Risk factors of unintentional piecemeal resection in endoscopic mucosal resection for colorectal polyps ≥ 10 mm.

This study aimed to investigate the lesion and endoscopist factors associated with unintentional endoscopic piecemeal mucosal resection (uniEPMR) of colorectal lesions ≥ 10 mm. uniEPMR was defined from the medical record as anything other than a preoperatively planned EPMR. Factors leading to uniEPMR were identified by retrospective univariate and multivariate analyses of lesions ≥ 10 mm (adenoma including sessile serrated lesion and carcinoma) that were treated with endoscopic mucosal resection (EMR) at three hospitals. Additionally, a questionnaire survey was conducted to determine the number of cases treated by each endoscopist. A learning curve (LC) was created for each lesion size based on the number of experienced cases and the percentage of uniEPMR. Of 2557 lesions, 327 lesions underwent uniEPMR. The recurrence rate of uniEPMR was 2.8%. Multivariate analysis showed that lesion diameter ≥ 30 mm (odds ratio 11.83, 95% confidence interval 6.80-20.60, p < 0.0001) was the most associated risk factor leading to uniEPMR. In the LC analysis, the proportion of uniEPMR decreased for lesion sizes of 10-19 mm until 160 cases. The proportion of uniEPMR decreased with the number of experienced cases in the 20-29 mm range, while there was no correlation between the number of experienced cases and the proportion of uniEPMR ≥ 30 mm. These results suggest that 160 cases seem to be the minimum number of cases needed to be proficient in en bloc EMR. Additionally, while lesion sizes of 10-29 mm are considered suitable for EMR, lesion sizes ≥ 30 mm are not applicable for en bloc EMR from the perspective of both lesion and endoscopist factors.

Can endoscopic sphincterotomy be performed safely in elderly patients aged 80 years or older with pancreatic and biliary diseases?

BACKGROUND/AIMS: The purpose of this study was to investigate whether endoscopic sphincterotomy (EST) can be usefully and safely performed in elderly patients aged 80 years or older. METHODOLOGY: The eligible patients with pancreatic and biliary diseases who required EST were divided into two groups depending on their age: under 80 (group A) and 80 or older (group B). Patient characteristics, EST success rate and incidence of the related complications were evaluated. RESULTS: Of the 720 patients who required EST, 522 patients were in group A and 198 in group B. Group B incidences of patient characteristics at baseline disease and anticoagulant/antiplatelet therapy were significantly higher than in group A (p<0.05). The EST success rates were 97.1% (507/522) in group A and 96.5% (191/198) in group B. The incidences of the related complications were 8.8% (46/522) in group A and 4% (8/198) in group B, respectively, again without significant difference. CONCLUSIONS: The EST success rate and the incidence of related complications were comparable between patients in groups A and B, indicating that EST can be safely performed even in the elderly aged 80 years or older.

Long-term outcome of the WallFlex partially covered stent for unresectable malignant biliary obstruction: a multicenter single-arm prospective study.

BACKGROUND/AIMS: Covered metallic stent was developed to prevent tumor ingrowth. However, procedural accidents due to its insertion often occur and migration after long-term insertion causes problems. The WallFlex partially covered stent (WF) with reduced axial force enables stenting along the bile duct. We examined the usefulness of WF placement in an unresectable malignant distal biliary obstruction. METHODOLOGY: We examined procedural accidents, stent obstruction rate, and patency period caused by WF insertion. RESULTS: Ninety-seven patients were analyzed; procedural accidents caused by WF insertion occurred in 8 patients (7.2%) composed of acute cholecystitis in 3 patients (3.2%), acute pancreatitis in 2 patients (2.1%), acute cholangitis in 1 patient (1%), and other in 1 patient (1%). The stent obstruction rate was 19.6% (19 patients), and obstruction cause includes sludge in 9 patients (9.3%), migration in 4 patients (4.1%), food impaction in 3 patients (3.1%), ingrowth in 1 patient (1%), overgrowth in 0 patients (0%), and unknown in 2 patients (2.1%). The mean stent patency period was 634.918 +/- 66.545 (7-946) days. CONCLUSIONS: WF has less procedural accidents when inserted into unresectable malignant biliary obstruction patients with reduced migration rate after a long period and low obstruction rate.

Comparison of the accuracy of breast cytological diagnosis at seven institutions in southern Fukuoka Prefecture, Japan.

OBJECTIVE: Cytological examination is inexpensive and relatively simple to carry out and deserves utilization in breast cancer screening. We investigated the status of cytological diagnosis at seven facilities in southern Fukuoka Prefecture, Japan. METHODS: We collected data on the criteria for cytological judgments and status of breast cytological diagnosis at seven different facilities in this region. RESULTS: Among 5693 individuals who underwent breast cytological examination, analyses were conducted on 1250 individuals (22.0%) in whom cytological diagnoses were confirmed by histological diagnoses. Among these patients, cytological diagnosis had an absolute sensitivity of 71.9%, a specificity of 76.0%, a false-negative value of 6.7% and a false-positive value of 0.08%. At three facilities with relatively large numbers of cases (>300), excluding a facility for specialized breast disease, similar trends of high complete sensitivity (94.3, 95.6 and 97.1%, respectively) and low absolute sensitivity (60.4, 74.8 and 57.2%, respectively) were found. No false-negative or false-positive cases were seen in individual facilities with relatively low numbers of cases (<150). CONCLUSIONS: The accuracy of cytological diagnosis at the facilities we surveyed was relatively high compared with the goals of assessment of diagnostic accuracy. However, the performance was dependent on the facility type, i.e. number of cases, staff involved and whether it was specialized or not, making the diagnosis specific for this region. We recommend that management of the accuracy of cytological diagnosis be undertaken jointly by multiple facilities to establish systems in Japan that lead to more useful diagnostic tools.

FDG-PET/CT in the diagnosis of recurrent breast cancer.

BACKGROUND: An advantage of PET/CT has been demonstrated for diagnosis of several tumor entities. In patients with breast cancer, early diagnosis and accurate restaging of recurrence after surgery is important for selection of the most appropriate therapeutic strategy. Purpose To evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) using 18F-fluorodeoxyglucose (FDG), for follow-up of patients with suspected recurrent breast cancer. MATERIAL AND METHODS: Forty-seven patients with suspected recurrent breast cancer underwent PET/CT. The PET and PET/CT images were interpreted without knowledge of the results of other diagnostic modalities, and compared with each other with reference to the final diagnosis. RESULTS: Twenty-five (53%) patients suffered tumor recurrence. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 96%, 91%, 92%, 95%, and 94%, respectively. In comparison with PET, PET/CT had a higher sensitivity and accuracy (96% vs. 80% and 94% vs. 81%, respectively). The difference in diagnostic accuracy between PET/CT and PET was significant (P < 0.05). CONCLUSION: The present findings indicate that PET/CT is an accurate, sensitive and reliable modality for screening and detection of breast cancer recurrence. PET/CT appears to be an effective surveillance tool, as it is able to cover the whole body in a single procedure and shows good performance.

Immunohistochemical study of metaplastic carcinoma and central acellular carcinoma of the breast: central acellular carcinoma is related to metaplastic carcinoma.

Metaplastic breast cancers (MBCs) [spindle cell carcinoma (SpCC), squamous cell carcinoma (SCC), and matrix-producing carcinoma (MPC)] and invasive carcinomas with central acellular zones (CACs) were analyzed with respect to biological potential by immunohistochemical analyses. Specimens from 40 patients [20 with MBCs (7 with SCC, 6 with SpCC, 5 with MPC, and 2 with mixed type)] and 20 with CACs were analyzed using antibodies to cytokeratin (CK) 8, 5/6, 14, AE1/AE3, 34αE12, involucrin, c-kit, vimentin (VIM), alpha-smooth muscle actin, p63, epidermal growth factor receptor, epithelial cell adhesion molecule, and estrogen receptor (ER)/progesterone receptor (PR)/HER2. Expression of CK5/6, 34ßE12, VIM, nuclear p63, and cytoplasmic p63 was significantly higher with MBCs than CACs (38%/13%, 70%/43%, 85%/33%, 68%/40%, and 48%/18%, respectively). Other markers were expressed at various levels in these tumors, but the difference between them was not significant. Eighteen MBC and 8 CAC cases were triple (ER/PR/HER2) negative; 17 MBCs and 7 CACs were basal-like tumors. Several differences were seen in MBCs and CACs, but they were heterogeneous, differentiating multipotentially into mesenchymal, myoepithelial, basal-like phenotypes with "stem cell-like" features. Thus, CACs are related to MBCs by immunohistochemical analyses as well as according to morphological findings.

[Two cases of adult T-Cell leukemia/lymphoma with main lesion in stomach treated by VCAP-AMP-VECP regimen].

We report two cases of adult T-cell leukemia/lymphoma(ATLL)having their main lesions in the stomach. Case 1 was a 74-year-old man, complaining of left upper abdominal mass and pain. Upper gastrointestinal endoscopy revealed an ulcerous lesion in the stomach. Histological analysis and southern blotting for HTLV-1 pro-viral DNA led us to our diagnosis of ATLL. There were no apparent lesions in the bone marrow and other organs. He died of tumor lysis and multi-organ failure shortly after treatment with the VCAP-AMP-VECP regimen. Case 2 was a 68-year-old man complaining of abdominal bloating and pain. Upper gastrointestinal endoscopy disclosed an irregularity of the gastric mucosa. A biopsy sample was diagnosed pathohistologically as non-Hodgkin's lymphoma. We conducted total gastrectomy. Based on the results from the histological study and southern blotting for HTLV-1 p ro-viral DNA in the resected specimen, a diagnosis of ATLL was made. We treated him with a VCAP-AMP-VECP regimen, but multiple bone metastases and pathologic fracture occurred, proving that the disease was progressive. ATLL having a main lesion in the stomach is rare, and requires an accumulation of cases analyzed with careful diagnostic approach to establish a standard therapy for it.

Renal thrombotic microangiopathy associated with chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Thrombotic microangiopathy (TMA) is a major complication after hematopoietic stem cell transplantation (HSCT). In this study, we examined the clinical and pathologic features of 2 patients and 5 autopsy cases with HSCT-associated renal TMA to clarify the association between graft-versus-host disease (GVHD) and renal TMA. The median interval between HSCT and renal biopsy or autopsy was 7 months (range 3-42 months). Clinically, acute and chronic GVHD occurred in 7 and 4 patients, respectively. Clinical evidence for TMA was detected in 2 patients, while chronic kidney disease developed in all patients. The main histopathological findings were diffuse endothelial injury in glomeruli, peritubular capillaries (PTCs), and small arteries. In addition, all cases showed glomerulitis, renal tubulitis, and peritubular capillaritis with infiltration of CD3+ T cells and TIA-1+ cytotoxic cells, suggesting that GVHD occurred during the development of TMA. Diffuse and patchy C4d deposition was noted in glomerular capillaries and PTCs, respectively, in 2 biopsy and 2 autopsy cases, suggesting the involvement of antibody-mediated renal endothelial injury in more than 50% of renal TMA cases. In conclusion, the kidney is a potential target of chronic GVHD that may induce the development of HSCT-associated TMA. Importantly, some cases are associated with chronic humoral GVHD.

"High-grade" central acellular carcinoma and matrix-producing carcinoma of the breast: correlation between ultrasonographic findings and pathological features.

High-grade carcinoma with a large central acellular zone (central acellular carcinoma, CAC) and matrixproducing carcinoma (MPC) are aggressive tumors that both have a central myxomatous acellular zone. Their characteristic morphology may be useful in diagnostic imaging. Ultrasonographic findings based on the Breast Imaging Recording and Data System (BI-RADS) and detailed histological features were evaluated in 11 cases of CAC and 2 cases of MPC to characterize their features. Safranin-O staining was undertaken for the evaluation of central acellular zones in these tumors. Overall, ultrasonography demonstrated heterogeneous hyperechoic lesions in the center of the hypoechoic mass. Posterior echo enhancement was observed in all but 1 case. One case was classified as malignant and the others as "borderline." Histologically, cancer tissue was located in the periphery of the tumor with a ring-like structure and fewer cellular central areas comprising hyaline cartilage myxoid material such as those stained by safranin-O. The present study showed that the pathological findings of CACs and MPCs accurately reflect the ultrasonographic findings. Tumors that showed hyperechoic areas in the center of the hypoechoic mass, with posterior echo enhancement indicating acellular zones composed by myxochondroid material, and that were also relatively round on ultrasonography may be benign, but evaluation is required to exclude CAC and MPC.

Clinical utility of intraductal US to decrease early recurrence rate of common bile duct stones after endoscopic papillotomy.

BACKGROUND AND AIM: The aim of the present study was to determine whether additional intraductal ultrasound (IDUS) to confirm complete stone clearance decreases the recurrence rate of common bile duct stones for a 3-year period after endoscopic papillotomy (EPT). METHODS: IDUS was carried out with a thin-caliber ultrasonic probe (diameter 2.0 mm, frequency 20 MHz) via transpapillary route after stone extraction. If IDUS showed evidence of residual stones and/or sludge, endoscopic management was performed until IDUS examination was negative. A prospective study was conducted on 59 consecutive patients undergoing additional IDUS after stone extraction between January 1996 and May 2003 (IDUS group). The recurrence rate of common bile duct stones was compared with a historical control group (August 1988 to December 1995) consisting of cases that did not undergo IDUS (non-IDUS group). Potential risk factors for recurrence of common bile duct stones were assessed by univariate and multivariate analysis on logistic regression. RESULTS: In 14 of 59 patients (23.7%), IDUS detected small residual stones not seen on cholangiography. The recurrence rate was 13.2% (17 of 129 patients) in the non-IDUS group and 3.4% (two of 59 patients) in the IDUS group (P < 0.05). Multivariate analysis subsequently identified non-IDUS status as an independent risk factor for recurrence (odds ratio 5.12, 95% CI 1.11-23.52, P = 0.036). CONCLUSIONS: Additional IDUS to confirm complete stone clearance after EPT decreases the early recurrence rate of common bile duct stones.

Diagnostic value of magnetic resonance cholangiopancreatography for clinically suspicious spontaneous passage of bile duct stones.

BACKGROUND AND AIM: We investigated the usefulness of magnetic resonance cholangiopancreatography (MRCP) and the need for endoscopic retrograde cholangiopancreatography (ERCP) in patients with clinically suspicious spontaneous passage of bile duct stones. METHODS: The study population consisted of 113 patients suspected of having common duct bile stones. Of them, 50 patients were clinically suspected of spontaneous passage of bile duct stones based on the presence of gallbladder stones on ultrasound examination or a history of common bile duct stones after cholecystectomy, clinical symptoms including abdominal pain and fever associated with inflammatory reaction and marked rise of hepatobiliary enzymes which resolved or normalized after conservative treatment without evidence of stones in the common bile duct on MRCP. These 50 patients were prospectively followed up for a median of 10.2 months. RESULTS: All patients except for one had had no symptoms related to cholangitis. Only one patient received ERCP due to recurrence of symptoms after 6 months. CONCLUSION: When clinical symptoms improve, hematological parameters normalize, and MRCP indicates that there are no stones in the common bile duct, it can be considered that the stones have passed naturally.

Value of peroral cholangioscopy for mucin-producing bile duct tumor.

Mucin-producing bile duct tumor is a rare biliary tract tumor. Despite the development of modern diagnostic technologies such as ultrasonography, and angiography, the precise determination of this tumor is difficult because of ambiguity caused by the abundant mucin secreted by the tumor and/or by the superficial mucosal spread of the tumor along the bile duct. Given these problems, selective percutaneous transhepatic biliary drainage (PTBD) and percutaneous transhepatic cholangioscopy (PTCS) are indispensable for the accuracy staging of this cancer. But, PTCS has a risk of a rare but serous complications, seeding metastasis at the sinus tract of PTBD, whereas the retrograde approach minimizes this risk. We report the case of a patient who underwent the successful resection of a mucin-producing bile duct tumor. The tumor was diagnosed preoperatively as originating in the left caudate lobe after ERC and peroral cholangioscopy (POCS).

Magnetic resonance cholangiopancreatography: potential usefulness of dehydrocholic acid (DHCA) administration in the evaluation of biliary disease.

BACKGROUND/AIMS: The aim of this study was to investigate whether exogenous dehydrocholic acid (DHCA) was useful to enhance the delineation of the biliary tree. METHODOLOGY: Our study population comprised 14 patients. Magnetic resonance cholangiopancreatography was acquired before and after the administration of DHCA. Two different MRCP snap shot techniques were applied: thick-slab two-dimensional (2D) (coronal) single shot turbo spin echo T2-weighted sequences and multisection thin-slab, 2D (coronal) single shot turbo spin echo T2-weighted sequences with three-dimensional (3D) maximum intensity projection (MIP) post processing. Volume rendering was prepared based on the source images, and the pixel size was visually adjusted to the biliary area of MRCP to measure the biliary tree volume. RESULTS: DHCA increased the bile duct volume in 13 of the 14 patients. It provided a better visualization of the biliary tree in 11 patients. The three patients without improvement in visualization included 1 patient with liver cirrhosis secondary to portoenterostomy for congenital biliary dilatation and 2 patients with cholecystectomy who had the bile ducts filled with bile by the time of the administration. CONCLUSIONS: It was suggested that administration of DHCA could enhance the delineation of the biliary tree on MRCP images.

Magnetic resonance cholangiopancreatography: potential usefulness of dehydrocholic acid (DHCA) administration in the evaluation of anastomotic site.

BACKGROUND/AIMS: The aim of this study was to investigate whether exogenous dehydrocholic acid (DHCA) was useful to enhance the delineation of anastomotic site. METHODOLOGY: DHCA is a cholagogue which produces an immediate effect by acting directly on liver cells. Its choleretic effect is strong, appearing 1 to 3 minutes after intravenous injection, reaching the maximum level in 20 to 30 minutes. Our study population comprised 9 patients. Magnetic resonance cholangiopancreatography (MRCP) was acquired before and after the administration of DHCA. Two different MRCP snap-shot techniques were applied: thick-slab two-dimensional (2D) (coronal) single-shot turbo spin echo T2-weighted sequences and multisection thin-slab, 2D (coronal) single shot turbo spin echo T2-weighted sequences with three-dimensional (3D) maximum intensity projection (MIP) post processing. RESULTS: DHCA provided a better visualization of the anastomotic site in 7 patients (77.8%). The two patients without improvement in visualization of anastomotic site included 1 patient with liver cirrhosis secondary to portoenterostomy for congenital biliary dilatation and 1 patient, who was not eligible for the evaluation because of motion artifact caused by the difficulty of breath holding motion artifact. CONCLUSIONS: It was suggested that administration of DHCA could enhance the delineation of the anastomotic site on MRCP images.

A patient with adenocarcinoma of the jejunum successfully diagnosed by preoperative endoscopy for the small intestine.

In this study, the authors report the case of a 35-year-old man diagnosed preoperatively as having adenocarcinoma of the jejunum using a conventional endoscopy, usually used for the examination of the large intestine.

Clinical utility of peroral cholangioscopy for mucin-producing bile duct tumor.

BACKGROUND/AIMS: The purpose of this study was to examine the clinical utility of peroral cholangioscopy for mucin-producing bile duct tumor. METHODOLOGY: Peroral cholangioscopy was performed in seven cases of mucin-producing bile duct tumor to decide the course of treatment based on the results. All seven cases were evaluated by peroral cholangioscopy and examined by a transpapillary biopsy. Five out of the seven cases (71.4%) were adequately observed. Because abundant mucin could not be removed in 2 cases (28.6%), one of them underwent PTCS after PTBD, and the other had surgery for EBD insertion without PTBD at the patient's request. A stent was placed by surgery in five out of the seven cases and by a transpapillary method in two cases. RESULTS: Among the five cases that could be evaluated by peroral cholangioscopy, the excised specimens were compared with the findings obtained from peroral cholangioscopy in three cases that underwent surgery, while the results of transpapillary mapping biopsy were compared with the findings obtained from peroral cholangioscopy in two inoperable cases, showing that the evaluation by peroral cholangioscopy agreed with the results of tumor staging in all the five cases. CONCLUSIONS: This study suggested the possibility that the use of peroral cholangioscopy for mucin-producing bile duct tumor could be useful in deciding the course of treatment.

A new approach for diagnosis of hepatolithiasis: magnetic resonance cholangiopancreatography: potential usefulness of dehydrocholic acid (DHCA) administration in the evaluation of hepatolithiasis.

BACKGROUND/AIMS: The aim of this study was to investigate whether exogenous dehydrocholic acid (DHCA) was useful to enhance the delineation of hepatolithiasis. METHODOLOGY: Our study population comprised 9 patients. Magnetic resonance cholangiopancreatography (MRCP) was acquired before and after the administration of DHCA. Two different MRCP snap-shot techniques were applied: thick-slab two-dimensional (2D) (coronal) single shot turbo spin echo T2-weighted sequences and multisection thin-slab, 2D (coronal) single shot turbo spin echo T2-weighted sequences with three-dimensional (3D) maximum intensity projection (MIP) post processing. RESULTS: DHCA provided a better visualization of hepatolithiasis in 8 of 9 cases (88.9%). CONCLUSIONS: It was suggested that administration of DHCA could enhance the delineation of the hepatolithiasis on MRCP images.

Diagnostic value of MRCP and indications for ERCP.

BACKGROUND/AIMS: To assess the diagnostic value of magnetic resonance cholangiopancreatography (MRCP) and examine the indications for endoscopic retrograde cholangiopancreatography (ERCP). METHODOLOGY: MRCP was performed in 185 patients with hepatobiliary disease in whom abdominal ultrasonography (US) had not been of diagnostic value. These patients were selected for MRCP in view of their abdominal symptoms, high levels of hepatobiliary enzymes, and pancreatic/bile duct dilatation found by abdominal US. Based on MRCP findings, 75 patients were selected for ERCP. RESULTS: ERCP provided new findings in 14 (18.%) patients. In 110 patients subjected to only MRCP and follow-up as well as in 75 patients with MRCP followed by ERCP, MRCP-based diagnosis corresponded with the final diagnosis. In our study, patients who would have conventionally required ERCP, such as those with natural passed choledocholithiasis and postoperative bile duct dilatation, could be followed up without ERCP. These results the importance of considering indications for ERCP. CONCLUSIONS: MRCP can be an alternative to ERCP at least for diagnosis.

Increased number of mast cells in the dermis in actinic keratosis lesions effectively treated with imiquimod.

Actinic keratosis (AK) is a cutaneous cancer in situ which develops as a result of excessive exposure to ultraviolet (UV). Toll-like receptor (TLR)7 agonist imiquimod is a topical immune response modifier and is effective for the treatment of non-melanoma skin cancers. Recently, the diagnostic role of the dermatoscope has been reported in the course of treatment of AK. In addition, mast cells are now considered to contribute to both the innate and adaptive immune systems in topical imiquimod therapy. We assessed the effect of imiquimod treatment by dermatoscopic and immunohistochemical findings in 14 patients with a total of 21 AK lesions. With the dermatoscope, though the mean erythema score was not significantly different between the cured lesions and the unresponsive lesions, the erythema/red pseudo-network ("strawberry") pattern was decreased significantly in the cured lesions. By immunohistochemistry, the number of Ki-67-positive proliferative cells in the epidermis was decreased and that of CD117-positive mast cells in the dermis was increased in the responding lesions. To the best of our knowledge, this is the first study demonstrating that the number of mast cells in the dermis was increased in AK lesions effectively treated with imiquimod. Our present result suggests that mast cells may contribute an antitumor effect in human skin treated with topical imiquimod.

Increased nuclear localization of transcription factor Y-box binding protein 1 accompanied by up-regulation of P-glycoprotein in breast cancer pretreated with paclitaxel.

PURPOSE: The Y-box binding protein 1 (YB-1) regulates expression of P-glycoprotein encoded by the MDR1 gene. There have been no previous studies regarding the involvement of YB-1 in the development of resistance to paclitaxel. The present study was done to examine how paclitaxel affects the localization and expression of YB-1 in breast cancer. EXPERIMENTAL DESIGN: We evaluated the expression and localization of YB-1 and P-glycoprotein in breast cancer tissues obtained from 27 patients before and after treatment with paclitaxel. The effect of paclitaxel on localization of cellular YB-1 was examined by using GFP-YB-1. Interaction of YB-1 with the Y-box motif of the MDR1 promoters was studied by electrophoretic mobility shift assay. The effects of paclitaxel on MDR1 promoter activity were examined by luciferase assay. RESULTS: Of 27 breast cancer tissues treated with paclitaxel, nine (33%) showed translocation of YB-1 from the cytoplasm to the nucleus together with increased expression of P-glycoprotein during the course of treatment. Twelve breast cancer tissues (44%) showed neither translocation of YB-1 nor increased expression of P-glycoprotein. Nuclear translocation of YB-1 was correlated significantly with increased expression of P-glycoprotein (P=0.0037). Confocal analysis indicated that paclitaxel induced nuclear translocation of green fluorescent fused YB-1 in MCF7 cells. Furthermore, binding of YB-1 to the Y-box of MDR1 promoter was increased in response to treatment with paclitaxel. In addition, MDR1 promoter activity was significantly up-regulated by paclitaxel in MCF7 cells (P<0.001). CONCLUSIONS: The results of the present study suggested that YB-1 may be involved in the development of resistance to paclitaxel in breast cancer.