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Dive into the research topics where Samuel K. Park is active.

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Featured researches published by Samuel K. Park.


European Urology | 2012

Radiofrequency Ablation Versus Partial Nephrectomy in Patients with Solitary Clinical T1a Renal Cell Carcinoma: Comparable Oncologic Outcomes at a Minimum of 5 Years of Follow-Up

Ephrem O. Olweny; Samuel K. Park; Yung K. Tan; Sara L. Best; Clayton Trimmer; Jeffrey A. Cadeddu

BACKGROUND Long-term comparative outcomes for radiofrequency ablation (RFA) versus partial nephrectomy (PN) for the primary treatment of clinical T1a renal cell carcinoma (RCC) have not previously been reported. OBJECTIVE Report comparative 5-yr oncologic outcomes for RFA versus PN in patients with clinical T1a RCC. DESIGN, SETTING, AND PARTICIPANTS Observational single-institution cohort study, involving consecutive patients with a solitary histologically confirmed T1a RCC treated by RFA or PN and followed for a minimum of 5 yr. Those presenting with synchronous multiple, metachronous, bilateral, and/or metastatic disease, a history of hereditary RCC syndromes, a family history of RCC, and with post-treatment follow-up <5 yr were excluded from analysis. MEASUREMENTS The Kaplan-Meier method was used to determine 5-yr overall survival (OS), cancer-specific survival (CSS), local recurrence-free survival (local RFS), overall disease-free survival (DFS), and metastasis-free survival (MFS) for RFA versus PN. Survival curves were compared using the log-rank test. A p value ≤ 0.05 was considered statistically significant. RESULTS AND LIMITATIONS A total of 37 patients in each group met the selection criteria. The RFA cohort was significantly older and had more advanced comorbidities, but other patient characteristics were similar. For RFA versus PN, median follow-up was 6.5 yr (interquartile range [IQR]: 5.8-7.1) versus 6.1 yr (IQR: 5.4-7.3) (p = 0.68), respectively. The 5-yr OS was 97.2% versus 100% (p = 0.31), CSS was 97.2% versus 100% (p = 0.31), DFS was 89.2% versus 89.2% (p = 0.78), local RFS was 91.7% versus 94.6% (p = 0.96), and MFS was 97.2% versus 91.8% (p = 0.35), respectively. Study limitations are retrospective data analysis, loss to follow-up, limited statistical power, and limited generalizability of our data. CONCLUSIONS In appropriately selected patients, RFA is an effective minimally invasive therapy for the treatment of cT1a RCC, yielding comparable long-term oncologic outcomes to nephron-sparing surgery.


The Journal of Urology | 2012

Long-Term Outcomes of Renal Tumor Radio Frequency Ablation Stratified by Tumor Diameter: Size Matters

Sara L. Best; Samuel K. Park; Ramy F. Yaacoub; Ephrem O. Olweny; Yung K. Tan; Clayton Trimmer; Jeffrey A. Cadeddu

PURPOSE Renal tumor size influences the efficacy of radio frequency ablation but identification of confident size cutoffs has been limited by small numbers and short followup. We evaluated tumor size related outcomes after radio frequency ablation for patients with adequate (greater than 3 years) followup. MATERIALS AND METHODS We identified 159 tumors treated with radio frequency ablation as primary treatment. Disease-free survival was defined as the time from definitive treatment to local recurrence, detection of metastasis or the most recent imaging showing no evidence of disease. Patients were evaluated with contrast enhancing imaging preoperatively, and at 6 weeks, 6 months and at least annually thereafter. RESULTS Median tumor size was 2.4 cm (range 0.9 to 5.4) with a median followup of 54 months (range 1.5 to 120). Renal cell carcinoma was confirmed in 72% of the 150 tumors that had pre-ablation biopsy (94%). The 3 and 5-year disease-free survival was comparable at 92% and 91% overall, and was dependent on tumor size, being 96% and 95% for tumors smaller than 3.0 cm and 79% and 79%, respectively, for tumors 3 cm or larger (p=0.001). Most failures (14 of 18) were local, either incomplete ablations or local recurrences. This is an intent to treat analysis and, therefore, includes patients ultimately found to have benign tumors, although outcomes were comparable in patients with cancer. CONCLUSIONS Radio frequency ablation treatment success of the small renal mass is strongly correlated with tumor size. Radio frequency ablation provides excellent and durable outcomes, particularly in tumors smaller than 3 cm. Of tumors 3 cm or larger, approximately 20% will recur such that alternative treatment techniques should be considered. However, most treatment failures are local and are often successfully treated with another ablation session.


European Urology | 2011

Patient-reported body image and cosmesis outcomes following kidney surgery: Comparison of laparoendoscopic single-site, laparoscopic, and open surgery

Samuel K. Park; Ephrem O. Olweny; Sara L. Best; Chad R. Tracy; Saad A. Mir; Jeffrey A. Cadeddu

BACKGROUND Laparoendoscopic single-site surgery (LESS) is reported to result in superior cosmesis versus alternative surgical approaches, based solely on surgeon assessment or anecdotal evidence. OBJECTIVE Evaluate patient-reported body image and cosmesis outcomes following kidney surgery. DESIGN, SETTING, AND PARTICIPANTS We conducted a prospective and retrospective observational cohort study involving patients who underwent kidney surgery (n=114) via LESS (n=35), laparoscopic (n=52), or open (n=27) approaches. Cosmesis was evaluated using a comprehensive survey administered ≥3 mo postoperatively. MEASUREMENTS Survey components were a body image questionnaire (BIQ) consisting of body image and cosmesis subscales, a photo-series questionnaire (PSQ) assessing scar preferences after knowledge of scar outcomes for alternative surgical approaches, and query of preference for future surgical approach using a trade-off method. Body image, cosmesis, and PSQ scales ranged from 5 to 20, 3 to 24, and 1 to 10, respectively. RESULTS AND LIMITATIONS Median BIQ component scores did not significantly differ across surgical approaches. Median ratings for the LESS, laparoscopy, and open scar photographs were 8, 5, and 5, respectively (p=0.0001). Before viewing photographs, median self-scar ratings for LESS, laparoscopy, and open approaches were 9, 5, and 6.5, respectively (p=0.02); after photographs, ratings were 9, 7, and 7, respectively (p=0.008). Assuming equivalent surgical risk among the approaches, overall preference for future LESS, laparoscopy, or open surgery was 39%, 33%, or 4%, respectively. As theoretical risk of LESS was raised, preference for LESS decreased, whereas preference for laparoscopy and open surgery increased. Study limitations are a nonrandomized design and the use of a nonvalidated scale. CONCLUSIONS Urologic patients favor LESS cosmesis outcomes over those for laparoscopy or open surgery. Considering the superior scar satisfaction among LESS patients, who were younger and more likely to be undergoing surgery for benign disease, we infer that this demographic most values the cosmetic advantages of LESS.


European Urology | 2012

Perioperative Comparison of Robotic Assisted Laparoendoscopic Single-Site (LESS) Pyeloplasty Versus Conventional LESS Pyeloplasty

Ephrem O. Olweny; Samuel K. Park; Yung K. Tan; Cenk Gurbuz; Jeffrey A. Cadeddu; Sara L. Best

BACKGROUND Conventional laparoendoscopic single-site (C-LESS) pyeloplasty is technically challenging due to instrument clashing, loss of triangulation, and difficulty sewing. Application of the da Vinci S or Si robotic platforms could potentially overcome these challenges. OBJECTIVE Compare our initial experience with robotic assisted laparoendoscopic single-site (R-LESS) pyeloplasty to our latter experience with C-LESS pyeloplasty (ie, after the initial 15 patients). DESIGN, SETTING, AND PARTICIPANTS This single-institution retrospective observational cohort study involved consecutive patients who presented with symptomatic ureteropelvic junction obstruction and who were deemed suitable for single-incision pyeloplasty by the treating surgeon. MEASUREMENTS Demographic, clinical, perioperative, and early postoperative comparative outcomes. RESULTS AND LIMITATIONS Ten patients each underwent R-LESS or C-LESS pyeloplasty by a single surgeon between March 2009 and July 2011. For R-LESS and C-LESS groups, age, gender distribution, body mass index, proportion of patients with prior abdominal surgery, estimated blood loss, and hospital length of stay were statistically similar. Mean operative time was significantly longer for R-LESS (226 vs 188 min; p=0.007). C-LESS pyeloplasty alone required an accessory port for the anastomosis in 10 of 10 cases. Two conversions to standard laparoscopy and two postoperative complications occurred in 3 of 10 patients in the C-LESS group, compared with no conversions and one postoperative complication in the R-LESS group (p=0.26). Study limitations are a retrospective design, a modest number of patients, and a lack of quantification of subjective outcomes such as instrument clashing and maneuverability. CONCLUSIONS Adaptation of the da Vinci Si robotic surgical platform to laparoendoscopic single-site pyeloplasty appears to reduce the physical learning curve for this complex procedure. Future prospective, comprehensive evaluation of additional outcomes including subjective parameters, cosmesis, and longer term functional outcomes will help better define its role in minimally invasive dismembered pyeloplasty and better estimate its associated learning curve.


BJUI | 2012

Importance of cosmesis to patients undergoing renal surgery: a comparison of laparoendoscopic single-site (LESS), laparoscopic and open surgery

Ephrem O. Olweny; Saad A. Mir; Sara L. Best; Samuel K. Park; Chester J. Donnally; Jeffrey A. Cadeddu; Chad R. Tracy

Study Type – Therapy (case series)


BJUI | 2012

Self-retaining barbed suture for parenchymal repair during laparoscopic partial nephrectomy; Initial clinical experience

Ephrem O. Olweny; Samuel K. Park; Casey A. Seideman; Sara L. Best; Jeffrey A. Cadeddu

Study Type – Therapy (case series)


Journal of Endourology | 2012

Robot-assisted laparoendoscopic single-site pyeloplasty: technique using the da Vinci Si robotic platform.

Casey A. Seideman; Yung K. Tan; Stephen Faddegon; Samuel K. Park; Sara L. Best; Jeffrey A. Cadeddu; Ephrem O. Olweny

Conventional laparoscopic dismembered pyeloplasty (LP) is an established alternative to open pyeloplasty given equivalent intermediate-term outcomes and decreased morbidity. Laparoendoscopic single-site (LESS) pyeloplasty has the potential to further decrease the morbidity of LP, while yielding superior cosmesis. It is, however, technically very challenging even with the use of an accessory port, largely because of the difficulty of intracorporeal suturing through a single umbilical incision. Application of the da Vinci robotic surgical platform to LESS pyeloplasty (R-LESS) has the potential to overcome these limitations. We describe our technique for R-LESS pyeloplasty using the da Vinci Si robot. We have found that use of the robotic system in conjunction with certain technique modifications helps to reduce the technical difficulty of LESS pyeloplasty and to shorten the physical learning curve associated with the procedure.


Jsls-journal of The Society of Laparoendoscopic Surgeons | 2012

Laparoendoscopic single-site (LESS) pyeloplasty for horseshoe ureteropelvic junction obstruction.

Stephen Faddegon; Yung K. Tan; Ephrem O. Olweny; Samuel K. Park; Sara L. Best; Jeffrey A. Cadeddu

This report suggests that laparoscopic single-site pyeloplasty of uteropelvic junction obstruction associated with horseshoe kidney is feasible, safe, and effective in select patients.


Emerging Digital Micromirror Device Based Systems and Applications IV | 2012

Evaluation of a novel laparoscopic camera for characterization of renal ischemia in a porcine model using digital light processing (DLP) hyperspectral imaging

Ephrem O. Olweny; Yung K. Tan; Stephen Faddegon; Neil Jackson; Eleanor Wehner; Sara L. Best; Samuel K. Park; Abhas Thapa; Jeffrey A. Cadeddu; Karel J. Zuzak

Digital light processing hyperspectral imaging (DLP® HSI) was adapted for use during laparoscopic surgery by coupling a conventional laparoscopic light guide with a DLP-based Agile Light source (OL 490, Optronic Laboratories, Orlando, FL), incorporating a 0° laparoscope, and a customized digital CCD camera (DVC, Austin, TX). The system was used to characterize renal ischemia in a porcine model.


Canadian Journal of Urology | 2013

A comparison of long term renal functional outcomes following partial nephrectomy and radiofrequency ablation.

Stephen Faddegon; Tom Ju; Ephrem O. Olweny; Zhuowei Liu; Woong Kyu Han; Gang Yin; Yung K. Tan; Jeffrey Gahan; Selahattin Bedir; Yun Bo Ma; Samuel K. Park; Ganesh V. Raj; Jeffrey A. Cadeddu

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Ephrem O. Olweny

University of Texas Southwestern Medical Center

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Jeffrey A. Cadeddu

University of Texas Southwestern Medical Center

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Sara L. Best

University of Texas Southwestern Medical Center

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Yung K. Tan

University of Texas Southwestern Medical Center

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Stephen Faddegon

University of Texas Southwestern Medical Center

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Saad A. Mir

University of Texas Southwestern Medical Center

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Casey A. Seideman

University of Texas Southwestern Medical Center

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Cenk Gurbuz

University of Texas Southwestern Medical Center

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Clayton Trimmer

University of Texas Southwestern Medical Center

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