World J Urol (2008) 26:91–95 DOI 10.1007/s00345-007-0217-0
O R I G I N A L A R T I CL E
Impact of body mass index on outcomes after robot assisted radical prostatectomy Erik P. Castle · Fatih Atug · Michael Woods · Raju Thomas · Rodney Davis
Received: 12 July 2007 / Accepted: 22 September 2007 / Published online: 17 October 2007 © Springer-Verlag 2007
Abstract In this study we evaluated the impact of body mass index (BMI) on operative and perioperative parameters and surgical margin rates, in patients who underwent robotic assisted radical prostatectomy (RARP).We retrospectively reviewed 140 consecutive RARPs performed by the same surgical team. Patients were stratiWed based on BMI into two categories: Group I: non-obese (91 patients) and Group II: obese (49 patients). Intraoperative parameters evaluated were: total operative time, estimated blood loss (EBL), intraoperative complications, status of nerve sparing and pelvic lymph node dissection. Postoperative parameters evaluated included positive surgical margin rate, pathological Gleason score and pathological stage, Wnal tumor volume, length of stay (LOS), and postoperative complications. The two groups were statistically comparable for age, PSA, Gleason scores and clinical stages. Mean operative time was greater in the obese group at 300.5 min versus 247.3 min in the non-obese group. Mean EBL in obese patients and non-obese patients were 396.2 and 292.8 ml, respectively. Positive surgical margin rate was 26.5% in obese and 13.1% in non-obese patients. Robotic assisted radical prostatectomy in obese patients is a feasible procedure with acceptable perioperative outcomes and complications. In our study, obesity signiWcantly but negatively aVected operative and postoperative outcomes.
E. P. Castle · M. Woods · R. Thomas · R. Davis Center for Minimally Invasive Urologic Surgery, Department of Urology, Tulane University Health Sciences Center, New Orleans, LA, USA F. Atug (&) Department of Urology, Dicle University School of Medicine, Diyarbakir, Turkey e-mail:
[email protected]
Moreover, obesity was associated with higher grade tumors and higher incidence of positive surgical margins. Consequently, caution is advised in performing RARP in the obese patient in the early part of a learning curve. Keywords Robotic assisted radical prostatectomy · Body mass Ândex · Laparoscopy · Prostate cancer
Introduction Obesity is quantiWed as body mass index (BMI: weight in kilograms/height in square meters). BMI greater than 30 kg/ m2, is increasing in incidence and a major health issue in the United States and elsewhere. Today approximately 31% of adults are obese and it is estimated that this number will be 40% by 2,025 [1]. Obesity can lead to serious health problems such as diabetes, hypertension and coronary artery disease. Also it may aVect surgical and clinical outcomes of patients undergoing various surgical procedures [2, 3]. There is limited data on the impact of obesity on outcomes following radical prostatectomy, laparoscopic radical prostatectomy and particularly robotic assisted radical prostatectomy. Radical retropubic prostatectomy has been reported to be more challenging in obese patients [4]. Furthermore, quality of life impairment has been reported in obese patients after radical prostatectomy [5]. In laparoscopic radical prostatectomy, longer operative times with obese patients has been reported [6]. Perineal radical prostatectomy has been proposed as a preferable technique in obese patients, even in morbidly obese patients [7, 8]. Robotic assisted radical prostatectomy (RARP) is gaining popularity for the treatment of clinically localized prostate cancer [9, 10]. It is important that urologists keep abreast of these new technologies, their limitations, and the
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possibility of incorporating them in urologic practice [11, 12]. The outcomes and complications of RARP are still under scrutiny [13, 14]. However, to date there has been only one study reporting on the impact of obesity in RARP. Ahlering et al. reported the impact of obesity mainly on clinical outcomes amongst 100 RARP patients [15]. In this study we evaluated the impact of BMI on operative time, estimated blood loss (EBL), length of hospital stay (LOS), complications and pathologic outcomes in patients who underwent RARP at our institution.
Materials and methods We retrospectively reviewed 140 consequent RARPs performed by the same surgical team at a single institution between February 2003 and February 2006. Standard preoperative assessment included, age, height, weight, DRE, PSA, Gleason score, clinical stage, TRUS-guided biopsies and abdominal and pelvic computerized tomography, if indicated. Intraoperative parameters were total operative time, estimated blood loss, intraoperative complications, nerve sparing status and pelvic lymph node dissection. Postoperative data consisted of positive surgical margin rate, pathological Gleason sum, pathological stage, Wnal tumor volume, length of hospital stay (LOS), and postoperative complications. Patients were stratiWed based on BMI into two categories: Group I: non-obese ((30 kg/m2) and Group II: obese (30 kg/ m2 or greater). Patients were also stratiWed based on high or low risk factors for positive surgical margins and were compared between the two groups. High risk and low risk clinical proWles for having a positive surgical margins, were assessed according to the risk proWle described by Wieder and Soloway [16]. Specimens were processed according to the technique described by True [17]. The apex and bladder neck cones were amputated and sectioned in the sagittal plane. The remaining specimen was sectioned transversely at 2– 3 mm intervals. All prostate blocks were labeled according to location, which allowed for whole mount reconstruction if necessary. Positive surgical margins were deWned as the presence of tumor tissue on the inked surface of the specimen The collection and use of patient data in this study was approved by our Institutional Review Board. Surgical technique After overcoming our initial learning curve using the intraperitoneal approach, we utilized the extraperitoneal technique. Of the 140 patients, 40 were managed extraperitoneally. Our operative technique for a transperitoneal approach has been described previously [18]. For the extraperitoneal approach, a 2 cm infra-umbilical transverse
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incision was performed Wrst, until reaching the anterior sheath of rectus abdominis fascia is encountered. This fascia was sharply incised and the rectus muscle identiWed on each side of the linea alba. With the help of digital dissection, an extraperitoneal space was created for placement of a dissecting balloon, the subsequent inXation of which creates the extraperitoneal space. A 12-mm camera port was placed in the trocar through this site. Next, the two 8-mm robotic ports were placed under vision about 2 cm below the level of the camera port and lateral to the rectus muscle on either side equidistant from the camera port in an obtuse angle conWguration. Two additional ports (5-mm port and 12-mm port) were placed for the assistant. The surgical resection is identical to the transperitoneal approach. Statistical analysis A two-tailed Student’s t est at the 5% signiWcance level was employed to compare mean values between the two groups. Mean and range results were reported for the studied parameters. Chi-square test at the 5% signiWcance level was employed to compare the complication rates and surgical margin rates between non-obese and obese groups. Fisher exact test was used at the level of 5% signiWcance to test the proportions and the count data of interested variables. All statistical analysis tests were performed with the Statistical Analysis Software 9.1 (SAS Institute, Cary, NC, USA).
Results There were 91 (65 %) non-obese patients (BMI ( 30 kg/m2) and 49 (35%) obese patients (BMI 30 kg/m2 or greater). The characteristics of obese and non-obese patients are shown in Table 1. The groups were statistically comparable for age, PSA, Gleason biopsy sum and clinical stages (Table 1). Pelvic lymphadenectomy was performed in 29% of non-obese and 26% obese patients, whereas nerve sparing was performed in 92% of non-obese and 93% of obese patients. Both were not found to be statistically signiWcant for these two groups at 5% level of signiWcance (Table 1). The mean number of lymph nodes removed per patient was 14.09 in non-obese group and 12.05 in obese group. There were no open conversions in either group. Mean operative time was signiWcantly greater (p value = 0.0031) in the obese group at 301.7 min versus 239.7 min in the non-obese group. Given the diVerence in operative times, we examined if this result was related to diVerences in surgical technique such as transperitoneal (TP) versus extraperitoneal (EP) approach. Both approaches were performed in statistically similar ratios in both groups. Transperitoneal approach was performed in 69% obese and 72.5% of non-obese patients whereas extra-
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Table 1 Patient demographics and preoperative data
Group I non-obese
Group II obese
P value
Patients (n)
91
49
Age (mean)
59.6 § 6.8
58.8 § 7.3
Body mass index (mean)
24.9 § 4.1
32.6 § 3.9
0.05) (Table 4). In addition, nerve sparing, a factor that may aVect margin positivity, was performed in equal numbers amongst the two groups (p > 0.05) (Table 4). In another study Freeland demonstrated that BMI was associated with more advanced disease and higher Gleason scores [25], in line with previously published studies [26, 27]. We also found that obesity was associated with more advanced disease and higher Gleason scores (Table 3). Interestingly, the preoperative Gleason scores and clinical stages were evenly distributed among the obese and nonobese patients. Conclusion Robotic assisted radical prostatectomy in obese patients is a feasible procedure. However, obesity signiWcantly and adversely aVected operative and postoperative outcomes when compared to non-obese patients. Moreover, obesity was associated with higher-grade tumors and higher incidence of surgical positive margins. We advise caution in managing obese patients with RARP until comfort level has been attained and the learning curve has been overcome. References 1. Kopelman PG (2000) Obesity as a medical problem. Nature 404:635 2. Perlow JH, Morgan MA (1994) Massive maternal obesity and perioperative cesarean morbidity. Am J Obstet Gynecol 170:560 3. Pitkin RM (1977) Vaginal hysterectomy in obese women. Obstet Gynecol 49:567 4. Froehner M, Litz R, Manseck A, Hakenberg OW, Leike S, Albrecht DM, et al (2001) Relationship of comorbidity, age and perioperative complication in patients undergoing radical prostatectomy. Urol Int 67:283 5. Anast JW, Sadetsky N, Pasta DJ et al (2005) The impact of obesity on health related quality of life before and after radical prostatectomy (data from capsure). J Urol 173:1132–1138 6. Brown J, David MR, Benjamin L, Douglas MD (2005) Laparoscopic radical prostatectomy and body mass index: An assessment of 151 sequential cases. J Urol 173:442–445
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