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Featured researches published by Kazutoshi Okubo.


The Journal of Urology | 2002

THE NATURAL HISTORY OF SIMPLE RENAL CYSTS

Naoki Terada; Kentaro Ichioka; Yosuke Matsuta; Kazutoshi Okubo; Koji Yoshimura; Yoichi Arai

PURPOSE Although simple renal cysts are common in older patients, little is known concerning their natural history. We examined the natural history of renal cysts by investigating the prevalence and sequential changes in their size and number in individuals. MATERIALS AND METHODS We collected data on 14,314 individuals who participated in a multiphasic health screening program at our institute in 1999. An ultrasound renal cyst prevalence survey was performed. As a longitudinal study, 45 patients with renal cysts were followed a mean of 6 years from January 1993 to December 1999. RESULTS In the prevalence survey 1,700 individuals (11.9%) had at least 1 renal cyst on ultrasound. The ratio of men-to-women with cysts was 2:1. The prevalence of renal cysts increased more than 7-fold with age from 5.1% in the fourth to 36.1% in the eighth decade of life. Our longitudinal study revealed that the majority of cysts increased in size and number. The average increase in size and the rate of enlargement were 2.82 mm. and 6.3% yearly, respectively. Cysts in patients younger than 50 years grew more rapidly than those in patients 50 years old and older, at a rate of 3.94 and 1.84 mm. yearly, respectively (p = 0.010). Multiloculated cysts progressed more rapidly than simple cysts (6.93 versus 2.18 mm. yearly, p <0.0001). CONCLUSIONS The prevalence of renal cysts increases with age and shows a remarkable difference in incidence by sex. Renal cysts progress in size and number, and appear to grow more rapidly in younger patients. The natural history of multiloculated cysts may be distinct from that of simple cysts and warrants further investigation.


The Journal of Urology | 2001

Laparoscopic partial nephrectomy with a microwave tissue coagulator for small renal tumor.

Koji Yoshimura; Kazutoshi Okubo; Kentaro Ichioka; Naoki Terada; Yosuke Matsuta; Yoichi Arai

PURPOSE Laparoscopic partial nephrectomy is a challenging procedure due to the risk of excessive bleeding. We evaluated the usefulness of a microwave tissue coagulator during laparoscopic partial nephrectomy for small renal tumor. MATERIALS AND METHODS From January to July 2000, 6 patients with small renal tumors, from 11 to 25 mm. in diameter, underwent laparoscopic partial nephrectomy with a microwave tissue coagulator without renal pedicle clamping. There were 4 patients who underwent the transperitoneal and 2 who underwent the retroperitoneal approaches. RESULTS Mean operating time was 186 minutes (range 131 to 239), and blood loss was minimal. Complications were mild and tolerable, and there was no significant deterioration of renal function. CONCLUSIONS Laparoscopic partial nephrectomy with a microwave tissue coagulator is a useful and less invasive method for treatment of select small renal tumors. Long-term followup of patients is warranted to determine the potential for cancer control with this method.


The Journal of Urology | 2000

IMPACT OF INTERVENTIONAL THERAPY FOR BENIGN PROSTATIC HYPERPLASIA ON QUALITY OF LIFE AND SEXUAL FUNCTION: A PROSPECTIVE STUDY

Yoichi Arai; Yoshitaka Aoki; Kazutoshi Okubo; Hiroshi Maeda; Naoki Terada; Yosuke Matsuta; Shinya Maekawa; Keiji Ogura

PURPOSE Treatment for benign prostatic hyperplasia (BPH), including minimally invasive therapy, can impair the quality of life. We prospectively determined the impact of 4 different interventional therapies on quality of life and sexual function. MATERIALS AND METHODS A total of 173 patients were prospectively evaluated between February 1995 and August 1997. Treatment modalities consisted of standard transurethral resection of the prostate in 55 cases, transurethral microwave thermotherapy in 34, interstitial laser coagulation of the prostate in 42 and transurethral needle ablation in 42. Disease specific quality of life was assessed using the International Prostate Symptom Score quality of life assessment index and BPH impact index. In addition, a self-reporting questionnaire was completed before and 3 months after treatment to determine the impact on sexual function. RESULTS All 4 treatment groups showed significant improvement in the symptom score, International Prostate Symptom Score quality of life assessment score and BPH impact index score. Satisfaction with treatment was highest in patients treated with transurethral resection or laser coagulation. A mild to moderate decrease in erectile function was noted in 26.5%, 18.2%, 18.4% and 20.0% of the transurethral resection, microwave thermotherapy, laser coagulation and needle ablation groups, respectively, but there was no significant difference of mean pretreatment and posttreatment erectile function or libido scores in any group. Ejaculation loss or severe decrease in ejaculate volume was reported by 48.6%, 28.1%, 21.6% and 24.3% of the patients, respectively. Interestingly, 20 of the 44 patients (45. 5%) with loss of ejaculation or severe decrease in ejaculate reported deterioration of the sex life, while only 2 (3.6%) of the 56 without any change in ejaculate volume reported such deterioration. The association of ejaculatory dysfunction with an adverse impact on sexual activity was highly significant (p <0.0001). CONCLUSIONS Significant improvement in quality of life could be achieved with the present assessed interventional therapies. There was no significant change in sexual desire or erectile function with these therapies. Posttreatment sexual dysfunction appears to be mainly related to impaired ejaculatory function. Urologists should provide proper counseling regarding the possibility of this complication even in patients receiving minimally invasive treatment.


International Journal of Urology | 1999

Patient-reported quality of life after radical prostatectomy for prostate cancer

Yoichi Arai; Kazutoshi Okubo; Yoshitaka Aoki; Shinya Maekawa; Takashi Okada; Hiroshi Maeda; Osamu Ogawa; Tetsuro Kato

Background: Increasingly, quality of life (QOL) assessments are receiving greater attention in the management of malignancies, including prostate cancer. We evaluated the impact of radical prostatectomy on patient QOL 12 months or longer after surgery.


The Journal of Urology | 1997

Prostate specific antigen adjusted for the transition zone volume as an indicator of prostate cancer

Hiroshi Maeda; Yoichi Arai; Satoshi Ishitoya; Kazutoshi Okubo; Yoshitaka Aoki; Takashi Okada

PURPOSE We compared prostate specific antigen (PSA) adjusted for the transition zone volume with PSA and PSA density with regard to value in diagnosing prostate cancer in men with intermediate PSA levels of 4.1 to 10.0 ng./ml. in a community based urology practice. MATERIALS AND METHODS Between October 1994 and May 1996, PSA transition zone was obtained from 92 of 94 men who underwent systematic sextant biopsies and had a PSA value between 4.1 and 10.0 ng./ml. PSA transition zone, calculated by dividing the PSA value by the volume of the transition zone of the prostate, was compared with PSA and PSA density via the receiver operating characteristic (ROC) curves. RESULTS Of the 92 men 12 (13.0%) had prostate cancer. ROC curve analysis demonstrated that PSA transition zone and PSA density predicted the biopsy outcome significantly better than PSA (p <0.05 and p <0.01, respectively). In a subset of 59 men with normal digital rectal examination PSA transition zone predicted the biopsy outcome better than PSA density, although without significant difference. With a cutoff value of 0.3 PSA transition zone had a sensitivity of 75% and a specificity of 54%. CONCLUSIONS PSA transition zone is more specific than PSA in distinguishing benign from malignant disease in men with intermediate PSA levels of 4.1 to 10.0 ng./ml., especially in those with normal digital rectal examination. Further study is necessary to discuss whether PSA transition zone is superior to PSA density.


Urology | 1999

Complexed prostate-specific antigen and its volume indexes in the detection of prostate cancer

Hiroshi Maeda; Yoichi Arai; Yoshitaka Aoki; Kazutoshi Okubo; Takashi Okada; Shinya Maekawa

OBJECTIVES To evaluate complexed prostate-specific antigen (cPSA), cPSA density (cPSAD), and cPSA adjusted for the transition zone volume (cPSA-TZ) in comparison with the free-to-total PSA ratio (F/T PSA) and free-to-complexed PSA ratio (F/C PSA) as a means of diagnosing prostate cancer. METHODS Transition zone volume was determined in 137 of 142 men who underwent systematic sextant biopsies and had total PSA (tPSA) values between 4.1 and 10.0 ng/mL. cPSAD and cPSA-TZ were calculated by dividing the cPSA value by the whole prostate volume and the transition zone volume, respectively. RESULTS Of the 137 men, 23 (16.8%) had prostate cancer. cPSA predicted the biopsy outcome better than tPSA, F/T PSA, or F/C PSA, although the difference was not significant. A cutoff value of 4.1 ng/mL for cPSA provided a specificity of 42% and a sensitivity of 87%. A combination of cPSA and F/C PSA maintained a sensitivity of 83% and gave an increased specificity of 54%. In a subgroup of 65 patients with smaller prostate volumes (less than 45 mL), the diagnostic value of cPSA-TZ was remarkably increased. A cutoff value of 0.31 for cPSA-TZ provided a sensitivity of 93% and a high specificity of 72%. CONCLUSIONS cPSA was more specific than tPSA and F/T PSA. As a component of F/C PSA, free PSA could provide additional value to cPSA. cPSA-TZ and cPSAD could be better indicators for prostate cancer than cPSA.


International Journal of Urology | 2010

Outcome of different post-orchiectomy management for stage I seminoma: Japanese multi-institutional study including 425 patients

Tomomi Kamba; Toshiyuki Kamoto; Kazutoshi Okubo; Satoshi Teramukai; Yoshiyuki Kakehi; Osamu Ogawa

Objectives:  To clarify the contemporary clinical outcome of stage I seminoma and to provide information on treatment options to patients.


International Journal of Urology | 2002

Symptom-specific quality of life in patients with benign prostatic hyperplasia.

Koji Yoshimura; Yoichi Arai; Kentaro Ichioka; Naoki Terada; Yosuke Matsuta; Kazutoshi Okubo

Abstract Background: We investigated which factors are most bothersome to preoperative patients with benign prostatic hyperplasia (BPH).


The Journal of Urology | 2001

Tubeless cutaneous ureterostomy: the Toyoda method revisited.

Koji Yoshimura; Shinya Maekawa; Kentaro Ichioka; Naoki Terada; Yosuke Matsuta; Kazutoshi Okubo; Yoichi Arai

PURPOSE Cutaneous ureterostomy is a less invasive method of urinary diversion and an attractive option especially in patients at high risk. We retrospectively examined the long-term outcome of the method introduced by Toyoda. MATERIALS AND METHODS Since 1983 the Toyoda cutaneous ureterostomy has been performed in 61 patients (103 renal units) with a minimum of 3 months of followup. The ureteral patency rate was reviewed. RESULTS Of the 92 renal units (89%) that achieved a tubeless condition 53 (51%) had no hydronephrosis, 23 (22%) had mild to moderate hydronephrosis without the need for treatment, 14 (14%) were not evaluated during followup and 2 (2%) were removed due to subsequent renal pelvic and/or ureteral carcinoma. CONCLUSIONS A high ureteral patency rate was achieved with the Toyoda cutaneous ureterostomy. This procedure is a reasonable alternative to other forms of urinary diversion.


International Journal of Urology | 2001

Acute normovolemic hemodilution for radical prostatectomy: Can it replace preoperative autologous blood transfusion?

Naoki Terada; Yoichi Arai; Yosuke Matsuta; Shinya Maekawa; Kazutoshi Okubo; Keiji Ogura; Norimasa Matsuda; Akitomo Yonei

Abstract Background: Although preoperative autologous blood donation (PAD) is accepted as a standard of care for radical prostatectomy, it is costly, time‐consuming and has risks associated with blood storage. Acute normovolemic hemodilution (ANH) is reported to be less expensive and to preserve blood components more effectively than PAD. In the present study, the efficacy and safety of these two autologous blood‐collection techniques were compared.

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