Incidence of complications following sentinel lymph node biopsy (SLNBX) correlates with extent of lymphadenectomy (χ2P = .02).
Annual sentinel lymph node biopsy (SLNBX) procedures performed during the period of study (A) and correlation of the annual complication rate with years of experience (B) (r2 = 0.72; P<.05).
Roaten JB, Pearlman N, Gonzalez R, Gonzalez R, McCarter MD. Identifying Risk Factors for Complications Following Sentinel Lymph Node Biopsy for Melanoma. Arch Surg. 2005;140(1):85-89. doi:10.1001/archsurg.140.1.85
Sentinel lymph node biopsy has become routine in the staging of patients with cutaneous melanoma and is presumed to have fewer complications than elective regional lymph node dissection (RLND). However, little information is available to refute or support this assumption.
Risk factors for complications following sentinel lymph node biopsy (SLNBX) can be identified.
Retrospective medical record review.
Patients and Methods
The medical records of 339 consecutive patients undergoing SLNBX for melanoma between 1996 and 2003 at our institution were reviewed for complications.
In our series of 339 patients, 20 complications (5.9%) were observed following SLNBX compared with 15 (19.5%) of 77 patients undergoing RLND during the same period (P<.001). Seroma formation, transient nerve injuries, and minor wound infections were the most frequently observed complications in patients undergoing SLNBX. In contrast, chronic lymphedema and wound infections were the most frequent complications observed in patients undergoing RLND. Patients with comorbid medical conditions had more complications following either SLNBX or RLND than those without. The number of lymph nodes excised and the placement of closed-suction drainage were associated with an increased incidence of complications following SLNBX but not RLND. The incidence of annual complications inversely correlated with the cumulative number of SLNBXs performed during this period.
Sentinel lymph node biopsy can be performed with a low incidence of complications. Experience with SLNBX decreases complications. Patients with more than 1 sentinel lymph node excised or a closed-suction drain placed at the time of SLNBX are at an increased risk of complications.
Sentinel lymph node biopsy (SLNBX) has become a standard of care in the staging of cutaneous melanoma and is now being performed routinely both in academic and private practice.1 Sentinel lymph node biopsy is assumed to have fewer associated complications than a standard complete regional lymph node dissection (RLND) yet little data exist to challenge or support this assumption. A large multi-institutional prospective series with more than 2000 patients reported an overall incidence of 4.6% for complications following SLNBX compared with 23.2% for RLND.2 However, this rate of complications for SLNBX is lower than that reported by several smaller single institution series that cite complication rates in the range of 9% to 30% for SLNBX alone.3- 5 While these early studies have been enlightening, they did not include clinically relevant information regarding relationships between complications and patient-specific risk factors for complications. Identification of such risk factors may ultimately allow for a reduction in complications. The aim of the present study was to identify preoperative and perioperative risk factors associated with complications following SLNBX for melanoma.
A database of all patients undergoing SLNBX for a diagnosis of malignant cutaneous melanoma at the University of Colorado Health Science Center, Denver, between January 1996 and December 2002 was reviewed. Patients routinely underwent preoperative lymphoscintigraphy with the exception of 2 pregnant patients who received only lymphazurin blue injections before exploration. Patients underwent intraoperative lymphatic mapping using a handheld gamma probe. Operative, nuclear medicine, and pathology reports were reviewed for technical details of all procedures including number of nodes removed at operation, number and location of draining lymph node basins, and placement of drains. Preoperative comorbid conditions and complications related to SLNBX or RLND were noted. Additionally, treating physicians were individually queried about patients and possible complications to ensure the thoroughness of the study. Statistical comparisons were conducted using linear regression, χ2 test, t test, or analysis of variance, where appropriate. This study was approved by the local institutional review board at the University of Colorado Health Science Center.
During the period of study, 339 patients underwent a procedure for planned SLNBX. At exploration, a sentinel lymph node could not be identified in 14 patients, giving an overall success rate of 96% (325/339). Of the 325 patients undergoing successful SLNBX, 64 (19.6%) had melanoma metastases.
During the same interval of study, 77 patients underwent RLND for melanoma. Fifty-four of these individuals underwent completion lymph node dissection for positive sentinel node biopsy results, while the remaining 23 RLNDs were performed for the presence of clinically positive lymph nodes. Characteristics of patients undergoing SLNBX and RLND are listed in Table 1.
Among the 339 patients who underwent exploration for SLNBX, there were 20 complications for an overall complication rate of 5.9%. The most common complications were seroma formation (n = 4; 1.2%), nerve injury (n = 3; 0.9%), and wound infection (n = 3; 0.9%). Lymphedema was observed in 2 patients (0.6%). At last follow-up, all complications had resolved with the exception of 1 patient who developed chronic lymphedema of a lower extremity. The median follow-up for patients having complications from SLNBX was 18 months. There were no complications in the 14 patients in whom a sentinel lymph node could not be identified.
Among the 77 patients who underwent RLND, 15 complications were observed for an overall complication rate of 19.5%, significantly higher than that observed for SLNBX (P<.001). The most common complications were lymphedema (n = 6; 7.8%) and wound infection (n = 5; 6.5%). In contrast to SLNBX, in 5 of the 6 patients who developed lymphedema postoperatively, the complication failed to resolve by last follow-up and the condition was presumed to be chronic. Median follow-up for patients having complications from RLND was 18 months. Specific complications of SLNBX and RLND are listed in Table 2.
In the 325 patients undergoing successful SLNBX, 334 nodal basins were sampled. A single draining basin was identified in 301 patients with an overall complication rate per basin of 6.3% vs 24 patients having 2 or more nodal basins sampled with a complication rate per basin of 4.2% (P>.05). The highest complication rate, 29.4% (5/17), was observed in patients undergoing SLNBX of the parotid gland for primary melanoma of the head and neck. Wound-specific complications following parotid SLNBX included 2 hematomas, a seroma, and a transient sensory nerve injury. One patient with a known cardiac history had a minor postoperative myocardial infarction following parotid SLNBX. All complications associated with parotid SLNBX were resolved at last follow-up. The complication rates of specific nodal basins are shown in Table 3.
The mean number of lymph nodes removed at successful SLNBX (n = 325) was 1.86 with a range of 1 to 9 lymph nodes. There is a strong association between the number of nodes excised at SLNBX and the incidence of complications. Patients with complications had a mean ± SD of 2.1 ± 0.8 lymph nodes excised vs 1.8 ± 0.07 lymph nodes for those patients without complications (P<.05). Further analysis showed that patients having 2 nodes (n = 107; 7.5%) or 3 or more nodes (n = 62; 11.3%) excised at SLNBX were at a higher risk of complications than those patients having a single node (n = 156; 3.2%) excised at SLNBX (Figure 1) (χ2P = .02). There was no difference observed in the number of nodes removed from specific basins. The mean number of nodes removed with RLND was 17.7. However, there was no difference observed in the number of lymph nodes removed from patients with and without complications from this procedure (17.7 vs 17.3, respectively; P>.05).
Closed-suction drains were placed in 114 patients undergoing SLNBX. Among these patients, 15 had postoperative complications for an overall complication rate of 13.2% vs 5 complications among the 225 patients (2.2%) who were not drained (χ2P<.001). Of the 15 complications, 14 were wound specific including seroma (n = 3), wound infection (n = 3), hematoma (n = 2), nerve injury (n = 2), dehiscence (n = 2), and lymphedema (n = 2). Two patients undergoing exploration with negative results were drained without complications. There was no difference in the mean number of nodes removed from patients with and without (2.1 vs 1.7 nodes, respectively; P>.05) drains placed at SLNBX. Closed-suction drains were routinely used in patients undergoing RLND.
There were 54 patients in the current study identified as having significant preoperative comorbidities including diabetes, obesity, cardiac disease, or a history of smoking, potentially placing them at increased risk for complications. Of these 54 patients, 5 (9.3%) had complications following SLNBX compared with 5.2% (15/285) in those individuals without comorbid conditions. This difference did not reach statistical significance (P = .21). A similar pattern was observed for RLND where a complication rate of 23.1% was observed for patients with comorbidities vs 12.5% for those without (P = .32).
The number of SLNBX procedures done at our institution increased annually from 1996 to 2002, plateauing around 65 procedures per year (Figure 2A). The incidence of annual complications trended downward during this period from a high of 10% to an incidence of 3.2% during 2002 (Figure 2B). The best correlation with annual complication rate was with cumulative number of cases performed (r2 = 0.72; P<.05). Neither the average number of nodes removed at SLNBX nor the incidence of drain placement changed significantly across the period of study. The failure rate of SLNBX during this period ranged between 0% to 12% and did not correlate with either years of experience with the procedure or cumulative number of SLNBXs performed (data not shown).
Sentinel lymph node biopsy has replaced elective lymph node dissection in the evaluation of regional lymph node metastases for melanoma. Elective lymph node dissection offers minimal benefit to select groups of patients with morbidity rates approaching 60% in some series.6 In contrast, SLNBX is touted as a minimally invasive means of identifying patients with stage III disease who could potentially benefit from further surgical intervention and adjuvant therapy. Although the latter point remains to be demonstrated, the prognostic value of SLNBX is now well established.7 Despite the widespread use of this procedure, there is surprisingly little data available demonstrating the low morbidity of SLNBX. A better understanding of complications associated with any surgical procedure allows better preoperative counseling of patients with regard to expectations of their postoperative course and may guide physicians with intraoperative decisions that could potentially affect the incidence of postoperative complications.
The overall complication rate from SLNBX in the present study is indeed low, 5.9%, compared with 19.5% for patients undergoing RLND. The overall complications and incidence of specific complications in the present study are nearly identical to those reported in the larger prospective study by Wrightson et al.2 Based on this earlier study and the present results, the complication rates reported by Hettiaratchy et al3 and Bonenkamp et al4 seem excessive for this procedure.
Previous authors have failed to identify a correlation between the number of lymph nodes removed at RLND and the incidence of complications.6 The present study demonstrates a correlation between the number of lymph nodes excised and complications following SLNBX. More than one half of the patients in our study (n = 169; 52%) had 2 or more nodes excised at SLNBX placing them at a significantly higher risk of complications. Unfortunately, the number of nodes removed at SLNBX is not a variable that can be controlled, because intentional excision of a single lymph node while leaving other nodes meeting sentinel node criteria would result in an unacceptable false-negative rate.8 However, based on these findings, every effort should be made to exclude nonsentinel nodes from excision and unnecessarily place the patient at risk for complications.
Patients undergoing RLND of the groin have historically had higher rates of wound-specific complications and lymphedema.9 In the present study, there was not an increased incidence of complications associated with SLNBX of the groin compared with other basins. However, with regard to specific nodal basins and SLNBX, an unexpected finding in the present study is the high rate of complications following parotid SLNBX. This finding contrasts with other reports demonstrating low complication rates for SLNBX in this region.10,11 The etiology for this high rate of complications following parotid SLNBX in our series is unclear. However, the denominator of parotid SLNBX in the present study is relatively small, resulting in a large impact of the few minor complications identified.
Closed-suction drains are routinely used in RLND and other soft-tissue procedures at risk for the accumulation of fluid. Wound-specific complications are reduced using closed-suction drainage following axillary dissection for breast cancer.12 Similar results are seen with drain placement following pelvic dissections for gynecologic malignancies.13 However, there is no data available on the use of closed-suction drainage following SLNBX for melanoma. In this study, use of closed-suction drainage is clearly associated with a higher incidence of wound-specific complications. The retrospective nature of this study makes it impossible to discern whether there is a true causal relationship between closed-suction drainage and complications. It may be that the use of closed-suction drains is a surrogate for another variable related to complications from SLNBX, such as the extent of dissection, that, owing to the retrospective nature of the study, we are unable to quantify. However, based on these findings, the routine use of closed suction for SLNBX should be avoided.
The presence of comorbid conditions in patients undergoing surgical procedures is well known to increase the risk of complications.14- 16 In the present study, an increased incidence of complications was observed in patients with comorbid conditions compared with those without, though this difference was not statistically significant. Patients undergoing SLNBX with known comorbid conditions should be informed before the operation that they are at increased risk of wound complications.
The existence of a learning curve for surgical procedures is well established.17,18 With regard to SLNBX for melanoma and breast cancer, the learning curve is generally discussed in the context of failures and false-negative results.19,20 In the present study, we demonstrate that the incidence of complications following SLNBX is inversely related to increased experience with the procedure. Interestingly, our incidence of failures during this period was essentially constant at 4%. These findings suggest, at least for our series, that experience does not necessarily alter the ability to successfully identify the sentinel lymph node but rather may allow identification of the sentinel lymph node without excessive dissection and associated complications.
Sentinel lymph node biopsy can be performed with a significantly lower incidence of complications than RLND if done by an experienced surgeon. Excision of more than 1 node during SLNBX and the placement of a closed-suction drain are associated with an increased risk of postoperative complications. Similar to other surgical procedures, individuals with existing comorbid conditions may also be at an increased risk for complications following SLNBX. Patients identified with these characteristics preoperatively or postoperatively should be counseled regarding an increased risk of complications and monitored carefully in the postoperative period.
Correspondence: Martin McCarter, MD, Department of Surgery, University of Colorado Health Sciences Center, 4200 Ninth Ave, C-311, Denver, CO 80220 (firstname.lastname@example.org).
Accepted for Publication: September 8, 2004.
Funding/Support: This work supported in part by a K12 CA86913 clinical oncology research career development program from the National Institutes of Health, Bethesda, Md.