Clinical outcomes of second transurethral resection in non-muscle invasive high-grade bladder cancer: a retrospective, multi-institutional, collaborative study.

BACKGROUND: A retrospective, multi-institutional collaborative study was conducted to evaluate the impact of second transurethral resection (TUR) on the clinical outcome of non-muscle invasive high-grade bladder cancer and to identify predictors of invasion to the lamina propria (pT1) or deeper and residual tumor at the second TUR. METHODS: The clinical and pathological features of 198 patients with non-muscle invasive high-grade bladder cancer treated in five medical institutions from April 1990 to March 2013 were reviewed retrospectively. All patients underwent a second TUR within a mean of 1.5 months after the first resection. Clinicopathological findings of the first and second TURs were compared. Cancer-specific survival and recurrence-free survival were evaluated. Univariate and multivariate analyses for predictors of residual cancer at the second TUR were performed using a logistic regression model. RESULTS: At the second TUR, no tumor was found in 111 (56 %) patients, and 87 (44 %) had residual cancer. At the first TUR, five pT1 patients (3 %) were upstaged to pT2, one pTa patient (1 %) was upstaged to pT1, and 12 G2 patients (6 %) had their tumor upgraded to G3. Patients the group with less than stage pT1 cancer at the second TUR had significantly better survival than those in the group with stage pT1 or deeper cancer. Tumor multiplicity at the first resection was an independent risk factor for pT1 or deeper tumor at the second TUR. CONCLUSION: A second TUR is a valuable diagnostic procedure for accurate staging of non-muscle invasive high-grade bladder cancer. Tumor multiplicity at the first TUR was a significant independent predictor of pT1 or deeper tumor at the second TUR.

Validation of active surveillance criteria for pathologically insignificant prostate cancer in Asian men.

OBJECTIVES: To validate the ability of contemporary active surveillance protocols to predict pathologically insignificant prostate cancer among Asian men undergoing radical prostatectomy. METHODS: We retrospectively reviewed data on 132 patients eligible for any active surveillance criteria out of 450 patients that underwent radical prostatectomy at several institutions between 2006 and 2013. We validated the ability of seven contemporary active surveillance protocols to predict pathologically insignificant prostate cancer. Traditional and updated criteria to define pathologically insignificant prostate cancer were used. Predictive factors for pathologically insignificant prostate cancer were determined by logistic regression analysis. RESULTS: The predictive rate for updated pathologically insignificant prostate cancer of respective active surveillance criteria was 51% for Johns Hopkins Medical Institution, 41% for Prostate Cancer Research International: Active Surveillance Study, 39% for University of Miami, 32% for University of California, San Francisco, 32% for Memorial Sloan-Kettering Cancer Center, 31% for Kakehi and 27% for University of Toronto. Predictive rates for pathologically insignificant prostate cancer in Asian men were far lower than in USA men. On multivariate analysis, predictive factors of updated pathologically insignificant cancer was prostate volume (odds ratio 1.07, P = 0.004). By adding prostate volume to Prostate Cancer Research International: Active Surveillance Study criteria, the predictive rate for updated insignificant prostate cancer was improved up to 66.7%. CONCLUSIONS: Active surveillance can be carried out considering the clinical characteristics of prostate cancers depending on ethnicity, as current active surveillance criteria seem to have a lower predictive ability value of insignificant prostate cancer in Asian men compared with men in Western countries.

Nadir Testosterone after Long-Term Followup Predicts Prognosis in Patients with Prostate Cancer Treated with Combined Androgen Blockade.

PURPOSE: We examined the clinical significance of long-term serum testosterone monitoring to predict the prognosis of patients with prostate cancer treated with combined androgen blockade. MATERIALS AND METHODS: We retrospectively analyzed the records of 225 patients who underwent combined androgen blockade as first line therapy for prostate cancer. The prognostic values of testosterone and other clinical factors were evaluated with respect to prostate specific antigen progression-free and overall survival. RESULTS: Median patient age was 73.0 years, median prostate specific antigen was 42.6 ng/ml and median followup was 45.8 months. No variable associated with testosterone was predictive of progression-free survival. With regard to overall survival on univariate analysis nadir testosterone less than 16 ng/dl (p = 0.0190), less than 20 ng/dl (p = 0.0020) and less than 32 ng/dl (p = 0.0146) were significant together with other clinical factors. In contrast, nadir testosterone less than 8 and less than 12 ng/dl were not significant. Multivariate analysis showed that nadir testosterone less than 20 ng/dl was the significant prognostic factor (p = 0.0048). In addition, time to nadir testosterone was about 1 year (11.3 months). Patients were divided into rapid and slow types based on time to testosterone less than 20 ng/dl before and after 6 months, respectively. No significant difference in overall survival was observed between the 2 types. The current results suggest that the critical factor for prognosis was not a rapid decrease but whether nadir testosterone achieved a level of less than 20 ng/dl. CONCLUSIONS: Nadir testosterone 20 ng/dl was the most significant cutoff level for overall survival in Japanese patients with prostate cancer treated with combined androgen blockade.

Risk of New-Onset Dyslipidemia After Laparoscopic Adrenalectomy in Patients with Primary Aldosteronism.

BACKGROUND: Many patients with primary aldosteronism (PA) show a significant decline in kidney function after adrenalectomy. Thus, PA patients who undergo surgery are at greater risk of both postoperative renal damage and new-onset metabolic events associated with renal insufficiency. The aim of this study was to explore postoperative changes in serum lipid levels and to identify risk factors associated with postoperative new-onset dyslipidemia in PA patients. METHODS: The records of 57 Japanese patients who underwent unilateral laparoscopic adrenalectomy for PA were retrospectively surveyed. Clinical and biochemical data were evaluated at baseline and 12 months after surgery. Preoperative and postoperative estimated glomerular filtration (eGFR) and serum lipid profile, including triglycerides, high-density lipoprotein (HDL)-cholesterol and low-density lipoprotein (LDL)-cholesterol levels, were compared. Furthermore, uni- and multivariate analyses were performed to determine the predictors for postoperative new-onset dyslipidemia. RESULTS: A significant decrease in eGFR and deterioration of serum lipid levels was identified postoperatively in most patients. Of the 39 patients without pre-existing dyslipidemia, 18 developed new-onset dyslipidemia postoperatively. Multivariate analysis identified preoperative lower eGFR and higher body mass index as independent predictors for new-onset dyslipidemia after surgery. On univariate analyses, additional factors associated with new-onset dyslipidemia included older age, male sex, higher LDL-cholesterol, and higher LDL/HDL ratio. CONCLUSIONS: PA patients had a higher risk of postoperative new-onset or progressive dyslipidemia. Clinicians should pay attention to not only follow-up of renal impairment but also total management of new-onset metabolic events associated with renal insufficiency in PA patients.

The association of CXCR3 and renal cell carcinoma metastasis.

PURPOSE: Renal cell carcinoma expresses CXCR3 but the function of CXCR3 in renal cell carcinoma has not been clarified. We explored the function of CXCR3 in renal cell carcinoma and investigated CXCR3 regulating factors. MATERIALS AND METHODS: We obtained 56 clinical samples of clear cell renal cell carcinoma and corresponding normal renal tissue samples from the surgical specimens of Japanese patients who underwent radical nephrectomy at Chiba University Hospital between 2000 and 2011. As renal cell carcinoma cell lines, we used 786-O, ACHN and Caki-1. The expression profiles of CXCR3 and its splice variants were examined. For functional analyses 786-O and interferon-γ inducible 10 kDa protein or IP-10 (CXCL10) were selected as representatives. RESULTS: CXCR3 and its ligands were abundant in renal cell carcinoma samples compared to corresponding normal kidney samples. The CXCR3-A-to-CXCR3-B ratio was 1.5 times higher in renal cell carcinoma samples than in normal kidney samples. CXCL10 treatment induced 786-O cell migration and invasion, and these effects were inhibited by neutralizing antibody. Phosphorylated RhoA and pro/active matrix metalloproteinase-9 expression was up-regulated by CXCL10 treatment. In clinical samples CXCR3 and CXCR3-A expression was significantly higher in metastatic than in nonmetastatic carcinoma samples. Finally, the expression of CXCR3-A and HIF-1α correlated significantly in clinical samples. In 786-O treatment with CoCl2 up-regulated CXCR3 and HIF-1α expression 4.5 and 2.2-fold, respectively. CONCLUSIONS: We determined the association of CXCR3 and renal cell carcinoma metastasis. CXCR3 expression may be regulated by hypoxia.

Development of a nomogram for predicting the stone-free rate after transurethral ureterolithotripsy using semi-rigid ureteroscope.

OBJECTIVES: To develop and to internally validate a novel nomogram for predicting the stone-free rate after transurethral ureterolithotripsy. METHODS: A total of 412 patients with 534 ureteral stones were treated with transurethral ureterolithotripsy using semi-rigid ureteroscopes. Treatment efficacy was evaluated 3 months after the procedure. Multivariate stepwise logistic regression analysis was used to identify independent predictors of being stone-free in the model-building set. A total of 427 stones (80% of 534) were randomly allocated for identification and statistical analysis to build the model, and the remaining 107 (20%) were used for cross-validation. A nomogram for the stone-free rate was developed based on the final logistic regression model. RESULTS: Stone length, number of stones, stone location and the presence of pyuria were independent factors related to the stone-free rate after transurethral ureterolithotripsy treatment, and these were used to develop a nomogram. In this nomogram, the area under the receiver operating characteristic curve was 0.7432 for the nomogram, 0.5641 for stone size, 0.5908 for the number of stones, 0.6594 for stone location and 0.6076 for pyuria. Validation using 20% of the data also achieved a reasonable predictive accuracy (area under the receiver operating characteristic curve = 0.682). CONCLUSIONS: The first nomogram for predicting the stone-free rate after transurethral ureterolithotripsy was developed. It has a reasonable predictive accuracy, and in combination with extracorporeal shock wave lithotripsy nomograms, it might be useful for deciding treatment methods.

Preoperative masked renal damage in Japanese patients with primary aldosteronism: identification of predictors for chronic kidney disease manifested after adrenalectomy.

OBJECTIVE: Correct interpretation of renal function in patients with primary aldosteronism is difficult before adrenalectomy, because subtle kidney impairment is often masked by glomerular hyperfiltration peculiar to primary aldosteronism. The aim of this study was to investigate postoperative changes in renal function for patients with primary aldosteronism and to identify clinical predictors of chronic kidney disease manifested postoperatively in the patients without pre-existing chronic kidney disease. METHODS: Records of 78 Japanese patients who underwent unilateral adrenalectomy for primary aldosteronism were retrospectively surveyed. Patients who had been followed up for <6 months were excluded. Preoperative and postoperative estimated glomerular filtration rate were compared. Furthermore, uni- and multivariate analyses were carried out to identify clinical predictors for chronic kidney disease manifested postoperatively. RESULTS: Patients with preoperative estimated glomerular filtration rate ≥60 mL/min/1.73 m(2) showed a significant decrease after surgery. Of the 66 patients without pre-existing chronic kidney disease, 24 developed chronic kidney disease postoperatively. Multivariate logistic regression analysis identified a medical history of dyslipidemia as an independent predictor for chronic kidney disease manifested postoperatively. According to univariate analyses, additional factors associated with postoperative manifestation of chronic kidney disease included older age, lower diastolic blood pressure and lower estimated glomerular filtration rate. CONCLUSIONS: The interpretation of normal or abnormal renal functions by examining estimated glomerular filtration rate heightened by hyperfiltration alone can mislead clinicians before adrenalectomy. Clinicians should pay attention to patients at greater risk of a significant decline in postoperative renal function.

[Treatment outcome of intrarenal Bacillus Calmette-Guerin therapy for carcinoma in situ of the upper urinary tract].

We investigated the long-term efficacy and safety of intrarenal bacillus Calmette-Guerin (BCG) therapy for carcinoma in situ (CIS) of the upper urinary tract. We retrospectively reviewed the medical records of 9 patients who underwent BCG perfusion therapy for CIS of the upper urinary tract from January 2005 to December 2011 at our institute. All patients were treated by retrograde catheterization using a 6 Fr double- J ureteric stent. BCG at half the dose (40.5 mg or 40 mg) in 40ml saline was instilled into the bladder weekly for 6 or 8 weeks as one course. The mean follow-up period was 32.7 months (range 4-75 months). In all patients (100%), cytology became negative after one course of BCG perfusion and 8 patients (88. 9%) remained disease-free for a median follow-up of 35.1 months. Among these 9 patients, 1 patient showed recurrence after 6 months of the first BCG therapy. The patient received a second course of BCG therapy, but the patient developed invasive tumor and distant metastases. Two patients could not continue the treatment due to pyelonephritis. In conclusion, although longer follow up and further experience with treatment for CIS of the upper urinary tract are required, this treatment is considered to be effective and safe.

External validation of a pre-operative prognostic nomogram for renal cell carcinoma in two patient populations: a retrospective cohort study.

The aim of this study was to establish the discriminating accuracy of Kanao's pre-operative nomogram for renal cell carcinoma in predicting cause-specific survival among representative patients who underwent nephrectomy. Patients originated from two centers: Chiba University Hospital (n= 151) and Chiba Cancer Center (n = 91). We validated the predictive accuracy, which was assessed using Harrell's concordance-index. The concordance-index values were 0.692 and 0.834 for Chiba University Hospital and Chiba Cancer Center, respectively, although it was 0.822 for the combined data sets. Results of external validation were different at each cohort. We constructed calibration plots of Kanao's nomogram and confirmed the tendency at each institution. Inconsistency of results among two centers makes it difficult to reach a valid conclusion. Therefore, the predictive accuracy of Kanao's nomogram was not settled. Clinicians need to confirm the predictive accuracy of Kanao's nomogram and construct calibration plots when applying this nomogram to different patient populations.

Prognostic models for renal cell carcinoma recurrence: external validation in a Japanese population.

The aim of the present study was to compare the accuracy of three prognostic models in predicting recurrence-free survival among Japanese patients who underwent nephrectomy for non-metastatic renal cell carcinoma (RCC). Patients originated from two centers: Chiba University Hospital (n = 152) and Chiba Cancer Center (n = 65). The following data were collected: age, sex, clinical presentation, Eastern Cooperative Oncology Group performance status, surgical technique, 1997 tumor-node-metastasis stage, clinical and pathological tumor size, histological subtype, disease recurrence, and progression. Three western models, including Yaycioglu's model, Cindolo's model and Kattan's nomogram, were used to predict recurrence-free survival. Predictive accuracy of these models were validated by using Harrell's concordance-index. Concordance-indexes were 0.795 and 0.745 for Kattan's nomogram, 0.700 and 0.634 for Yaycioglu's model, and 0.700 and 0.634 for Cindolo's model, respectively. Furthermore, the constructed calibration plots of Kattan's nomogram overestimated the predicted probability of recurrence-free survival after 5 years compared with the actual probability. Our findings suggest that despite working better than other predictive tools, Kattan's nomogram needs be used with caution when applied to Japanese patients who have undergone nephrectomy for non-metastatic RCC.

Influence of visceral obesity on oncologic outcome in patients with renal cell carcinoma.

OBJECTIVE: At present, computed tomography (CT) is used in almost all patients with renal tumors. We aimed to investigate the relationship between visceral adipose tissue (VAT), as assessed by CT, and various other factors in patients with renal cell carcinoma (RCC). METHODS: We undertook an examination of VAT in 117 male patients undergoing nephrectomy or partial nephrectomy at Chiba University Hospital using software designed to detect VAT in the horizontal plane of the body cavity. Pathological stage, microvascular invasion, tumor grade, performance status, C-reactive protein, BMI, hypertension, hyperlipemia, hyperglycemia, history of smoking and cause-specific survival rate were examined in relation to VAT, and multivariate Cox regression analysis was used to determine significant predictors of cause-specific survival. RESULTS: VAT in patients with stage I disease was significantly greater than that in patients with more advanced disease (p = 0.0219). VAT in patients with microvascular invasion was significantly smaller than in those without microvascular invasion (p = 0.0260). Patients with high VAT had significantly higher cumulative cause-specific survival when compared to patients with low VAT (p = 0.0257). CONCLUSION: VAT was associated with better clinical features in patients with RCC. Further study is necessary in order to clarify the role of VAT in RCC.

Treatment outcomes of sorafenib for first line or cytokinerefractory advanced renal cell carcinoma in Japanese patients.

The objective of the present study was to document the treatment efficacy and safety of sorafenib in Japanese patients with advanced renal cell carcinoma (RCC). A retrospective analysis of 50 consecutive patients with metastatic RCC between January 2005 and December 2009 was carried out. Patients received sorafenib after failed cytokine therapy or first-line sorafenib treatment. All received 400 mg of sorafenib orally twice daily. Five of 14 patients with bone metastases were also given bisphosphonates. Tumor response was evaluated every 1-2 months according to the Response Evaluation Criteria in Solid Tumors. Adverse events (AE) were evaluated at each visit during and after treatment, and were recorded according to the National Cancer Institute's Common Terminology Criteria for Adverse Events version 3.0. Dose modification of sorafenib was permitted if grade 3 or 4 AE occurred. Treatment continued until disease progression or treatment intolerance occurred. Partial response, and stable disease as best objective responses were observed in 11 (22%) and 23 (46%) patients, respectively. Median progression-free survival was 7.3 months and median overall survival was 11.9 months. All patients experienced AE and one or more grade 3/4 AE occurred in 43 of 50 (86%) patients. Although it requires close monitoring, sorafenib treatment seemed to be effective in the present study population.

Association between serum sex hormone levels and prostate cancer: effect of prostate cancer on serum testosterone levels.

Androgens are essential for prostatic growth and development, but also play a significant role in the pathogenesis of prostate disease. The traditional view that higher testosterone levels represent a risk factor for prostate cancer (PCa) appears to have little evidentiary support. Some studies have described a relationship between lower testosterone levels and more advanced disease. Serum androgen levels, within a broad range, are thus suggested to show no association with PCa risk, whereas low rather than high serum testosterone levels have been found to be associated with advanced or high-grade disease at the time of PCa diagnosis. Dihydrotestosterone, the principal prostatic androgen, is transformed from testosterone by type 1 and type 2 5alpha-reductase, and therapeutic benefits may thus be potentially achieved through the inhibition of 5alpha-reductase.

Combination of gemcitabine and paclitaxel as second-line chemotherapy for advanced urothelial carcinoma.

OBJECTIVE: The aim of this study was to evaluate the efficacy and toxicities of the gemcitabine and paclitaxel combination regimen as second-line chemotherapy for patients with advanced or metastatic urothelial carcinoma (UC) who have previously been treated with platinum-based chemotherapy for the metastatic disease. METHODS: Thirty-three patients with advanced or metastatic UC who had received platinum-based chemotherapy were treated with an outpatient gemcitabine and paclitaxel combination regimen. A dose of 180 mg/m(2) paclitaxel was administered by intravenous (IV) infusion on Day 1, and 1000 mg/m(2) gemcitabine was administered by IV on Days 1, 8 and 15.The course was repeated every 28 days. Patients were evaluated after every 2 cycles of therapy using computed tomography. RESULTS: Of the 33 patients enrolled in this study, 30 could be evaluated to determine treatment efficacy; 10 had an objective response [overall response rate: 33.3%, 95% confidence interval (CI), 19.2-51.2%]. The median overall survival was 11.3 months (95% CI, 7.2-13.6 months). The chemotherapy sensitivity differed with disease site. The response rates of lung and bone metastases were 27% and 14%, and the progressive disease (PD) rates of lung and bone metastases were 13% and 14%, respectively. On the other hand, the response rate of liver metastasis was 14%, and its PD rate was 57%. None of the patients (n = 3) with adrenal metastasis responded to this regimen. Toxicities were mild, and no life-threatening complications occurred. CONCLUSIONS: Gemcitabine and paclitaxel combination therapy is a tolerable and active regimen for patients with advanced UC after failure of platinum-based chemotherapy.

Neuroendocrine differentiation in the progression of prostate cancer.

Neuroendocrine (NE) cells originally exist in the normal prostate acini and duct, regulating prostatic growth, differentiation and secretion. Clusters of malignant NE cells are found in most prostate cancer (PCa) cases. NE differentiation (NED) is the basic character of the prostate, either benign or malignant. NE cells hold certain peptide hormones or pro-hormones, which affect the target cells by endocrine, paracrine, autocrine and neuroendocrine transmission in an androgen-independent fashion due to the lack of androgen receptor. NED is accessed by immunohistochemical staining or measurement of serum levels of NE markers. The extent of NED is associated with progression and prognosis of PCa. Chromogranin A (CGA) is the most important NE marker. In metastatic PCa, pretreatment serum CGA levels can be a predictor for progression and survival after endocrine therapy. It is recommended to measure longitudinal change in serum CGA. The NE pathway can also be a therapeutic target.

Usefulness of panoramic views for novice surgeons doing retroperitoneal laparoscopic nephrectomy.

OBJECTIVES: Laparoscopic surgery is widely accepted for managing renal disease. Thus, the system used to educate and train novice surgeons in laparoscopic surgery becomes important to reduce the risks of surgery during their training. A prospective study was carried out to determine the usefulness of using panoramic views during laparoscopic surgery. METHODS: Between April 2004 and March 2007, four novice surgeons started learning laparoscopic radical nephrectomy: two carried out surgery without panoramic views and two used panoramic views. Operating time and blood loss for the initial 10 cases of each surgeon were compared. Panoramic views were obtained by interlacing each video frame of the video images electronically; the images were then processed and displayed during each step of laparoscopic surgery. RESULTS: Panoramic, real-time views could be obtained, and they served as navigation maps. The learning curve of surgeons using the panoramic views was shorter than that of surgeons who did not use panoramic views. Time to ligation of renal artery from port placement and the operating time was shorter (69.0 +/- 21.5 min vs 106.8 +/- 44.9 min, P = 0.0016, 212 +/- 42 min vs 254 +/- 46 min, P = 0.0489, respectively) and the estimated blood loss was less for the surgeons who used panoramic views (87 +/- 109 mL vs 334 +/- 268 mL, P = 0.0005). CONCLUSION: Panoramic views during laparoscopic surgery shortened operating time and reduced blood loss, indicating their usefulness in assisting novice surgeons to carry out procedures safely and accurately.

The role of testosterone in the pathogenesis of prostate cancer.

Relationships between androgenic hormones and prostatic tissue growth are complex. It is certainly true that the prostate will not develop without androgens and the gland will atrophy if androgen support is withdrawn. The hormonal hypothesis remains one of the most important hypotheses in the etiology of prostate cancer (PCa), and efforts are continuing to improve the understanding of androgen actions in PCa. Although evidence from epidemiological studies of associations between circulating levels of androgens and PCa risk has been inconsistent, the traditional view that higher testosterone (T) levels represent a risk factor for PCa appears to have little evidentiary support. Reinvestigation of the relationship between T and PCa seems important and necessary if a new, clinically and scientifically rewarding concept is to be constructed. The present review considers the metabolism and intraprostatic action of T, epidemiological evidence, and the association between T and PCa risk.

Renal cell carcinoma with a huge solitary metastasis to the contralateral adrenal gland: a case report.

Renal cell carcinoma (RCC) is capable of metastasizing to several organs. Synchronous isolated contralateral adrenal metastasis of the primary RCC is, however, very rare. Herein we report a case of RCC with a huge solitary metastasis to the contralateral adrenal gland that was surgically treated. We scheduled nephrectomy for the left primary RCC and adrenalectomy for the right adrenal tumor. However, at surgery we found a huge right adrenal tumor that had invaded the right kidney, right renal vein, and inferior vena cava. Therefore right nephrectomy was performed simultaneously with resection and reconstruction of the inferior vena cava. Pathological findings demonstrated that the left renal tumor and right adrenal tumor had the same histology. Although the patient required hemodialysis, he remains well at six months postoperatively. So far, there have been only two cases of a solitary contralateral metastatic adrenal tumor that was larger than the primary RCC, thus the present case is the third one.

Functional evidence for a metastasis suppressor gene for rat prostate cancer within a 60-kilobase region on human chromosome 8p21-p12.

We recently demonstrated that the human chromosome 8p21-p12 region encodes a metastasis suppressor gene for rat prostate cancer. The presence of this region suppresses the metastatic ability of rat prostate cancer cells (N. Nihei et al., Genes Chromosomes Cancer, 17: 260-268, 1996). To define further the region harboring the metastasis suppressor gene, a truncated human chromosome 8 containing this region was transferred into highly metastatic AT6.3 rat prostate cancer cells by microcell-mediated chromosome transfer. The region of human chromosome 8 retained in each microcell hybrid was determined by a PCR analysis with sequence-tagged site markers, and this analysis placed the metastasis suppressor gene in the interval between D8S2249 and D8S2244 on human chromosome 8p21-p12. One of the metastasis-suppressed microcell hybrids was used for construction of representative yeast/bacterial artificial chromosome (YAC/BAC) library covering the candidate region using a transformation-associated recombination technology (N. Kouprina et al., Genomics, 53: 21-28, 1998). The final contig corresponding to the candidate region was assembled by four YAC/BAC clones. Each clone was transfected into the AT6.3 cells, and the resultant transfectants were tested for their metastatic ability in athymic nude mice. Introduction of a 60-kb YAC/BAC clone resulted in significant suppression of the metastatic ability without suppression of the tumorigenicity. In contrast, other YAC/BAC clones in the contig had neither metastasis nor tumor suppressor activity. This demonstrates that the 60-kb fragment from the human chromosome 8p21-p12 region contains the metastasis suppressor gene for the AT6.3 cells. Frequent loss of heterozygosity of this region is detected in human prostate cancer, which suggests that our target metastasis suppressor gene may also play an important role in the progression of human prostate cancer.