Objective
Morbid obesity is a known risk factor for the development of endometrial cancer. Several studies have demonstrated the overall feasibility of robotic-assisted surgical staging for endometrial cancer as well as the benefits of robotics compared with laparotomy. However, there have been few reports that have evaluated robotic surgery for endometrial cancer in the supermorbidly obese population (body mass index [BMI], ≥50 kg/m 2 ). We sought to evaluate safety, feasibility, and outcomes for supermorbidly obese patients who undergo robotic surgery for endometrial cancer, compared with patients with lower body mass indices.
Study Design
We performed a retrospective chart review of 168 patients with suspected early-stage endometrial adenocarcinoma who underwent robotic surgery for the management of their disease. Analysis of variance and univariate logistic regression were used to compare patient characteristics and surgical variables across all body weights. Cox proportional hazard regression was used to determine the impact of body weight on recurrence-free and overall survival.
Results
The mean BMI of our cohort was 40.9 kg/m 2 . Median follow up was 31 months. Fifty-six patients, 30% of which had grade 2 or 3 tumors, were supermorbidly obese with a BMI of ≥50 kg/m 2 (mean, 56.3 kg/m 2 ). A comparison between the supermorbidly obese and lower-weight patients demonstrated no differences in terms of length of hospital stay, blood loss, complication rates, numbers of pelvic and paraaortic lymph nodes retrieved, or recurrence and survival. There was a correlation between BMI and conversion to an open procedure, in which the odds of conversion increased with increasing BMI ( P = .02).
Conclusion
Offering robotic surgery to supermorbidly obese patients with endometrial cancer is a safe and feasible surgical management option. When compared with patients with a lower BMI, the supermorbidly obese patient had a similar outcome, length of hospital stay, blood loss, complications, and numbers of lymph nodes retrieved.
With an estimated incidence of 49,560 new cases in 2013, endometrial cancer is the most common gynecologic malignancy in the United States. Obesity is a well-established risk factor for the development of multiple types of cancer, cancer-related death, and all-cause death. Among all cancers, increasing body mass index (BMI) and obesity are associated most strongly with endometrial cancer incidence and death. At present, approximately 35% of the US population is obese, and this number is expected to reach 42% by 2030. Thus, as the incidence of obesity increases, the incidence of endometrial cancer is likely to rise as well.
Obese patients present unique surgical and technical challenges that are related to their multiple perioperative comorbidities and their difficult intraoperative treatment. The cornerstone of treatment for endometrial cancer is hysterectomy with bilateral salpingo-oophorectomy. However, the indication for lymph node dissection in the surgical management of endometrial cancers remains highly controversial. Several studies have demonstrated the overall feasibility of robotic-assisted surgical staging for endometrial cancer and the benefits of robotics compared with laparotomy. In fact, with lower blood loss, fewer infection rates, shorter hospital stay, and faster postoperative recovery, a minimally invasive approach to the surgical management of early-stage endometrial cancer has become a popular option. Several groups recently have evaluated the general feasibility and safety of performing complete robotic surgical staging in the obese and have found it to be safe and efficient. However, there have been few reports that have examined the use of robotic surgery for endometrial cancer staging in the supermorbidly obese patients (BMI, ≥50 kg/m 2 ), and most of these used a BMI of ≥40 kg/m 2 as a cutoff. We examined the safety and feasibility of robotic surgery for endometrial cancer in supermorbidly obese patients and compared their outcomes with the outcomes of patients with lower body mass indices.
Material and Methods
After institutional review board approval was obtained at the University of Iowa Hospitals and Clinics, we conducted a retrospective chart review of 168 women with suspected early-stage endometrial cancer who underwent robotic surgery. Robotic cases were collected from the time robotic surgery was introduced in December 2005 through May 2012. All patients with medical comorbidities underwent preoperative evaluation and proceeded to undergo surgery if medically cleared. Patients were selected for robotic surgery based on the availability of a surgeon who was qualified to use the robotic platform and the availability of the robotic platform itself at our hospital, with no other criteria used to select the surgical approach. It is important to note that, during that same time frame, 1120 patients with endometrial cancer underwent surgery at our institution. All robotic surgeries were performed by 1 of 3 University of Iowa Hospitals and Clinics gynecologic oncologists with the use of the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA), with the robotic program restricted to 1 surgeon during the first few years. Most cases had both residents and fellows involved. From 2005 until December 2011 when the Da Vinci “Si” became available at our institution, all cases were performed on either the original “standard” Da Vinci system or the Da Vinci “S” system. After December 2011, we used a combination of the “S” and “Si” systems based on their availability within our institution. Only endometrial cancer cases with suspected early-stage disease and with preoperative biopsies that indicated endometrioid histologic condition were included in this retrospective study. No cases of traditional laparoscopy were included in our analysis.
Data collected included patient age, BMI, comorbidities, preoperative grade, previous surgeries, procedure performed, operative time, conversion rate, lymph node yield, stage, postoperative complications, need for adjuvant treatment, recurrence, and survival. Operative complications included blood loss that required transfusion and major nerve, vessel, gastrointestinal, or urinary injuries. Postoperative complications included unplanned readmissions within 30 days of surgery, wound complications (seroma, hematoma, wound separation, wound infection), venous thromboembolic events, or any other major events that could be deemed to be a direct result of surgery.
At our institution, positioning of a patient for robotic-assisted surgery starts with placement in the dorsal lithotomy position with the legs in Allen Yellofins stirrups (Allen Medical Systems, Acton, MA) on a standard motorized operating room table that features a maximum 30-degree tilt. After general anesthesia is performed, a nasogastric tube is immediately placed. Both arms are tucked and padded to prevent nerve injuries. Several steps are taken to prevent a patient in steep Trendelenburg from shifting while on the operating table, including the use of a Bean Bag Positioner (AliMed Inc, Dedham, MA). The gel mattress is fastened to the surgical table with tape and conforms to the shape of a patient’s upper and lower body when placed on suction. Four incisions were made for the trocars: 1 vertical 12-mm supraumbilical incision at 24-28 cm above the symphysis pubis, two 8-mm lateral incisions, and one 10-mm left upper quadrant incision. The left upper quadrant port was used for accessory instruments that included suction/irrigators and manipulators. This port placement technique has optimized our access to the pelvis and paraaortic regions, even in the supermorbidly obese patients. To allow for a completion of the paraaortic lymph node dissection, a paddle or a fan often was used for retraction, with sigmoid epiploica plication to the left pelvic side wall in cases of increased central adiposity.
The practice at our institution until early 2010 was to perform comprehensive surgical staging with both bilateral pelvic and paraaortic lymph node dissection for all patients who were diagnosed with endometrial cancer, regardless of their histologic condition or grade of disease. Lymph node boundaries were as described in the Gynecology Oncology Group Surgical Procedures Manual. Starting in 2010, there was a paradigm shift at our institution, wherein lymph node dissection was omitted for patients with grade 1 endometrial cancer with <50% myometrial invasion assessed intraoperatively by frozen section analysis. Lymph node dissection was performed on all other patients with endometrial cancer. Although slightly modified, this change was a direct response to the publication of the “Mayo criteria.”
Statistical analyses included analysis of variance and univariate logistic regression to compare findings across all body weights. To determine whether BMI had a significant impact on recurrence-free and overall survival, a Cox proportional hazard regression was used. All values were 2-sided and carried out at the 5% level of significance with SAS software (version 9.3; SAS Institute Inc, Cary, NC).
Results
Before analysis was performed, patient data were stratified according to BMI ( Table 1 ). The mean BMI of our total patient cohort was 40.9 kg/m 2 . Our study included 56 supermorbidly obese patients with a BMI of ≥50 kg/m 2 (mean BMI, 56.3 kg/m 2 ), who were compared with 112 patients with a BMI of <50 kg/m 2 (mean BMI, 34.2 kg/m 2 ). The 2 groups did not differ significantly in demographic variables such as age, grade, stage, histologic condition, or previous abdominal surgeries, but there were more medical comorbidities in the BMI of ≥50 kg/m 2 group as noted in Table 2 . Medical comorbidities were obtained from the chart review and were classified by organ system.
| BMI, kg/m 2 | n (%) |
|---|---|
| Underweight, <18.5 | 0 |
| Normal weight, 18.5-24.9 | 11 (6.5) |
| Overweight, 25-29.9 | 28 (16.6) |
| Obesity, 30-34.9 | 26 (15.5) |
| Severe obesity, 35-39.9 | 22 (13.1) |
| Morbid obesity, 40-49.9 | 25 (14.9) |
| Super obesity, ≥50 | 56 (33.3) |
| Variable | Body mass index, n (%) | P value | |
|---|---|---|---|
| <50 kg/m 2 (n = 112) | ≥50 kg/m 2 (n = 56) | ||
| Mean age, y | 60.68 | 56.17 | .07 |
| Histologic condition | .33 | ||
| Endometrioid | 103 (92) | 54 (96.4) | |
| Others a | 9 (8) | 2 (3.6) | |
| Grade | .58 | ||
| 1 | 68 (60.7) | 38 (67.8) | |
| 2 | 34 (30.4) | 15 (26.8) | |
| 3 | 10 (8.9) | 3 (5.4) | |
| Stage | .25 | ||
| IA | 80 (71.4) | 44 (78.5) | |
| IB | 14 (12.5) | 4 (7.2) | |
| II | 7 (6.3) | 6 (10.7) | |
| >II | 11 (9.8) | 2 (3.6) | |
| Comorbidity | < .0001 | ||
| Yes | 74 (66.1) | 53 (94.6) | |
| No | 38 (33.9) | 3 (5.4) | |
| Previous abdominal surgeries | .266 | ||
| Yes | 70 (62.5) | 30 (53.6) | |
| No | 42 (38.5) | 26 (46.4) | |
a Includes serous, clear cell, mucinous, carcinosarcoma, and mixed histologic condition.
Table 3 gives a comparison of operative factors that are stratified by BMI. When lymph node dissection was performed, there were no differences in the yields of pelvic (16.6 vs 18.9 nodes; P = .29) or paraaortic (4.8 vs 4.2 nodes; P = .23) lymph nodes between the 2 groups. It is important to note that lymph node counts compared between groups did not include cases in which conversion to laparotomy occurred. However, it was noted that, as BMI increased, patients were less likely to undergo lymph node dissection ( P < .0001). In fact, as shown in Table 3 , 14 of the 16 patients in our cohort who did not undergo lymph node dissection were found to be supermorbidly obese. In contrast, only 2 of the 112 patients in the BMI of <50 kg/m 2 group did not undergo comprehensive surgical staging. This might have resulted in a statistically shorter operative time, defined as time from incision to wound closure, for the supermorbidly obese patients (348.6 vs 269.1 minutes; P < .0001). When evaluating overall time in the operating room, patients with a BMI of ≥50 kg/m 2 still had a shorter operative time compared with patients with a BMI of <50 kg/m 2 (360.3 vs 396.5 minutes).
| Variable | Body mass index | P value | |
|---|---|---|---|
| <50 kg/m 2 (n = 112) | ≥50 kg/m 2 (n = 56) | ||
| Procedure, n (%) | |||
| Hysterectomy + bilateral salpingo-oophorectomy | 2 (1.8) | 14 (25) | < .0001 |
| Hysterectomy + bilateral salpingo-oophorectomy + lymph nodes | 110 (98.2) | 42 (75) | |
| Pelvic lymph nodes, n | .29 | ||
| Mean | 16.6 | 18.9 | |
| Median (range) | 15 (5–42) | 17 (4–47) | |
| Paraaortic lymph nodes, n | .23 | ||
| Mean | 4.8 | 4.2 | |
| Median (range) | 5 (0–10) | 3 (0–9) | |
| Estimated blood loss, mL | .17 | ||
| Mean | 115.1 | 150.0 | |
| Median (range) | 100 (25–650) | 88 (25–1000) | |
| Operative time, min | < .0001 | ||
| Mean | 348.6 | 269.1 | |
| Median (range) | 320 (157–663) | 260 (111–470) | |
| Conversion, n (%) | .04 | ||
| Yes | 9 (8) | 11 (19.6) | |
| No | 103 (92) | 45 (80.4) | |
However, when considering only patients who underwent a lymph node dissection, the time from incision to closure was significantly shorter for patients with a BMI of <50 kg/m 2 ( P = < .001). However, the overall time spent in the operating room was not significantly different between the 2 groups ( P = .34). Interestingly, estimated blood loss, which was determined by the volume that was collected in the suction and sponges and assessed by the surgical and anesthesia teams, was not significantly higher for the supermorbidly obese patients (150.0 vs 115.1 mL; P = .17). Our rate of conversion to laparotomy for the entire cohort was 11.83%. It appeared that this rate increased with increasing BMI. Eleven of the 20 patients who were converted to open procedures were supermorbidly obese ( P = .04; Table 3 ).
As seen in Table 4 , which details a comparison of postoperative factors stratified by BMI, there were no differences in the types or frequencies of postoperative complications between the 2 groups ( P = .81). In fact, there were 19 total abdominal wound infections that ranged from cellulitis to wound separation. Of these, 7 infections occurred in the supermorbidly obese group. No gastrointestinal or urinary injuries were noted in any patients, and only 2 patients required intraoperative blood transfusions (BMI, 27.1 and 26.9 kg/m 2 ). Of the 7 patients who experienced postoperative ileus that required a prolonged hospital stay, only 2 patients were supermorbidly obese. Similarly, even when we included cases of conversion to laparotomy occurred, the overall length of hospital stay did not significantly differ between the 2 groups (2.1 vs 2.2 days; P = .52).
| Categories | Body mass index | P value | |
|---|---|---|---|
| <50 kg/m 2 (n = 112) | ≥50 kg/m 2 (n = 56) | ||
| Complications, n (%) | .81 | ||
| None | 89 (79.4) | 45 (80.4) | |
| Ileus | 5 (4.4) | 2 (3.6) | |
| Wound complication | 12 (10.8) | 7 (12.4) | |
| Gastrointestinal | 0 | 0 | |
| Genitourinary | 0 | 0 | |
| Other | 6 (5.4) | 2 (3.6) | |
| Mean length of stay, d | 2.2 | 2.1 | .52 |
We also examined overall survival and recurrence-free survival within our cohort, as stratified by BMI. Stratifications were divided into 2 categories: BMI <50 and ≥50 kg/m 2 . BMI stratification produced no differences in overall survival (hazard ratio, 0.51; 95% confidence interval, 0.15–1.76; P = .29) or recurrence-free survival (hazard ratio, 0.97; 95% confidence interval, 0.34–2.75; P = .95) when patients with a BMI ≥50 kg/m 2 were compared with patients with a lower BMI. Median follow-up time within our cohort was 31 months. There were 2 deaths in our cohort that occurred within 30 days of surgery. The first patient had a BMI of 37.8 kg/m 2 and a significant cardiac history and died at home on postoperative day 21 from undetermined causes. The second patient had a BMI of 50.9 kg/m 2 and died of a fatal pulmonary embolism on postoperative day 7. Neither of these patients had been discharged on anticoagulation medication.
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