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Taiji Tsukamoto

Publications and source records attributed to Taiji Tsukamoto.

At least 73 records · Page 4Linked to original sources

[Tumor size and regional lymph node metastasis in patients with M0 renal cell carcinoma: analysis in those having regional lymph node dissection].

We evaluated the relationship between regional lymph node metastasis and tumor size in patients with M0 renal cell carcinoma who received regional lymph node dissection. The study involved 234 of the 247 patients with localized renal cell carcinoma who underwent radical nephrectomy with lymph node dissection at our institute between 1985 and 1999. Patients were arbitrarily classified into 3 groups by the greatest diameter of the tumor on preoperative computed tomography (CT): 4.0 cm or less (group A), 4.1 to 7.0 cm (group B), and 7.1 cm or more (group C). The incidence of lymph node metastasis was assessed in each group. The current study showed that 11 (4.7%) of the 234 patients with lymph node dissection together with radical nephrectomy were lymph node positive. The incidences of lymph node metastasis were 4.0% in group A, 2.3% in group B, and 8.4% in group C (p = 0.79). Of these 11 patients with lymph node metastasis, 2 (18.2%) have so far survived for over 5 years following surgery. Although the role of regional lymph node dissection with radical nephrectomy might be limited and controversial in renal cell carcinoma, urological surgeons should always be aware of possible metastasis for any tumor size.

Adult↗

Transrectal high-intensity focused ultrasound in the treatment of localized prostate cancer: a multicenter study.

We report a multicenter trial with transrectal high-intensity focused ultrasound (HIFU) in the treatment of localized prostate cancer. A total of 72 consecutive patients with stage T1c-2NOM0 prostate cancer were treated using the Sonablate 500TM HIFU device (Focus Surgery, Indianapolis, USA). Biochemical recurrence was defined according to the criteria recommended by the American Society for Therapeutic Radiology and Oncology Consensus Panel. The median age and prostate specific antigen (PSA) level were 72 years and 8.10 ng/ml, respectively. The median follow-up period for all patients was 14.0 months. Biochemical disease-free survival rates in all patients at 1 and 2 years were 78% and 76%, respectively. Biochemical disease-free survival rates in patients with stage T1c, T2a and T2b groups at 2 years were 89, 67% and 40% (p = 0.0817). Biochemical disease-free survival rates in patients with Gleason scores of 2-4, 5-7 and 8-10 at 2 years were 88, 72% and 80% (p = 0.6539). Biochemical disease-free survival rates in patients with serum PSA of less than 10 ng/ml and 10-20 ng/ml were 75% and 78% (p = 0.6152). No viable tumor cells were noted in 68% of patients by postoperative prostate needle biopsy. Prostatic volume was decreased from 24.2 ml to 14.0 ml at 6 months after HIFU (p < 0.01). No statistically significant differences were noted in International Prostate Symptom Score, maximum urinary flow rate and quality of life analysis with Functional Assessment of Cancer Therapy. HIFU therapy appears to be minimally invasive, efficacious and safe for patients with localized prostate cancer with pretreatment PSA levels less than 20 ng/ml.

Adult↗

[Ejaculatory disorder by alpha-1 adrenoceptor antagonist in patients with benign prostatic hyperplasia; retrospective comparison between naftopidil and tamsulosin].

We cross-sectionally studied the incidence and impact on quality of life of ejaculatory disorders caused by alpha-1 adrenoceptor antagonists (tamsulosin or naftopidil) in patients with benign prostatic hyperplasia (BPH). By questionnaire, we queried 88 clinical BPH patients concerning ejaculatory disorders, who were treated with tamsulosin or naftopidil between February 1999 and August 2003. We investigated the difference in the incidence and types of disorders between the two drugs. Of the 88 patients, 63 (71.6%) had sexual activities during the treatment. The incidence of ejaculatory disorders was significantly higher in the tamsulosin group (30.0%) than in the naftopidil group (3.0%). Eighty percent of patients having the disorders noticed the absence or reduced volume of semen although they experienced orgasms. The median quality of life index concerning the disorder was rated as 4, "mostly dissatisfied." Our results indicated that ejaculatory disorders occurred more frequently in the tamsulosin group. We should inform patients about this adverse effect caused by alpha-1 adrenoceptor antagonists prior to treatment.

Adrenergic alpha-1 Receptor Antagonists↗

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2003). I. Susceptibility distribution].

The bacterial strains isolated from 565 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2003 and July 2004. The susceptibilities of them to many kinds of antimicrobial agents were investigated. Of them, 701 strains were estimated as prophlogistic bacteria and used for the investigation. The strains consisted of 258 Gram-positive bacterial strains (36.8%) and 443 Gram-negative bacterial strains (63.2%). Against Staphylococcus aureus, vancomycin (VCM) showed the strongest activity and prevented the growth of all strains with 2 microg/mL. Against Streptococcus agalactiae, ampicillin (ABPC), cefozopran (CZOP), imipenem (IPM), and clarithromycin (CAM) showed a strong activity and the MIC90 was 0.125 microg/mL or less. Against Enterococcus faecalis, VCM, ABPC, and IPM showed a strong antibacterial activity. The antibacterial activity of cephems to Escherichia coli was generally good, and especially CZOP and cefpirome (CPR) showed the strongest activity (MIC90: < or = 0.125 microg/mL). Quinolone resistant E. coli [MIC of ciprofloxacin (CPFX): > or =4 microg/mL] was detected at frequency of 15.7%, which was higher than that in the last year. Against Klebsiella pneumoniae, meropenem (MEPM) showed the strongest activity and next, the antibacterial activity of CRMN and CZOP was good. The antibacterial activity of the other cephems, however, significantly decreased, compared with that evaluated in last year. Against Serratia marcescens, MEPM had the strongest antibacterial activity. Against Proteus mirabilis, MEPM and CRMN showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. Nest, cefmenoxime (CMX), ceftazidime (CAZ), cefixime (CFIX), cefpodoxime (CPDX), CPR, CZOP, and cefditoren (CDTR) showed a strong activity. The antibacterial activity of the drugs to Pseudomonas aeruginosa was generally low, and MIC90 of all the drugs was ranged from 32 to < or = 256 microg/mL except IPM and amikacin (AMK) having 16 microg/mL. The antibacterial activity of CZOP was relatively good (MIC50: 2 microg/mL).

Drug Resistance, Microbial↗

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2003). II. Background of patients].

Seven hundred and nineteen bacterial strains isolated from 565 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2002 and July 2003. The frequency of bacteria isolation divided with patient clinical background was compared. The clinical background investigated included sex, age, type of infections, timing of antibiotics administration, and presence or absence of surgery affecting a decrease in defense against infection. The bacterial strains were divided with the age and sex of the patients and the types of infections. In males, the number of patients aged less than 50 years was few and the complicated UTIs without indwelling catheter was observed most frequently. Number of patients aged 20-39 years was greater in female than male. In all of ages except 0-9 and 70-79 years, the ratio of the uncomplicated UTIs was high, accounting for 44.4-91.7% of all types of infections. In the present time, the bacteria most frequently isolated were Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis also were relatively frequently isolated. E. coli was most frequently isolated from the uncomplicated UTIs, and P. aeruginosa and E. faecalis were frequently isolated from the complicated UTIs with indwelling catheter. With respect to the relation of these results to the age of the patients, in the uncomplicated UTIs, the isolation frequency of E. coli was the highest in all age groups, accounting for 40% or higher. In the complicated UTIs without indwelling catheter, the isolation frequency of E. coli decreased with aging of the patients but still was the highest in all age groups. In the complicated UTIs with indwelling catheter, the isolation frequency of E. coli was lower than in the uncomplicated UTIs in all age groups and P. aeruginosa and E. faecalis were more frequently isolated. In comparison of causative bacteria in UTIs between before and after the administration of antibiotics, P. aeruginosa increased after the administration in any types of UTIs. In comparison of causative bacteria in UTIs with or without surgery, E. coli was more frequently isolated in the patients without surgery, while P. aeruginosa and E. faecalis were more frequently isolated in the patients with surgery in any UTIs.

Adolescent↗

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2003). III. Secular changes in susceptibility].

The bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa) isolated from 565 patients diagnosed as urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2003 and July 2004. The susceptibilities of these bacteria to various antimicrobial agents were examined. The bacteria were divided into 2 groups consisting of uncomplicated UTIs and complicated UTIs (with and without indwelling catheter) based on their isolation origins. The results were compared with those obtained between 1994 and 2002. The drug sensitivity of S. aureus in this year was similar to those in up to the previous years and S. aureus showed the best susceptibility to vancomycin. The drug sensitivity of E. faecalis in this year also was similar to those in up to the previous years. The drug sensitivity of E. coli in this year was generally good except penicillins and was similar to those in up to the previous years. Among cephems, cefozopran (CZOP) and cefpirome (CPR) showed the highest potency activity (MIC90: < or = 0.125 microg/mL). An antibacterial activity of cefotiam (CTM) was stable for 10 years and was fine (MIC0: < or = 0.5 microg/mL). The sensitivity of E. coli to carbapenems and carumonam (CRMN) also was good like to CZOP. The sensitivity of the complicated UTIs group to quinolones, however, has decreased after 2000 and it was suggested that the resistance to the drug has developed. Kiebsiella spp. showed a decrease in the susceptibility to some of cephems. The drugs indicating a big decrease in the sensitivity were cefazolin, CTM, cefaclor, and cefpodoxime. Imipenem, carbapenems, also indicated a decrease in the sensitivity. The susceptibility of the strain to the other drugs was similar to that in up to the previous years. Among them, CZOP maintained good susceptibility (MIC90: > or = 0.125 microg/mL against uncomplicated UTIs, 0.25 microg/mL against complicated UTIs) like meropenem. The drug sensitivity of P. aeruginosa was generally low and was not much different from that in up to the previous years.

Anti-Infective Agents↗

HPC2/ELAC2 polymorphism associated with Japanese sporadic prostate cancer.

BACKGROUND: HPC2/ELAC2 gene was identified by linkage analysis from familial prostate cancer (Pca) patients in USA. To determine the association of HPC2/ELAC2 gene with Japanese sporadic Pca, we performed a case-control study focused on two missense polymorphisms. METHODS: We genotyped the two polymorphic sites of Ser217Leu and Ala541Thr in sporadic Japanese Pca patients (n = 285) and matched controls (n = 233). Controls were unrelated Japanese outpatients who had no history of any cancer and normal PSA level (less than 4.0 ng/ml). Statistical analyses were performed by Mann-Whitney's U-test, Fisher's exact test, and logistic regression analysis. RESULTS: We observed a significantly higher frequency of the Thr allele at 541 polymorphic site in Pca patients (8.4%) compared to the control group (2.1%) (P = 0.0030, Odds Ratio (OR) = 4.02, 95% CI = 1.50-10.8). However, this SNP does not correlate with clinical stage, PSA level, Gleason score of biopsies or age at diagnosis. No association was identified at Ser217Leu polymorphic site. CONCLUSIONS: Our results indicate that Thr allele at 541 in HPC2/ELAC2 has strong significance in the predisposition of sporadic Pca in Japan. This polymorphism can be useful to predict the personal Pca risk, which lead the effective screening of Pca.

Aged↗

NE-10 neuroendocrine cancer promotes the LNCaP xenograft growth in castrated mice.

Increases in neuroendocrine (NE) cells and their secretory products are closely correlated with tumor progression and androgen-independent prostate cancer. However, the mechanisms by which NE cells influence prostate cancer growth and progression, especially after androgen ablation therapy, are poorly understood. To investigate the role of NE cells on prostate cancer growth, LNCaP xenograft tumors were implanted into nude mice. After the LNCaP tumors were established, the NE mouse prostate allograft (NE-10) was implanted on the opposite flank of these nude mice to test whether NE tumor-derived systemic factors can influence LNCaP growth. Mice bearing LNCaP tumors with or without NE allografts were castrated 2 weeks after NE tumor inoculation, and changes in LNCaP tumor growth rate and gene expression were investigated. After castration, LNCaP tumor growth decreased in mice bearing LNCaP tumors alone, and this was accompanied by a loss of nuclear androgen receptor (AR) localization. In contrast, in castrated mice bearing both LNCaP and NE-10 tumors, LNCaP tumors continued to grow, had increased levels of nuclear AR, and secreted prostate-specific antigen. Therefore, in the absence of testicular androgens, NE secretions were sufficient to maintain LNCaP cell growth and androgen-regulated gene expression in vivo. Furthermore, in vitro experiments showed that NE secretions combined with low levels of androgens activated the AR, an effect that was blocked by the antiandrogen bicalutamide. Because an increase in AR level has been reported to be sufficient to account for hormone refractory prostate cancers, the NE cell population ability to increase AR level/activity can be another mechanism that allows prostate cancer to escape androgen ablation therapy.

Androgens↗

Modulation of phenotype of human prostatic stromal cells by transforming growth factor-betas.

BACKGROUND: We investigated the effects of transforming growth factor (TGF)-betas on morphological and receptor phenotypes, as well as proliferation of four currently established human prostatic myofibroblast cell lines and one commercially available prostatic stromal cell line. METHODS: The effects of TGF-betas on morphological changes and proliferation of the cells were studied by immunohistochemistry and bromodeoxyuridine assay, respectively. The expression of alpha 1-receptor subtypes was measured by real time quantitative reverse transcription-polymerase chain reaction (RT-PCR) and the radioligand binding assay for the receptors was also performed. RESULTS: TGF-betas 1, 2, and 3 induced expression of desmin and myosin of cells of the established cell lines, and significantly inhibited their growth. The alpha 1a-receptor was expressed only in the commercially available cell line and alpha 1b and 1d, in all cell lines. TGF-beta 1 suppressed the expression of all three subtypes of the alpha 1-receptor. The binding sites of cells of all the cell lines were reduced by treatment with this growth factor. CONCLUSIONS: TGF-betas may induce human prostatic stromal cells to express the smooth muscle phenotype and inhibited their growth. However, the growth factor reduced the binding sites of the receptor and suppressed mRNA expression of its subtypes, suggesting that morphological and receptor phenotypes may be regulated via more than one pathway by TGF-beta(s).

Cell Division↗

Lack of the complete circular rhabdosphincter and a distinct circular smooth muscle layer around the proximal urethra in elderly Japanese women: an anatomical study.

Histological observations of semiserial sections obtained from the cadavers of 30 elderly Japanese women (aged 61-93 years) found that the urethral rhabdosphincter (URS) usually occurred as a ventrally localized structure instead of exhibiting the normal completely circular configuration. The superoinferior length, thickness and muscle fiber density of the URS area showed significant interindividual variation. A thick fascicle, extending posterolaterally from the URS and radiating to the lateral vaginal wall and other perineal tissues, was usually observed. A circular smooth muscle layer, which immediately surrounded the longitudinal smooth muscle layer, was consistently present in the proximal urethral but not in the bladder neck. These findings suggest that voluntary sphincteric action is weak or incomplete in elderly Japanese women. We therefore hypothesize that upward retraction of the midurethra by the URS, compression of the distal urethra by its posterolateral extensions, and tonus provided by the outer circular smooth muscle layer all contribute to maintaining continence in these women.

Aged↗

Incidence of sexually transmitted diseases in Hokkaido, Japan, 1998 to 2001.

The objective of this study was to provide precise data on the incidence of sexually transmitted diseases (STDs) in Hokkaido. The goal of this prospective surveillance, study was to clarify the STD incidence between 1998 and 2001 in Hokkaido, Japan. The incidence of gonococcal infection in men was found to be 127-199 per 100 000 people per year, which was three or four times higher than that for women. Female genital chlamydial infection had an incidence of 300-400 with a female to male ratio of two or three to one. Younger adults had higher incidences of gonococcal and chlamydial infections than older people. In conclusion, the current study of STDs revealed high incidences of gonococcal and chlamydial infections in the Hokkaido area, and there was no decreasing trend in STD incidence during these 4 years.

Adolescent↗

Prophylactic antimicrobial agents in urologic laparoscopic surgery: 1-day versus 3-day treatments.

Although the incidence of surgical site infection (SSI) is generally low in laparoscopic urologic surgery, the standard protocol for prophylactic use of antimicrobial agents remains to be established. We retrospectively compared the incidence and severity of SSI after laparoscopic surgery between two different protocols for prophylactic use of antimicrobial agents. This study included 114 patients who underwent urologic laparoscopic surgery categorized as "clean" or "clean-contaminated" in Sapporo Medical University School Hospital between January 1996 and October 2002. As a prophylactic antimicrobial agent, one of the cephalosporins or penicillins was administered intravenously to all patients. For 46 consecutive patients between January 1996 and July 2000, an antimicrobial agent was given 30 min before operation and thereafter every 12 h on the same day and the next 2 days after operation (the 3-day group). For 68 consecutive patients from August 2000 to October 2002, an antimicrobial agent was given once 30 min before operation and was additionally given only in the evening or night of the day of operation (the 1-day group). The incidence of SSI was retrospectively investigated. There were two patients who developed SSI in each group (4.3% in the 3-day group and 2.9% in the 1-day group). The incidence of SSI was not significantly different between the two groups. The 1-day protocol has efficacy equal to that of the 3-day protocol in prophylaxis of SSI. The 1-day use of a prophylactic antimicrobial agent may be recommended for the clean or clean-contaminated urologic laparoscopic surgery described above.

Aged↗

Idiopathic stuttering priapism: recovery of detumescence mechanism with temporal use of antiandrogen.

We report a case of idiopathic stuttering priapism in a 56-year-old Japanese man. We treated his recurrent priapism in stepwise fashion by withdrawal of the alpha/beta-blocker he used for hypertension, administration of low doses of an antiandrogen and baclofen, and finally by increasing the dose of antiandrogen, which lowered his testosterone to the castration level and was effective in preventing priapism. After 6 months of antiandrogen treatment, his erectile function gradually recovered to the baseline level, and he had no recurrence of priapism during the following 6 months without any medication.

Baclofen↗

Antiproliferative and antiangiogenic activities of genistein in human renal cell carcinoma.

OBJECTIVES: To determine whether genistein, an isoflavone that is plentiful in soy beans, could inhibit the growth of human renal cell carcinoma (RCC) cells in vitro, induce apoptosis, and suppress neovascularization in vivo induced by human RCC cells. METHODS: We investigated the effect of genistein on cell proliferation in four human RCC cell lines, SMKT R-1, R-2, R-3, and R-4. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling assay was performed to examine whether genistein could induce apoptosis in SMKT R-1 cells. To evaluate the effect of genistein on in vivo angiogenesis, we used a new mouse dorsal air sac model in which we could evaluate it simply and quantitatively. Radioisotope-labeled red blood cells were injected into a tail vein in mice bearing a Millipore filter chamber containing genistein, and the vascular volume was examined by measuring the radioactivity of the mouse dorsal skin. RESULTS: Treatment with genistein for 48 hours inhibited cell proliferation in a dose-dependent manner and 100 microg/mL genistein inhibited it in a time-dependent manner. A dose of 50 microg/mL genistein clearly induced cell apoptosis. The vascular volume after implantation of the Millipore filter chamber containing RCC cells increased to threefold that without RCC cells. Genistein in the Millipore filter chamber significantly decreased the neovascularization induced by human RCC cells in vivo. CONCLUSIONS: The results of this study demonstrated that genistein inhibited cell proliferation, induced apoptosis, and suppressed in vivo angiogenesis in human RCC cells. Genistein may be a promising antitumorigenic and antiangiogenic agent for the treatment and prevention of RCC.

Angiogenesis Inhibitors↗

Systemic inflammatory response syndrome in open versus laparoscopic adrenalectomy.

OBJECTIVES: To compare the surgical invasiveness of laparoscopic adrenalectomy with that of open surgery when the invasiveness is evaluated by the incidence of systemic inflammatory response syndrome (SIRS). METHODS: Patients who underwent open adrenalectomy (35 patients) and those who underwent transperitoneal laparoscopic adrenalectomy (35 patients) were included in this study. We retrospectively investigated the incidence and duration of SIRS in the two groups. Of the 70 patients, 39 had primary aldosteronism and 31 had clinically nonfunctioning adrenal tumors. RESULTS: The incidence of SIRS was 51.4% (18 patients) in the open group and 31.4% (11 patients) in the laparoscopic group (P = 0.14, Fisher's exact probability test). The mean duration of SIRS was 1.9 days in the open group and 1.2 days in the laparoscopic group (P = 0.04, unpaired t test). Surgical site infection, which occurred in 2 patients in the open group (5.7%) and 3 patients (8.5%) in the laparoscopic group, was the only infectious complication. No patient had any severe or life-threatening complications. CONCLUSIONS: Laparoscopic adrenalectomy seems less invasive than open surgery, when the magnitude of the invasiveness is evaluated by the incidence of SIRS.

Adrenal Gland Neoplasms↗

Local recurrence after radical cystectomy for invasive bladder cancer: an analysis of predictive factors.

OBJECTIVES: To examine which clinicopathologic parameters predict clinically detectable local recurrence after radical cystectomy. Local recurrence after radical cystectomy for invasive bladder cancer was infrequently observed until 20 years ago because of the lack of adequate diagnostic tools. The recent development and use of pelvic computed tomography has allowed us to detect local recurrence more precisely. However, only a few studies have investigated the rate and pattern of local recurrence in the computed tomography era. METHODS: This retrospective review included 145 patients with muscle-invasive bladder cancer treated with radical cystectomy, regional pelvic lymph node dissection, and urinary diversion between January 1990 and December 2001. The development of local recurrence and/or distant metastasis was analyzed as the endpoint using univariate and multivariate analyses. RESULTS: Local recurrence developed in 27 (18.6%) of the 145 patients at a median of 8 months after cystectomy. Of the 27 patients, 8 had local recurrence alone and 19 had concurrent distant metastasis. Distant metastasis without local recurrence developed in 34 patients (23.4%). Univariate and multivariate analyses revealed that Stage pT3-T4 and pathologic pelvic lymph node involvement were statistically significant factors predicting clinical failure, local recurrence, and/or distant metastasis. However, a concomitant squamous cell carcinoma component in the specimen was the only independent predictor of local recurrence alone in both univariate and multivariate analyses. CONCLUSIONS: Only the finding of a concomitant squamous cell carcinoma component in the specimen was an independent predictor of local recurrence in patients treated with radical cystectomy.

Adult↗

Radical cystectomy for invasive bladder cancer: results of multi-institutional pooled analysis.

BACKGROUND: We report the outcome of radical cystectomy for patients with invasive bladder cancer, who did not have regional lymph node or distant metastases, at 21 hospitals. METHODS: Retrospective, non-randomized, multi-institutional pooled data were analyzed to evaluate outcomes of patients who received radical cystectomy. Between 1991 and 1995, 518 patients with invasive bladder cancer were treated with radical cystectomy at 21 hospitals. Of these, 250 patients (48.3%) received some type of neoadjuvant and/or adjuvant therapy depending on the treatment policy of each hospital. RESULTS: The median follow-up period was 4.4 years, ranging from 0.1 to 11.4 years. The 5-year overall survival rate was 58% for all 518 patients. The 5-year overall survival rates for patients with clinical T2N0M0, T3N0M0 and T4N0M0 were 67%, 52% and 38%, respectively. The patients with pT1 or lower stage, pT2, pT3 and pT4 disease without lymph node metastasis had 5-year overall survivals of 81%, 74%, 47% and 38%, respectively. The patients who were node positive had the worst prognosis, with a 30% overall survival rate at 5 years. Neoadjuvant or adjuvant chemotherapy did not provide a significant survival advantage, although adjuvant chemotherapy improved the 5-year overall survival in patients with pathologically proven lymph node metastasis. CONCLUSIONS: The current retrospective study showed that radical cystectomy provided an overall survival equivalent to studies reported previously, but surgery alone had no more potential to prolong survival of patients with invasive cancer. Therefore, a large-scale randomized study on adjuvant treatment as well as development of new strategies will be needed to improve the outcome for patients with invasive bladder cancer.

Adult↗

Comparisons of percent equol producers between prostate cancer patients and controls: case-controlled studies of isoflavones in Japanese, Korean and American residents.

BACKGROUND: Our previous case-control study revealed that the Japanese residents in Japan could be divided into those who are able to degrade daidzein, a soybean isoflavone, to equol and those without this ability, and that the incidence of prostate cancer is higher in the latter group. METHODS: We recently conducted a similar case-control study involving not only Japanese residents in Japan but also Korean residents in Korea. The incidence of prostate cancer in Korean residents is known to be close to that of Japanese residents in Japan. On the other hand, American residents in the United States have a markedly higher incidence of prostate cancer as compared to Japanese residents in Japan. RESULTS: The number of subjects was 295 in Japan (133 patients and 162 controls), 122 in Korea (61 patients and 61 controls) and 45 in the United States (24 patients and 21 controls). The percentage of equol producers among patients and controls was 29% and 46% in Japan (P = 0.004) and 30% and 59% in Korea (P = 0.001), respectively. The active isoflavone level was markedly lower and the percentage of equol producers was also lower (17% for patients and 14% for controls) for Americans as compared to the Japanese and Koreans. CONCLUSIONS: These results suggest that the ability of producing equol or equol itself is closely related to the lower incidence of prostate cancer. The results also suggest that a diet based on soybean isoflavones will be useful in preventing prostate cancer.

Adult↗