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Dive into the research topics where Stephen A. Poon is active.

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Featured researches published by Stephen A. Poon.


The Journal of Urology | 2008

Laparoscopic Lymphatic Sparing Varicocelectomy in Adolescents

Kenneth I. Glassberg; Stephen A. Poon; Carl K. Gjertson; G. Joel DeCastro; Rosalia Misseri

PURPOSE Laparoscopic varicocelectomy is similar to an open Palomo repair. Both procedures involve en masse ligation of the internal spermatic cord, and both are associated with a 1% to 3% incidence of recurrence and up to a 30% incidence of hydroceles. We sought to determine the impact of lymphatic preservation on hydrocele formation and the success of varicocelectomy. MATERIALS AND METHODS We retrospectively evaluated 191 patients with a mean age of 15.2 years who underwent laparoscopic varicocelectomy and at least 6 months of followup. Patients were divided into 2 groups-those who had undergone a lymphatic sparing procedure and those who had undergone a nonlymphatic sparing technique. The incidence of recurrence/persistence, postoperative hydrocele formation and postoperative hydrocele requiring surgery or aspiration was analyzed. RESULTS A total of 174 laparoscopic lymphatic sparing procedures (132 patients, 42 bilateral) and 88 nonlymphatic sparing repairs (59 patients, 29 bilateral) were performed, with a mean followup of 26.1 months. Lymphatic sparing surgery was associated with a decreased incidence of postoperative hydrocele (3.4% vs 11.4%, p = 0.025). There was no significant difference in incidence of persistent or recurrent varicocele requiring reoperation following lymphatic sparing (5 sides, 2.9%) vs nonlymphatic sparing (4 sides, 4.5%) varicocelectomy (p = 0.736). CONCLUSIONS Laparoscopic lymphatic sparing varicocelectomy is preferable to an open or laparoscopic Palomo repair that does not preserve the lymphatics. It has a significantly lower incidence of postoperative hydroceles, especially those requiring surgical intervention, and still maintains a low incidence of persistence/recurrence. The procedure is especially advantageous for bilateral varicocelectomy.


The Journal of Urology | 2009

Peak Retrograde Flow: A Novel Predictor of Persistent, Progressive and New Onset Asymmetry in Adolescent Varicocele

Kristin A. Kozakowski; Carl K. Gjertson; G. Joel DeCastro; Stephen A. Poon; Anthony Gasalberti; Kenneth I. Glassberg

PURPOSE The major indication for adolescent left varicocelectomy is testicular asymmetry. However, a period of observation is often recommended preoperatively to determine if the asymmetry resolves, persists or progresses. We investigated whether varicocele grade or the duplex Doppler ultrasound measurements of peak retrograde flow and mean vein diameter could be used as predictors of persistent, progressive or new onset asymmetry. MATERIALS AND METHODS Only patients with left varicoceles who had undergone at least 2 duplex Doppler ultrasounds without intervening surgery were included in the study. Grade of varicocele, peak retrograde flow and mean vein diameter were analyzed as possible determinants of catch-up growth, or persistent or new onset asymmetry. RESULTS A total of 77 patients (mean age 14.3 years, range 9 to 20) were identified with a mean observation period of 13.2 months. Of the patients 50 (65%) had 10% or greater asymmetry at the first measurement. Of patients with initial 20% or greater asymmetry 71% had persistent or worsening asymmetry on followup evaluation. All 14 patients with the combination of an initial peak retrograde flow 38 cm per second or greater and 20% or greater asymmetry had progressive asymmetry on followup examination. Peak retrograde flow was the only significant parameter of predictive value for persistent or worsening asymmetry (p = 0.032). CONCLUSIONS Peak retrograde flow can serve as a valuable tool in predicting persistent, progressive and new onset asymmetry. Varicoceles associated with a peak retrograde flow of 38 cm per second or greater and 20% or greater asymmetry should be considered for varicocelectomy at initial presentation. Patients with peak retrograde flow greater than 30 cm per second need to be monitored carefully. Those with peak retrograde flow less than 30 cm per second are less likely to require surgery.


The Journal of Urology | 2013

Trends in Partial and Radical Nephrectomy: An Analysis of Case Logs from Certifying Urologists

Stephen A. Poon; Jonathan L. Silberstein; Ling Chen; Behfar Ehdaie; Philip H. Kim; Paul Russo

PURPOSE Surgical treatment options for renal masses include radical vs partial nephrectomy and the open vs laparoscopic approach. Using American Board of Urology (ABU) case log data, we investigated contemporary trends in these treatment options, and how surgeon and practice characteristics may influence these trends. MATERIALS AND METHODS Annualized case log data for nephrectomy were obtained from the ABU for all urologists certifying or recertifying from 2002 to 2010. We evaluated trends in nephrectomy use. Logistic regression was used to evaluate surgeon and practice characteristics as predictors of partial and laparoscopic procedures. RESULTS From the 3,852 case logs submitted by nonpediatric urologists we analyzed a total of 48,384 nephrectomies. From 2002 to 2010 the proportion of annual nephrectomies performed as open radical nephrectomy gradually decreased from 54% to 29%. During the same period, there was a moderate gradual increase in laparoscopic radical nephrectomies (from 30% to 39%). The proportion of open partial nephrectomies remained stable at 15%, while laparoscopic partial nephrectomy increased from 2% to 17%. On multivariable analysis the use of partial nephrectomy and laparoscopy was predicted by urologist annual nephrectomy volume, initial or recertification status, subspecialty, practice area size and geographic region. CONCLUSIONS Since 2002, the use of laparoscopic nephrectomy and partial nephrectomy has increased. However, the diffusion of these techniques is not uniform. Initial certification, higher surgical volume, and practicing in areas with more than 1,000,000 population and in the Northeast region were associated with greater use of laparoscopy and partial nephrectomy. Factors that affect the adoption of these techniques require further research.


The Journal of Urology | 2009

Adolescent varicocelectomy--is the potential for catch-up growth related to age and/or Tanner stage?

G. Joel DeCastro; Ahmad Shabsigh; Stephen A. Poon; Laurent Laor; Kenneth I. Glassberg

PURPOSE Adolescent varicocelectomy is associated with a 70% incidence of postoperative catch-up growth in boys with ipsilateral testicular hypotrophy. We determined whether preoperative patient age and Tanner stage were related to subsequent catch-up growth. In other words if patients are followed with a period of observation, will a window of opportunity be lost for achieving catch-up growth? MATERIALS AND METHODS We studied a total of 163 boys (mean age 15.1 years, range 10 to 24) with left or bilateral varicoceles who demonstrated 10% asymmetry or greater preoperatively, and had preoperative and postoperative testicular volume measurements available (using either ring orchidometer or ultrasound). Of these patients 59 also had preoperative Tanner stage recorded. RESULTS Of the patients with preoperative left hypotrophy 69% had achieved catch-up growth at last followup (mean followup 28 months). When treated as a continuous variable, or when divided into general prepubertal vs postpubertal groupings, age at surgery was not significantly associated with catch-up growth. Similarly, there was no significant difference in catch-up growth associated with grade of varicocele, duration of postoperative followup or presence of unilateral left vs bilateral varicocele. No association with Tanner stage was found, although the patient numbers were too small to draw any statistically significant conclusions. CONCLUSIONS The prevalence of testicular catch-up growth after varicocelectomy is high, even for patients in their early 20s. Among males 10 to 24 years old there is no specific age or Tanner stage that offers the best opportunity for catch-up growth.


The Journal of Urology | 2011

Comparative Outcomes of Pure Squamous Cell Carcinoma and Urothelial Carcinoma With Squamous Differentiation in Patients Treated With Radical Cystectomy

Behfar Ehdaie; Alexandra C. Maschino; Shahrokh F. Shariat; Jorge Rioja; Robert J. Hamilton; William T. Lowrance; Stephen A. Poon; Hikmat Al-Ahmadie; Harry W. Herr

PURPOSE We compared clinical outcomes, and identified predictors of cancer specific and overall survival after radical cystectomy in patients with urothelial carcinoma with squamous differentiation and those with pure squamous cell carcinoma. MATERIALS AND METHODS We reviewed data on 2,031 patients treated with radical cystectomy and pelvic lymph node dissection at a single high volume referral center. Of these patients 78 had squamous cell carcinoma and 67 had squamous differentiation. Survival estimates by histological subtype were described using Kaplan-Meier methods. Within histological subtypes pathological stage, nodal invasion, soft tissue margins, age and gender were evaluated as predictors of cancer specific survival and overall survival using univariate Cox regression. RESULTS Median followup was 44 months. Of 104 patient deaths 60 died of their disease. We did not find a statistically significant difference between survival curves of patients with squamous cell carcinoma and squamous differentiation (log rank overall survival p = 0.6, cancer specific survival p = 0.17). Positive soft tissue margins were associated with worse cancer specific survival (HR 6.92, 95% CI 2.98-16.10, p ≤0.0005) and overall survival (HR 3.68, 95% CI 1.84-7.35, p ≤0.0005) in patients with pure squamous cell carcinoma. Among patients with squamous differentiation, pelvic lymphadenopathy was associated with decreased overall survival (HR 2.52, 95% CI 1.33-4.77, p = 0.004) and cancer specific survival (HR 3.23, 95% CI 1.57-6.67, p = 0.002). CONCLUSIONS There appears to be no evidence of a difference in cancer specific survival or overall survival between patients with squamous cell carcinoma and those with squamous differentiation treated with radical cystectomy and pelvic lymph node dissection. Patients with squamous differentiation and tumor metastases to pelvic lymph nodes should be followed more closely, and adjuvant treatment should be considered to improve survival. Wide surgical resection is critical to achieve local tumor control and improve survival in patients with squamous cell carcinoma.


The Journal of Urology | 2010

Testicular Asymmetry and Adolescent Varicoceles Managed Expectantly

Stephen A. Poon; Carl K. Gjertson; Miguel A. Mercado; Peter M. Raimondi; Kristin A. Kozakowski; Kenneth I. Glassberg

PURPOSE Adolescent varicocele is often associated with testicular asymmetry. Depending on the degree of asymmetry, some physicians will recommend surgery. However, given the possibility that asynchronous growth may be transient, others advocate for a period of observation. We reviewed our outcomes in such patients who were initially treated expectantly. MATERIALS AND METHODS We retrospectively reviewed our pediatric varicocele database. We analyzed the outcomes of patients presenting for evaluation of varicocele who were followed with serial testicular volume measurements using scrotal ultrasound or ring orchidometry and who had at least a 6-month interval between measurements. Fishers exact test was used to compare groups based on initial and final testicular asymmetry. RESULTS We identified 181 patients (median age 13.8 years) who were followed expectantly. Serial volume measurements had been obtained at a median interval of 12 months (interquartile range 8 to 21) between first and most recent visits. Mean percent asymmetry for the group did not change with time. Among patients who initially had less than 20% asymmetry 35% had 20% or greater asymmetry on followup, and among those with 20% or greater asymmetry initially 53% remained in that range (p = 0.007). CONCLUSIONS Asymmetry can be a transient phenomenon. Patients with initial asymmetry can end up with significant asymmetry, and many with significant asymmetry can have catch-up growth. However, when patients have a peak retrograde flow of 38 cm per second or greater on duplex Doppler ultrasound in association with 20% or greater asymmetry spontaneous catch-up growth is unlikely to occur.


The Journal of Urology | 2010

Adolescent Varicocele: Influence of Tanner Stage at Presentation on the Presence, Development, Worsening and/or Improvement of Testicular Hypotrophy Without Surgical Intervention

Jason P. Van Batavia; Solomon Woldu; Peter M. Raimondi; Benjamin A. Spencer; Beverly J. Insel; Stephen A. Poon; Kenneth I. Glassberg

PURPOSE Testicular asymmetry in adolescents with varicocele can worsen, remain unchanged or decrease on followup. We determined the incidence of testicular asymmetry at presentation by Tanner stage and the correlation between Tanner stage at presentation and subsequent changes in percent asymmetry (ability for catch-up growth or progressive asymmetry) without surgical intervention. MATERIALS AND METHODS We retrospectively studied the records of 115 boys with a mean age of 14.1 years (range 9.2 to 20.0) with grade 2 or 3 left varicocele who underwent testicular volume measurement at 2 visits at least that were a minimum of 6 months apart. Of the patients 92% and 8% underwent Doppler duplex ultrasound and orchidometry, respectively. Patients were divided into 2 groups, including those with less than 15% and those with 15% or greater asymmetry. Catch-up growth was defined as less than 15% asymmetry at any subsequent visit. RESULTS At presentation 58%, 64%, 67%, 35% and 39% of Tanner 1 to 5 cases showed 15% or greater testicular asymmetry, respectively. When Tanner 1 to 3 cases were combined and compared with Tanner 4 and 5 cases, the difference in initial asymmetry was significant (64% vs 38%, p = 0.007). Although it was not statistically significant, there was a trend toward more catch-up growth for the later Tanner stages, including 27% for Tanner 1 to 3 vs 53% for Tanner 4 and 5 (p = 0.06). CONCLUSIONS Slightly more than 50% of children and adolescents referred with varicocele have 15% or greater testicular asymmetry at presentation. Initial asymmetry is statistically more common in cases of earlier Tanner stages (1 to 3). Adolescents with 15% or greater testicular asymmetry who present at higher Tanner stages (4 and 5) show a trend toward a higher incidence of catch-up growth, although it is not significant.


Journal of Pediatric Urology | 2009

Adolescent varicocelectomy: Postoperative catch-up growth is not secondary to lymphatic ligation

Stephen A. Poon; Kristin A. Kozakowski; G. Joel DeCastro; Carl K. Gjertson; Kenneth I. Glassberg

PURPOSE The major indication for adolescent varicocelectomy is testicular asymmetry with the left testicle smaller than the right. Catch-up growth following surgery is one of the parameters used to assess efficacy of surgery. However, it is not clear whether this represents true tissue growth or increased interstitial fluid secondary to lymphatic obstruction. The purpose of this study was to compare catch-up growth in patients who underwent varicocelectomy with and without lymphatic preservation. MATERIALS AND METHODS We retrospectively analyzed the outcomes of 136 boys (mean age 15.1years) who had 10% or greater preoperative testicular asymmetry and underwent varicocelectomy between 1997 and 2006. Surgery was either a laparoscopic nonlymphatic sparing or laparoscopic lymphatic sparing varicocelectomy. All patients had pre- and postoperative ultrasound volume measurements at least 6months following surgery. The groups were compared for incidence of postoperative catch-up growth, achieving less than 10% testicular asymmetry. RESULTS After a mean follow up of 24.7months, catch-up growth was achieved in 62.8% of patients. There was no significant difference between the groups in regard to catch-up growth (51.7% vs 66.3%, P=0.193). CONCLUSIONS Since no significant difference was found between the laparoscopic nonlymphatic sparing and laparoscopic lymphatic sparing varicocelectomies, we conclude that lymphatic obstruction is not the cause of catch-up growth.


The Journal of Urology | 2012

Surgical Practice Patterns for Male Urinary Incontinence: Analysis of Case Logs from Certifying American Urologists

Stephen A. Poon; Jonathan L. Silberstein; Caroline Savage; Alexandra C. Maschino; William T. Lowrance; Jaspreet S. Sandhu

PURPOSE Several options exist for the surgical correction of male stress urinary incontinence including periurethral bulking agents, artificial urinary sphincters and the recently introduced male urethral slings. We investigated contemporary trends in the use of these treatments. MATERIALS AND METHODS Annualized case log data for incontinence surgeries from certifying and recertifying urologists were obtained from the ABU (American Board of Urology), ranging from 2004 to 2010. Chi-square tests and logistic regression models were used to evaluate the association between surgeon characteristics (type of certification, annual volume, practice type and practice location) and the use of incontinence procedures. RESULTS Among the 2,036 nonpediatric case logs examined the number of incontinence treatments reported for certification has steadily increased over time from 1,936 to 3,366 treatments per year from 2004 to 2010 (p = 0.008). Nearly a fifth of urologists reported placing at least 1 sling. The proportion of endoscopic procedures decreased from 80% of all incontinence procedures in 2004 to 60% in 2010, but they remained the exclusive incontinence procedure performed by 49% of urologists. A urologists increased use of endoscopic treatments was associated with a decreased likelihood of performing a sling procedure (OR 0.5, p <0.0005). Artificial urinary sphincter use remained stable, accounting for 12% of procedures. CONCLUSIONS Incontinence procedures are on the rise. Urethral slings have been widely adopted and account for the largest increase among treatment modalities. Endoscopic treatments continue to be commonly performed and may represent overuse in the face of improved techniques. Further research is required to validate these trends.


BJUI | 2009

Invasion of renal sinus fat is not an independent predictor of survival in pT3a renal cell carcinoma

Stephen A. Poon; Joshua Gonzalez; Mitchell C. Benson; James M. McKiernan

To clarify the significance of the location of extrarenal tumour extension of renal cell carcinoma (RCC) as in the 2002 Tumour‐Nodes‐Metastasis classification. Renal cortical tumours with perirenal fat invasion (PFI) or sinus fat invasion (SFI) are consolidated within the pT3a grouping; tumours with SFI are close to the renal veins, lymphatics and the collecting system. This might carry a worse prognosis for disease‐specific survival (DSS), but reports are limited and contradictory.

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Carl K. Gjertson

University of Connecticut Health Center

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G. Joel DeCastro

Columbia University Medical Center

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Mitchell C. Benson

Johns Hopkins University School of Medicine

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James M. McKiernan

Columbia University Medical Center

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Miguel A. Mercado

Baylor College of Medicine

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Paul Russo

Memorial Sloan Kettering Cancer Center

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