic mass, 25 mm in diameter, in the A area of her left breast. The tumor had features consistent with the interruption of the anterior border of the mammary gland. Therefore, she was diagnosed with invasive ductal carcinoma of the breast. We performed a modified radical mastectomy with sentinel lymph node biopsy. A resected specimen led to a diagnosis of DCIS positive for estrogen receptor and progesterone receptor, and negative for HER2/neu protein expression. After surgery, she was administered tamoxifen. One year and 6 months after the operation, she is well without metastases. Ultrasonography is generally useful to differentiate between a DCIS lesion or an invasive ductal carcinoma lesion. However, in this case, we could not diagnose the tumor as DCIS by ultrasonography because the tumor was interrupted by the anterior border of the mammary gland. This case suggests that we should be cautious when diagnosing low echoic tumors with interruption of the anterior border of the mammary gland by ultrasonography.

[Successful treatment of neuroendocrine ductal carcinoma in situ with loco-regional therapy].

Herein, we report the use of microdochectomy for neuroendocrine ductal carcinoma in situ( NE-DCIS). The patient was 44-year-old woman who experienced spontaneous nipple discharge for 5 years. We were unable to detect the origin of the nipple discharge by computed tomography (CT), magnetic resonance imaging (MRI), mammography, ductal endoscopy, or ultrasonography. Subsequently, endoscopy-assisted microdochectomy was performed under local anesthesia. Pathological examination of the resected specimen led to a diagnosis of NE-DCIS positive for estrogen and progesterone receptors and negative for HER2/neu protein expression. The Ki-67 positive cell index was 80%. The surgical margins were negative. After surgery, tamoxifen was administered. One year after the operation, the patient is well and metastases have not been noted. This case suggests that endoscopy-assisted microdochectomy under local anesthesia is useful for evaluating spontaneous nipple discharge.

[Long-term response to eribulin in patients with metastatic breast cancer-report of 2 cases].

Case 1: Case 1 involved a 42-year-old woman who had been diagnosed as having advanced breast cancer (Stage III B). She had previously received 6 courses of cyclophosphamide, epirubicin, and 5-fluorouracil CEF, 14 courses of weekly paclitaxel, and 2 courses of vinorelbine( VNR). After the courses of chemotherapy, she underwent modified radical mastectomy with axillary lymph node dissection. Two years after surgery, lung metastases were found, and the patient received 6 courses of weekly paclitaxel and 13 courses of nab-paclitaxel. However, the lung metastases progressed after the courses of chemotherapy, and therefore, we decided to administer eribulin as third-line chemotherapy. Eribulin was effective against the lung metastases for more than 1 year. Case 2: Case 2 involved a 52-year-old woman who had been diagnosed as having Stage IIB breast cancer. She had received 4 courses of CEF and 4 courses of docetaxel as neo-adjuvant chemotherapy. After chemotherapy, she underwent breast-conserving surgery with axillary lymph node dissection. Five years postoperatively, multiple liver metastases were found, and the patient received 3 courses. However, the liver metastases progressed after this chemotherapy. Subsequently, we administered nab-paclitaxel; however, it produced severe side effects. We then decided to administer eribulin as second-line chemotherapy. Eribulin was effective against the liver metastases for more than 1 year.

[Analysis of indoleamine 2, 3-dioxygenase expression in breast cancer patients with bone metastasis].

We evaluated the clinical significance of indoleamine 2, 3-dioxygenase (IDO) expression in breast cancer patients with bone metastasis. IDO activity can be measured by the tryptophan(Trp)/kynurenine(Kyn) ratio. Trp and Kyn levels were measured by high-performance liquid chromatography (HPLC). The serum IDO levels of postoperative breast cancer patients with a high number of bone metastases were lower than those of patients with a single metastasis lesion. In addition, IDO activity increased in the cases in which the number of metastatic lesions to the bone increased. These results suggest that the expression of IDO in breast cancer patients with bone metastasis may play a critical role in immunosuppression in these patients.