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A comparison of robotic and laparoscopic minimally invasive adrenalectomy for adrenal malignancies
Jonathan J. Hue1D . Peter Ahorukomeye2 . Katherine Bingmer1 . Lauren Drapalik1 . John B. Ammori1 . Scott M. Wilhelm1 . Luke D. Rothermel1 . Christopher W. Towe1
Received: 5 August 2021 / Accepted: 19 October 2021 / Published online: 1 November 2021 @ The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2021
Abstract
Background Although guidelines recommend open adrenalectomy for most resectable adrenal malignancies, minimally invasive adrenalectomies are performed. Robotic adrenalectomies have become more popular recently, but there is a paucity of literature comparing laparoscopic and robotic resections.
Methods Patients who underwent a planned minimally invasive adrenalectomy for adrenal malignancies (adrenocortical car- cinoma, malignant pheochromocytoma, other carcinoma) were identified in the National Cancer Database. The primary out- come was the conversion rate from minimally invasive to open. Other post-operative outcomes and survival were compared. Results 416 patients (76.5%) underwent a laparoscopic adrenalectomy and 128 (23.5%) underwent a robotic operation. Demographics and clinical characteristics were similar. Approximately 19% of tumors resected by a minimally invasive approach were> 10 cm. The intra-operative conversion rate was decreased among robotic adrenalectomies relative to lapa- roscopic on univariate (7.8% vs. 18.3%, p=0.005) and multivariable (odds ratio 0.39, p=0.01) analyses. Using marginal standardization, there was a stepwise increase in the conversion rate as tumor size increased (<5, 5-10,> 10 cm) for laparo- scopic (7.5%, 18.0%, 33.2%) and robotic (3.1%, 8.3%, 17.3%) adrenalectomies. Operations which required conversion had a greater margin positivity rate, greater length of stay, and an association with poor overall survival.
Conclusion In contrast to most clinical guidelines, minimally invasive adrenalectomies are being performed on large malig- nant tumors. A laparoscopic approach was associated with a greater conversion rate and subsequent poor outcomes. If a surgeon is not planning an open adrenalectomy, but adrenal malignancy is a possibility, robotic adrenalectomy may be the preferred approach for resectable adrenal tumors.
Keywords Minimally invasive surgery · Adrenalectomy · Adrenocortical carcinoma · Pheochromocytoma
Consensus guidelines recommend open adrenalectomy for practically all cases of adrenocortical carcinoma (ACC) [1-4] and large pheochromocytomas [5] to minimize the risk of tumor capsule violation, margin positivity, and sub- sequent recurrence. However, guidelines from two European societies suggest that a laparoscopic adrenalectomy could be considered for potentially malignant adrenal tumors ≤ 6 cm without invasion of adjacent organs [4]. Importantly, these
guidelines note this should only be attempted by a highly experienced surgeon and open adrenalectomy should remain the standard of care for lesions that are highly suspicious for ACC [4]. In contrast to this point, recent administrative database studies have demonstrated that many minimally invasive adrenalectomies (MIA) are being performed among patients with large adrenal tumors, including ACC [6-8]. This is worrisome, as larger tumors are associated with an increased likelihood of conversion from MIA to open, and past studies have demonstrated that conversion was associ- ated with poor short- and long-term outcomes [7, 8].
With increased utilization and improved spatial resolu- tion of cross-sectional imaging, the incidence of incidental adrenal nodules has increased over the last decade [9]. For many adrenal pathologies, adrenalectomy plays a key role in the treatment algorithm [1]; however, the optimal surgical
☒ Christopher W. Towe Christopher.Towe@UHHospitals.org
1 Department of Surgery, University Hospitals Cleveland Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106-5011, USA
2 Case Western Reserve University School of Medicine, Cleveland, OH, USA
approach to adrenalectomy remains a topic of debate [10]. Resection of adrenal pathologies are particularly impor- tant areas of research, as they are technically demanding. Laterality plays an important role: right-sided tumors are often more difficult to resect due to their intimate anatomic relationship with the inferior vena cava, leading to a higher rate of intra-operative conversion [8]. A meta-analysis of 12 studies reported a similar conversion rate when compar- ing laparoscopic and robotic adrenalectomies for a variety of adrenal lesions [10]. However, one recent report dem- onstrated that robotic adrenalectomy was associated with a reduced likelihood of conversion relative to laparoscopic (odds ratio 0.33, p=0.046) among patients with ACC using multivariable logistic regression, but this finding was not explored further [7]. Despite this finding, the authors recom- mended that open adrenalectomy remain standard of care for ACC due to the high conversion rate (19.4%) and subsequent poor outcomes [8], which is in line with current guidelines [1-6].
Many may argue that open adrenalectomy should remain the gold standard for adrenal malignancies, but surgical innovation and experiences among other oncologic resec- tions suggest that MIA will continue to be performed and improved [10]. Although robotic operations have become more popular in recent years, there is a paucity of literature examining the association between pathologic and long-term outcomes based on MIA approach (robotic or laparoscopic) in adrenal cancers. Herein, we aimed to detail outcomes after adrenalectomy for several adrenal malignancies using the National Cancer Database (NCDB). We hypothesized that robotic adrenalectomy may be associated with improved short-term post-operative outcomes.
Materials and methods
Institutional assurances
The Institutional Review Board at University Hospitals Cleveland Medical Center has deemed that retrospective analyses of public, deidentified data sets are exempt from review.
Data source
The NCDB is a nationwide database, jointly maintained by the American Cancer Society and the American College of Surgeons. This database receives patient information from Commission on Cancer-accredited hospitals throughout the United States. It contains deidentified information on over 70% of all new malignancies diagnosed in the United States each year. The NCDB Participant User File data diction- ary contains definitions of variables used in this study [11].
The accuracy of the data reported and statistical analyses performed are not monitored nor verified by the American College of Surgeons or American Cancer Society. The con- clusions presented represent those of the authors.
Patient cohort
Adult patients who underwent an adrenalectomy between 2010 and 2016 were categorized based on International Classification for Diseases in Oncology (3rd Edition) codes: pheochromocytoma (8700), ACC (8370), or other carcinoma (8000, 8004, 8010, 8013, 8032, 8033, 8041, 8246, 8270, 8290, 8310). Tumor location codes included were C740 (adrenal cortex), C741 (adrenal medulla), and C749 (adrenal gland, not otherwise specified). Only patients with invasive disease (behavior code 3) were included. Patients with clini- cal nodal involvement (clinical N-stage 1) or distant meta- static disease (clinical M-stage 1) were excluded. This study period was chosen, as operative approach was not recorded in the NCDB prior to 2010.
Exposure
Patients who underwent an adrenalectomy were stratified by planned minimally invasive operative approach: laparo- scopic or robotic. Patients who underwent a planned open adrenalectomy were not included in this analysis. Specific operation codes 30 (simple or partial surgical removal), 40 (total surgical removal), and 60 (radical surgery, par- tial or total removal with a resection or other organs) were included.
Outcomes
The primary outcome was intra-operative conversion from MIA to open. Secondary outcomes were other short-term post-operative outcomes (margin positivity, length of stay) and long-term overall survival, defined as the time from diagnosis to death or last follow-up.
Statistical analysis
Statistical comparisons between groups were performed using the Wilcoxon rank sum test for continuous variables or Pearson’s chi-squared test or Fisher’s exact test for categori- cal variables. Multivariable logistic regression was used to further explore intra-operative conversion, margin positivity, and length of stay ≥ 5 days. Variables included in multivari- able models were significant (p<0.05) on univariate analy- ses. Multivariable models were also clustered on facility identifiers to account for intraclass correlation for patients treated at the same hospital. The association between mini- mally invasive approach and conversion was also analyzed
using marginal standardization, which calculates the prob- ability of an outcome variable (conversion) adjusted to the weight of confounders (tumor size, laterality). Multivariable Cox proportional hazards regression was used to analyze overall survival. The NCDB does not include survival data for patients diagnosed in 2016, thus these patients were not included in survival analyses. StataSE v16.0 (Statacorp LLC, College Station, TX) was used for statistical analyses. A p-value <0.05 was used to indicate statistical significance.
Results
Demographic and clinical characteristics
In total, 544 patients underwent an MIA: 416 (76.5%) were laparoscopic and 128 (23.5%) were robotic-assisted (Table 1). There were no differences in demographic variables including age, sex, race, or primary insurance payor based on starting MIA approach. A greater propor- tion of patients who underwent a robotic adrenalectomy received care at a community facility relative to patients who had a laparoscopic adrenalectomy (42.0% vs. 30.6%, p=0.051). Most patients in both operative groups had a diagnosis of ACC (laparoscopic: 68.8%, robotic: 76.6%),
| Laparoscopic | Robotic | p-value | |
|---|---|---|---|
| N | 416 (76.5%) | 128 (23.5%) | – |
| Age, years (median, IQR) | 57 (46, 67) | 58 (48, 67) | 0.343 |
| Sex | 0.772 | ||
| Male | 175 (42.1%) | 52 (40.6%) | |
| Female | 241 (57.9%) | 76 (59.4%) | |
| Race | 0.991 | ||
| White | 353 (84.9%) | 108 (84.4%) | |
| Black | 47 (11.3%) | 15 (11.7%) | |
| Other | 16 (3.8%) | 5 (3.9%) | |
| Primary insurance payor | 0.610 | ||
| Private | 221 (53.1%) | 65 (50.8%) | |
| Medicare | 136 (32.7%) | 49 (38.3%) | |
| Medicaid, other government | 40 (9.6%) | 9 (7.0%) | |
| None, unknown | 19 (4.6%) | 5 (3.9%) | |
| Charlson-Deyo comorbidity index | 0.736 | ||
| 0 | 273 (65.6%) | 83 (64.8%) | |
| 1 | 103 (24.8%) | 35 (27.3%) | |
| ≥2 | 40 (9.6%) | 10 (7.8%) | |
| Facility type | 0.051 | ||
| Community | 109 (30.6%) | 47 (42.0%) | |
| Academic/Research | 186 (52.3%) | 53 (47.3%) | |
| Integrated Network | 61 (17.1%) | 12 (10.7%) | |
| Distance to facility, miles (median, IQR) | 14.1 (5.7, 37.8) | 14.4 (5.6, 28.4) | 0.742 |
| Diagnosis | 0.056 | ||
| Pheochromocytoma | 113 (27.2%) | 22 (17.2%) | |
| ACC | 276 (68.8%) | 98 (76.6%) | |
| Non-ACC carcinoma | 17 (4.1%) | 8 (6.2%) | |
| Laterality | 0.152 | ||
| Right | 199 (47.8%) | 52 (40.6%) | |
| Left | 217 (52.2%) | 76 (59.4%) | |
| Size, cm (median, IQR) | 7.0 (4.6, 9.5) | 6.3 (4.0, 9.5) | 0.251 |
| <5 cm | 113 (28.1%) | 41 (33.3%) | 0.534 |
| 5-10 cm | 210 (52.2%) | 59 (48.0%) | |
| > 10 cm | 79 (19.7%) | 23 (18.7%) |
and the minority had a pheochromocytoma or other car- cinoma subtype. Median tumor size was similar (6.3 vs. 7.0 cm, p=0.251): approximately 19% of all patients had a tumor > 10 cm.
Facility characteristics
In total, there were 308 individual facilities which per- formed a minimally invasive adrenalectomy during the study period: 67% only performed laparoscopic adrenal- ectomies, 20% only performed robotic adrenalectomies, and 13% performed both (data not shown). However, of hospitals which only performed robotic operations, 92% (57 of 62 facilities) only performed one minimally invasive adrenalectomy over the study period, which was greater as compared to facilities which only per- formed laparoscopic adrenalectomies (65.4%, 134 of 205 facilities).
Conversion
A greater proportion of laparoscopic adrenalectomies required conversion to open as compared to robotic resec- tions (18.3% vs. 7.8%, Table 2) on univariate analysis. We further explored intra-operative conversion using multi- variable logistic regression (Table 3). When controlling for tumor size, laterality, diagnosis, and patient age, robotic adrenalectomies were associated with a reduced likelihood of conversion relative to laparoscopic resections [odds ratio (OR) 0.391, 95% confidence interval (CI) 0.188-0.814]. Left-sided tumors were associated with a reduced likelihood of conversion as compared to right-sided tumors (OR 0.279, 95% CI 0.168-0.462). Increasing tumor size was also asso- ciated with a stepwise increased likelihood of conversion.
The association between minimally invasive approach and conversion was further explored using marginal standardiza- tion with logistic regression (Table 4; Fig. 1A). There was a stepwise increase in the probability of intra-operative con- version among laparoscopic adrenalectomies as tumor size
| Laparoscopic | Robotic | p-value | |
|---|---|---|---|
| Conversion | 76 (18.3%) | 10 (7.8%) | 0.005 |
| Positive margin | 76 (20.3%) | 19 (16.8%) | 0.410 |
| Length of stay, days (median, IQR) | 3 (2,5) | 2 (2, 4) | 0.203 |
| Unplanned readmission | 12 (2.9%) | 2 (1.6%) | 0.421 |
| 90-day mortality | 18 (5.0%) | 3 (3.0%) | 0.624 |
| Minimally invasive | Converted | p-value | |
| Positive margin | 70 (16.9%) | 25 (34.3%) | 0.001 |
| Length of stay, days (median, IQR) | 2 (1, 4) | 5 (3,6) | <0.001 |
| Unplanned readmission | 11 (2.4%) | 3 (3.5%) | 0.549 |
| 90-day mortality | 15 (3.9%) | 6 (7.9%) | 0.148 |
| Conversion | Conversion, tumor 5-10 cm | |||||||
|---|---|---|---|---|---|---|---|---|
| OR | 95% CI | p | OR | 95% CI | p | |||
| Robotic vs. laparoscopic | 0.391 | 0.188 | 0.814 | 0.012 | 0.274 | 0.090 | 0.837 | 0.023 |
| Age | 0.986 | 0.971 | 1.003 | 0.098 | 0.979 | 0.954 | 1.004 | 0.096 |
| Diagnosis | ||||||||
| Pheochromocytoma | Ref | – | – | - | Ref | - | - | - |
| ACC | 1.281 | 0.703 | 2.334 | 0.418 | 1.831 | 0.764 | 4.387 | 0.175 |
| Non-ACC carcinoma | 4.010 | 1.211 | 13.279 | 0.023 | 6.827 | 1.425 | 32.712 | 0.016 |
| Left vs. right | 0.279 | 0.168 | 0.462 | <0.001 | 0.488 | 0.244 | 0.975 | 0.042 |
| Tumor size | - | - | - | - | ||||
| <5 cm | Ref | - | - | - | - | - | ||
| 5-10 cm | 2.864 | 1.382 | 5.935 | 0.005 | - | |||
| > 10 cm | 6.932 | 3.059 | 15.711 | <0.001 | - | - | - | - |
Model was clustered on facility identifiers
| Laparoscopic | Robotic | |||||
|---|---|---|---|---|---|---|
| Probability (%) | 95% CI (%) | Probability (%) | 95% CI (%) | |||
| Size | ||||||
| <5 cm | 7.5 | 3.0 | 11.9 | 3.1 | 0.5 | 5.8 |
| 5-10 cm | 18.0 | 12.7 | 23.4 | 8.3 | 3.0 | 13.5 |
| > 10 cm | 33.2 | 23.5 | 42.8 | 17.3 | 7.2 | 27.4 |
| Laterality | ||||||
| Right | 27.0 | 21.1 | 33.0 | 13.6 | 5.9 | 21.3 |
| Left | 10.3 | 6.3 | 14.2 | 4.5 | 1.5 | 7.4 |
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increased (<5 cm: 7.5%; 5-10 cm: 18.0%; > 10 cm: 33.2%). A similar trend was seen for robotic adrenalectomies, but the probabilities were lower for all tumor size groupings (<5 cm: 3.1%; 5-10 cm: 8.3%; > 10 cm: 17.3%). Adjusted probabilities of conversion were also lower among robotic adrenalectomies relative to laparoscopic when controlling for tumor laterality (Table 4; Fig. 1B).
As previous single institution studies have reported an overall conversion rate < 10% during MIA [12, 13], we fur- ther explored tumors 5-10 cm as adjusted probabilities of conversion during robotic (8.3%) and laparoscopic (18.3%) adrenalectomy were below and above this value, respec- tively. Multivariable logistic regression demonstrated that robotic adrenalectomy was again associated with a reduced odds of conversion relative to laparoscopic (OR 0.274, 95% CI 0.090-0.837, Table 3) among patients with a 5-10 cm tumor.
Other pathologic and peri-operative outcomes
The positive margin rate was similar between laparoscopic and robotic adrenalectomies (20.3% vs. 16.8%, Table 2). The positive margin rate (16.9% vs. 34.3%, p=0.001) and
length of stay (2 vs. 5 days, p<0.001) were both signifi- cantly lower when comparing complete MIA and those which required conversion (Table 2). On multivariable logistic regression, minimally invasive approach was not associated with margin positivity (robotic vs. laparoscopic: OR 0.741, 95% CI 0.433-1.267, Supplemental Table 1) or length of stay ≥ 5 days (OR 1.024, 95% CI 0.655-1.601, Supplemental Table 2). Conversion was associated with a greater odds of margin positivity (OR 2.439, 95% CI 1.302-4.568) and length of stay ≥ 5 days (OR 3.467, 95% CI 2.051-5.859).
Survival
Multivariable Cox proportional hazards regression did not identify an associated survival benefit for robotic adrenal- ectomy as compared to laparoscopic [hazard ratio (HR) 0.860, 95% CI 0.556-1.330, Table 5]. Conversion to open was associated with poor survival (HR 1.504, 95% CI 1.005-2.250). Other variables associated with poor sur- vival were increasing tumor size and advanced age.
| HR | 95% CI | p-value | ||
|---|---|---|---|---|
| Robotic vs. laparoscopic | 0.860 | 0.556 | 1.330 | 0.498 |
| Conversion | 1.504 | 1.005 | 2.250 | 0.047 |
| Age | 1.029 | 1.014 | 1.044 | <0.001 |
| Charlson-Deyo comorbidity index | ||||
| 0 | Ref | – | – | – |
| 1 | 1.067 | 0.709 | 1.606 | 0.756 |
| ≥2 | 1.538 | 0.945 | 2.504 | 0.083 |
| Diagnosis | ||||
| Pheochromocytoma | Ref | – | – | – |
| ACC | 2.494 | 1.449 | 4.292 | 0.001 |
| Non-ACC carcinoma | 1.861 | 0.742 | 4.671 | 0.186 |
| Size, cm | ||||
| <5 cm | Ref | – | – | – |
| 5-10 cm | 1.896 | 1.218 | 2.951 | 0.005 |
| > 10 cm | 2.370 | 1.379 | 4.071 | 0.002 |
Model was adjusted for insurance payor, and was clustered on facility identifiers
Discussion
As new technologies are developed, surgeons will be faced with important decisions regarding the optimal operative approach. There is a fine line between maintaining patient safety and advancing the field of surgery through inno- vation [14]. To date, comparisons between laparoscopic and robotic adrenalectomy often include a mixture of both benign and malignant pathologies [12, 13, 15, 16], and no randomized controlled trials have been performed among patients with adrenal cancers. Morino et al. previously randomized 20 patients to laparoscopic or robotic adre- nalectomy for benign adrenal lesions and deemed laparo- scopic resections were superior due to reduced cost, lower morbidity, and greater accessibility [17]. However, in this limited trial, the conversion rates were 0% for robotic adre- nalectomies, but 40% for laparoscopic resections. These data have not been replicated in additional randomized tri- als. Herein, we analyze these two MIA approaches among adrenal malignancies using the NCDB and demonstrate several key points. Using multivariable models and mar- ginal standardization, we identify an association between a laparoscopic approach and an increased likelihood of conversion, relative to a robotic approach. This associa- tion was particularly striking among patients with tumors 5-10 cm. Similar to past reports, conversion from MIA to open was also associated with poor post-operative out- comes including an increased likelihood of margin posi- tivity, length of stay ≥ 5 days, and poor overall survival.
The authors speculate that the physical act of convert- ing from MIA to open is not the driver of poor outcomes. Conversion is likely a marker of aggressive disease, which may not have been identified on pre-operative evaluation. It is important to explicitly state that conversion should indeed be performed for uncontrolled bleeding, unanticipated risk of tumor rupture, or unexpected adjacent organ invasion. As is implied by European guidelines [4], patient selection for MIA is important.
Data analyzing conversion rates during MIA are con- flicting in the literature, and the question of laparoscopic or robotic remains controversial. A previous analysis of patients who underwent an MIA within the National Inpa- tient Sample (NIS) did not demonstrate a difference in con- version rates when comparing laparoscopic and robotic adre- nalectomy, as rates were <2% for both approaches [16]. The discrepancy between these data and the findings presented in our current analysis may be due to the study population uti- lized, as both benign and malignant adrenal pathologies were included in the aforementioned study. Additionally, the NIS database does not include specific diagnoses (ACC, malig- nant pheochromocytoma, etc.), and less than 3% of included tumors were malignant [16]. Three prior meta-analyses also reported similar conversion rates between robotic and lapa- roscopic adrenalectomies, but again these analyses were not specific to adrenal malignancies [10, 18, 19]. While lapa- roscopic and robotic approaches appear equivalent among benign pathologies, robotic resections may have advantages that are highlighted when faced with adrenal malignancies. However, the high overall rate of margin positivity (19.5%) and conversion (15.8%) suggest the importance of appro- priate patient selection if a minimally invasive approach is considered in patients with a potential adrenal malignancy.
Although robotic adrenalectomy is a newer operation [20-22], these data suggest it may be the preferred approach for a variety of malignant adrenal pathologies, if a mini- mally invasive approach is pursued. As stated previously, open adrenalectomy is still recommended by societal guide- lines for adrenal cancers [1-6]. While our findings are likely multifactorial, robotic-assisted resections offer several key advantages relative to a laparoscopic approach, which are summarized elsewhere [23]. However, the authors speculate the improved visualization technologies (3 dimensional (3D) vs. 2D) and greater instrument dexterity (wristed vs. rigid) used in robotic platforms may be especially important when resecting adrenal cancers, due to the increased likelihood of vascular or local invasion [8]. Of note, among “complete” MIA (i.e., those which did not require conversion) in our analysis, robotic and laparoscopic resections were associ- ated with similar rates of positive margins, extended length of stay, and overall survival. These data indicate that robotic and laparoscopic adrenalectomies appear to be equiva- lent when conversion is not required, further stressing the
importance of proper patient selection to identify patients who should undergo a planned open adrenalectomy.
In our analysis, approximately one in five MIA was per- formed for a malignant tumor > 10 cm. While this is not recommended by clinical guidelines (and is not part of the authors’ practice), this is further support of the importance of this manuscript. Surgeons across the country are perform- ing MIA on large adrenal cancers, which are associated with a significantly greater likelihood of conversion (independent of MIA approach), extended length of stay, and poor overall survival. However, it is plausible that surgeons are unknow- ingly resecting large adrenal malignancies via a laparoscopic or robotic approach, as pre-operative diagnosis of malig- nancy can be challenging on occasion [24, 25].
To this point, we also identified a rather unexpected dis- crepancy in MIA approach. A greater proportion of robotic adrenalectomies are being performed at community facili- ties, as compared to academic facilities. Past studies have demonstrated disparities in access to robotic platforms [26], but this finding is difficult to further elucidate based on limi- tations in the NCDB. There were 103 individual facilities which performed 128 robotic adrenalectomies (average 1.2; range 1-4) and 246 facilities which performed 416 laparo- scopic adrenalectomies (average 1.7; range 1-7) over the 7-year study period. A past report estimated that the learn- ing curve for robotic adrenalectomy was 12 operations [27]. Although these case volumes do not include benign patholo- gies, these data are rather concerning as experience with MIA is still in the early phase, yet a significant number of attempts are already being made at resecting large tumors. Additionally, a recent survey-based analysis demonstrated that adrenal surgeons tend to perform minimally invasive techniques they were exposed to in fellowship [28]. While nearly 100% of fellows performed laparoscopic adrenalec- tomies in fellowship, just 13% gained robotic experience [28]. Thus, some surgeons may strictly perform laparo- scopic resections, while others may perform robotic adre- nalectomies. To this point, only 13% of facilities included in this study performed both a laparoscopic and robotic adrenalectomy.
Our analysis has several important limitations which should be noted. Perhaps most importantly, the NCDB does not capture details on the reason for conversion, such as hemorrhage, adhesions, tumor capsule violation, prolonged operative time, or improper trocar placement. Importantly, several recent studies among primarily benign lesions have reported longer operative times with robotic adrenalecto- mies, but potentially reduced blood loss [15, 29]; however, these data are not available in the NCDB. Additionally, we cannot account for differences in a surgeon’s definition of conversion, whether it was a diagnostic laparoscopy fol- lowed by primarily open dissection or significant mini- mally invasive dissection followed by conversion due to
intra-operative issues. Similarly, the NCDB does not record the exact operative approach: transabdominal or retroperi- toneal. Individual surgeon adrenalectomy volumes (open, laparoscopic, or robotic) for either benign or malignant tumors cannot be determined using the NCDB: multivari- able models were clustered on the facility identification code in an attempt to account for differences in hospital MIA volume. Data on tumor capsule violation or recurrences are not available in the NCDB, thus the only long-term outcome analyzed was overall survival. We cannot account for miss- ing or incorrect data within the database. Despite these limi- tations, we provide a thorough analysis of MIA for adrenal malignancies and demonstrate that robotic adrenalectomy may be the preferred approach if a minimally invasive adre- nalectomy is considered, although open adrenalectomy cur- rently still remains standard of care.
Conclusion
Robotic adrenalectomy was associated with a reduced likelihood of intra-operative conversion relative to a lapa- roscopic approach for patients with adrenal malignancies. As definitive pre-operative diagnosis of adrenal lesions can be challenging, robotic adrenalectomy may be the preferred approach if a minimally invasive adrenalectomy is selected for a potentially malignant adrenal tumor.
Supplementary Information The online version contains supplemen- tary material available at https://doi.org/10.1007/s00464-021-08827-x.
Funding None.
Declarations
Disclosures Dr. Towe discloses that he is a consultant to Sig Medical, Zimmer Biomet, Medtronic, and Atricure, but that these relationships have not influenced the work or its conclusions. The other authors have no disclaimers, sources of funding, or financial relationships that could inappropriately influence this work and its conclusions.
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