Journal of Surgical Oncology 2014;110:888–892
Indocyanine Green and Fluorescence Lymphangiography for Sentinel Lymph Node Identification in Cutaneous Melanoma JORDAN M CLOYD, MD,1* IRENE L WAPNIR, MD,1 BLAKE M READ, MD,1 SUSAN SWETTER, 1 AND RALPH S GRECO, MD
2 MD,
1 Department of Surgery, Stanford University, Stanford, CA Department of Dermatology, Stanford University, Stanford, CA
2
Background and Objectives: Sentinel lymph node (SLN) biopsy has become the standard method of determining regional lymph node involvement in cutaneous melanoma. Although traditionally performed via injection of radioisotope tracers and blue dyes, fluorescent lymphangiography with indocyanine green (ICG) is an attractive alternative. Methods: Fifty two consecutive patients with cutaneous melanoma of the trunk or extremities underwent SLNB. Preoperative lymphoscintigraphy was performed with technetium‐99m sulfur colloid (TSC). Peritumoral intradermal injection of isosulfan blue (ISB) and ICG was then performed. Successful identification of a sentinel lymph node via each modality was then assessed. Results: A total of 77 lymph nodes were identified from the 52 patients (range 1–3). The majority of melanomas were extremity‐based, superficial spreading type, and had SLN localized to the axilla. There were no complications related to IcG administration. Rates of SLN detection were 96.2% for TSC, 59.6% for ISB, and 88.5% for IcG (P < 0.05 for ICG vs ISB). On univariate logistic regression analysis, no factors were found to be associated with failure of ICG. Conclusions: Fluorescent lymphangiography using ICG is an effective method of SLN identification in patients with cutaneous melanoma of the trunk and extremities. When ICG and TSC are used in combination, ISB offers no additional advantage and may be safely omitted.
J. Surg. Oncol. 2014;110:888–892. ß 2014 Wiley Periodicals, Inc.
KEY WORDS: melanoma; sentinel lymph node biopsy; indocyanine green; lymphadenectomy; nuclear medicine; isosulfan blue
INTRODUCTION Regional lymph node metastasis remains one of the most important prognostic factors for cutaneous melanoma [1,2]. Sentinel lymph node (SLN) biopsy has become the standard approach to lymph node staging in clinically node‐negative patients. Current approaches to sentinel lymph node identification utilize blue dyes and radioisotope colloids with reported success rates of 95–99% [3,4]. However, each of these modalities has disadvantages. Isosulfan blue causes skin staining and has been associated with anaphylactic reactions. Methylene blue may cause skin necrosis as well as staining at the injection site. Both blue dyes are generally considered suboptimal as a lone modality. Radioisotope tracers lack real‐time visualization and information on lymph node depth. Preoperative injections in nuclear medicine are painful and can be associated with operating room delays. In addition, despite their high success rates, the combination of radioisotope colloid and a blue dye is still associated with a 3–5% false negative rate [5,6]. Novel methods of SLN identification would therefore be welcomed. Recently, near‐infrared (NIR) fluorescence imaging using indocyanine green has emerged as an alternative method of SLN identification. With an excellent safety profile, good tissue penetration, and real time intra‐ operative imaging capabilities, indocyanine green (ICG) offers potential advantages to radiotracer‐based lymphoscintigraphy. It has shown to be an effective modality, superior to methylene blue, for SLNB in breast cancer [7,8] and early experience in melanoma has also been promising [9–12]. The purpose of the current study was to study the effectiveness of ICG in performing SLN biopsy for cutaneous melanoma compared to traditional methods.
MATERIALS & METHODS The study was approved by the Institutional Review Board (IRB). Patients undergoing SLNB in conjunction with or after wide local
ß 2014 Wiley Periodicals, Inc.
excision of a primary cutaneous melanoma of the trunk or extremity from January to December, 2013 were considered eligible. Included were patients 18 years of age or older, clinically node negative, with no palpable lymphadenopathy or previous lymphadenectomy and without known allergies to iodine, shellfish, blue dye, or ICG. All patients signed informed consent. On the morning of surgery, each patient underwent peritumoral injection of approximately 1.0 mCi technetium‐99m sulfur colloid (TSC) in the nuclear medicine department with delayed lymphoscintigraphic imaging. After induction of general anesthesia and appropriate patient positioning, 4 ml of Lymphazurin isosulfan blue (ISB) (Tyco Healthcare Inc, Norwalk, CT) and 2 ml (2.5 mg/ml) of ICG (IC‐GreenTM, Pulsion Medical Systems, Feldkirchen, Germany) were injected intradermally in a peritumoral fashion. Real time imaging was performed using a specialized infrared camera‐computer system (SPY EliteTM, Novadaq Technologies Inc; Ontario, Canada) to look for fluorescence within dermal or subcutaneous lymphatics. Approximately 5–7 min after injection, an incision was made in the selected nodal basin. SPY imaging was repeated to determine the presence of fluorescent nodes. The SLN biopsy was then performed using a combination of the handheld gamma probe, ICG fluorescence and blue dye visualization. ICG was defined as successful if fluorescence was seen in situ and helped guide the lymph node dissection
*Correspondence to: Jordan M Cloyd, MD, Department of Surgery, Stanford University, 300 Pasteur Dr, MC5641, Stanford, CA 94305. Fax: 650‐852‐ 3430. Email: [email protected] Received 11 April 2014; revised manuscript received 1 July 2014; Accepted 10 July 2014 DOI 10.1002/jso.23745 Published online 13 August 2014 in Wiley Online Library (wileyonlinelibrary.com).
Indocyanine Green for SLN Biopsy (Figure 1). All radioisotope hot, blue, and fluorescent lymph nodes were harvested. Patients with positive SLNB on final pathology returned to the operating room for completion lymph node dissection (CLND). The efficacy of each modality and concordance with final histopathology was then assessed. The analysis was performed in two ways: first, the sensitivity of each modality to detect at least one lymph node per patient; and second, the sensitivity of the modalities for each lymph node retrieved. Statistical significance between groups was tested via Chi Square with a < 0.05. Univariate logistic regression analysis was performed to evaluate the association with demographic and oncologic factors and the failure of ICG.
RESULTS Fifty‐two consecutive patients underwent SLN biopsy during the study period using all three modalities. Patient characteristics are listed in Table I. Mean age was 59 (range 20–90) and 53.8% were women. The majority of cases were superficial spreading melanoma (69.2%), extremity based (57.7%) and revealed a SLN based in the axilla (75.0%). A total of 77 lymph nodes were excised and evaluated. Mean number of SLNs removed was 1.5 with a range of 1–3. A SLN was successfully identified in 51 out of 52 (98.1%) patients. The one patient, where all three lymphatic mapping techniques were unsuccessful, had a palpable black lymph node which was excised and eventually determined to contain metastatic melanoma. At least one node was identified by TSC, ISB, or ICG in 96.2%, 59.6%, and 88.5% of cases, respectively. ICG and TSC were found to be statistically significantly better than ISB at identifying SLN (P < 0.0001, Figure 2). TSC, ISB, and ICG detected 88.3%, 54.5%, and 88.3%, respectively, of all lymph nodes tested (Table II). The use of ICG generated an additional lymph node in six different patients that were not identified by TSC or ISB (Figure 3). Interestingly, all excised lymph nodes, except the black SLN, demonstrated fluorescence ex vivo and there was minimal residual fluorescence in the operative cavity after the SLNB was completed. On univariate logistic regression, no specific variables were found to be associated with failure of ICG (Table III). Eleven (21.2%) patients had positive lymph nodes and later underwent CLND. TSC, ISB, and ICG were successful in 81.8%, 55.6%, and 81.8%, respectively, of these patients with lymph node metastasis. TSC failed to identify a SLN in two patients, one had lymph node metastasis and one was detected by ICG alone. Complications included four seromas (three after CLND, one after SLN biopsy) and one superficial wound infection after CLND. There were no complications related to ICG injection.
DISCUSSION Accurate nodal staging has important prognostic and therapeutic implications for primary cutaneous melanoma [1,2]. Regional
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TABLE I. Patient Characteristics Age (range) Gender Male (%) Female (%) BMI (range) Histology Superficial spreading (%) Nodular (%) Lentigo maligna (%) Acral lentiginous (%) Other (%) Breslow depth, mm (range) Primary location Extremity (%) Trunk (%) Lymph node location Axilla (%) Inguinal (%) Both (%) No. of lymph nodes (range) CLND (%)
58.5 (20–90)
24 (46.2) 28 (53.8) 28.6 (16.2‐40.1) 36 7 4 2 3 2.9
(69.2) (13.5) (7.7) (3.8) (5.8) (0.3‐19)
30 (57.7) 22 (42.3) 39 11 2 1.5 11
(75.0) (21.2) (3.8) (1‐3) (21.2)
lymphadenectomy improves melanoma‐specific survival and overall survival for both clinically apparent lymph node metastasis and micrometastasis [3,13]. Since its inception, SLN mapping and biopsy have become the standard method for regional lymph node staging [14]. First performed only with vital blue dyes, its accuracy was improved with the addition of radioisotope colloids [15]. Recently, fluorescence lymphangiography using ICG has been studied as an alternative method of lymphatic mapping in order to overcome their associated drawbacks. These include the logistical requirements of preoperative lymphoscintigraphy, handling of radioactive agents, blue dye related hives and anaphylaxis, and the non‐zero false negative rate of SLN biopsy using both methods [6]. ICG is a fluorescent dye with several distinct advantages which make it suitable for SLN mapping. It offers excellent tissue penetration with real time NIR imaging. Unlike with radioisotopes, a handheld probe is unnecessary and the dye provides direct visual feedback. ICG has no major side effects and there are no radiation concerns to patient or provider. It is routinely used to assess skin perfusion in breast cancer related procedures and reconstructive surgery [16]. Its use has proven effective for SLN mapping and biopsy in breast cancer [7,8,17,18] and more recent series have suggested similar efficacy in melanoma [9,11,12,19]. Jain et al. found the use of ICG lymphangiography to be successful in 13 of 15 patients (87%) with melanoma [20] while
Fig. 1. Representative images demonstrating (A) axillary sentinel lymph node biopsy with (B) in situ fluorescence guidance and (C) ex vivo confirmatory imaging using ICG. Journal of Surgical Oncology
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Fig. 2. Rates of successful identification of at least one sentinel lymph node in each patient (A) and percentage of all lymph nodes removed that were positive (B) using technetium‐99m (TSC), isosulfan blue (ISB), and indocyanine green (ICG). P < 0.05.
Namikawa and Yamazaki found ICG to successfully identify a SLN in all 49 patients they studied [11]. In their series of 25 patients with melanoma and 65 lymph nodes excised, Gilmore et al. found that albumin bound ICG successfully identified 64 (98%) of the nodes. Using a low dose escalation protocol, they concluded that 500 mm was the optimal intradermal dose [12]. Our findings are in agreement with the results of a randomized trial in breast cancer patients showing that blue dye may safely be omitted when radioisotope is used in conjunction with ICG for lymphatic mapping [7]. Preoperative lymphoscintigraphy has the advantage of guiding the surgeon to the nodal basin of interest, especially in truncal melanomas. Unfortunately, in our experience, transcutaneous visualization of lymphatic channels or lymph node fluorescence was inconsistent and therefore could not be relied upon for identification of the sentinel nodal basin. In other words, fluorescent nodes were only consistently visualized after the skin incision was made. Other investigators have described similar concerns. Namikawa et al. retrospectively studied this phenomenon and found that despite 99% of lymph nodes demonstrating fluorescence “after skin incision”, only 63% were detected trans‐ cutaneously “before skin incision” [21]. Furthermore, van der Vorst et al. preliminarily tested whether radioisotope injections could be eliminated by intentionally not using a handheld Geiger probe for the initial portion of each dissection. In 25%, SLN identification was not possible with only ICG and the handheld probe was required [7]. Except in extremity lesions where the draining lymph node basin is largely predictable, preoperative lymphoscintigraphy will remain necessary. A new hybrid tracer that combines ICG and Tc‐99m nanocolloid is also currently being investigated [22]. Although the reported efficacy of SLN biopsy with blue dye ranges considerably in the literature [5,14,23–25], we acknowledge a relatively low success rate of SLN identification with ISB in this study. Since both ISB and ICG were injected peritumorally simultaneously, one possible explanation for this finding is that ISB and ICG are competitive with each other. ICG, with its relatively low molecular weight, may be more favorably uptaken by the SLN. This is supported by previous studies that
TABLE II. Effectiveness of Technetium‐99m, Isosulfan Blue, and Indocyanine Green in Identifying Sentinel Lymph Nodes for Melanoma Mode
Patients (%)
All Lymph Nodes (%)
Technetium‐99m Isosulfan Blue Indocyanine Green
50/52 (96.2) 31/52 (59.6) 46/52 (88.5)
68/77 (88.3) 42/77 (54.5) 68/77 (88.3)
Journal of Surgical Oncology
Fig. 3. Venn diagram demonstrating percentage of lymph nodes detected by each modality: technetium‐99m (TSC), isosulfan blue (ISB), and indocyanine green (ICG).
have shown consistently delayed visualization of blue dye when used in combination with ICG [26,27]. Despite the low success rate of ISB in this study, our findings are similar to others which have reported inferior results of blue dyes compared to ICG [7,11,28]. Some investigators have raised concerns that ICG may be overly sensitive for SLN identification. In fact, previous studies have demonstrated a greater number of lymph nodes excised with the use of ICG fluorescence [11,28–31]. ICG’s high tissue penetration and rapid lymphatic circulation time may promote the detection of non‐sentinel lymph nodes with lesser florescence. Our study design did not have a comparative control group that would allow us to test this directly, however, six patients (11.5%) had an additional lymph node removed that would otherwise have not been identified by traditional techniques. Establishment of a signal‐to‐background threshold, similar to Geiger count thresholds, may be helpful. Since ICG is a small particle tracer that travels quickly through lymphatics, secondary (non‐sentinel) lymph nodes may be identified and unnecessarily removed as sentinel nodes.
TABLE III. Univariate Logistic Regression for Association With Failure of Indocyanine Green to Detect a Sentinel Lymph Node Odds Ratio (95% Confidence Interval) Age Male gender Body Mass Index Histology: Non superficial spreading melanoma Breslow depth > 1 mm Location: trunk LN Metastasis LN Location: inguinal Technetium‐99m positive Isosulfan Blue positive
1.01 1.64 0.88 0.72 1.60 0.82 1.29 1.31
(0.96–1.05) (0.40–6.65) (0.77–1.01) (0.14–3.79)
(0.31–8.35) (0.20–3.34) (0.26–6.35) (0.24–7.10) N/A 2.79 (0.64–12.10)
Indocyanine Green for SLN Biopsy This may especially be problematic in patients with multiple lymph node basins as the ICG tracer may have migrated after the first SLN dissection. ICG was well tolerated in our patients with no immediate or short term complications related to administration as reported by others [32]. Intradermal ICG is easy to administer, similar to blue dye injections, and the SPY EliteTM system is fairly intuitive to use. It is unclear whether a threshold number of procedures are needed to obtain competency. We, as others, did not find evidence of a learning curve throughout the one year study period [12]. Perhaps with ongoing experience, the success rate with ICG would continue to improve. The main limitation of the current study is its single institution and retrospective design. In addition, our analysis is limited to melanoma of the trunk and extremities. Previous studies have investigated the use of NIR fluorescence in melanoma of the head and neck, showing promise [10]. Future work should include randomized controlled trials comparing the use of ICG to standard methods of SLN mapping with outcome measures, such as number of lymph nodes excised and need for handheld Geiger probe, clearly defined.
CONCLUSIONS NIR fluorescent lymphangiography using ICG safely facilitates SLN identification for patients with cutaneous melanoma of the trunk and extremities. When ICG and TSC are used in combination, ISB offers no additional advantage and may be safely omitted.
ACKNOWLEDGMENT We would like to thank Shannon Meyer for her invaluable assistance in the course of this study.
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10. Hayashi T, Furukawa H, Oyama A, et al.: Sentinel lymph node biopsy using real‐time fluorescence navigation with indocyanine green in cutaneous head and neck/lip mucosa melanomas. Head Neck 2012;34:758–761.doi: 10.1002/hed.21651 11. Namikawa K, Yamazaki N: Sentinel lymph node biopsy guided by indocyanine green fluorescence for cutaneous melanoma. Eur J Dermatol 2011;21:184–190.doi: 10.1684/ejd.2010.1237 12. Gilmore DM, Khullar OV, Gioux S, et al.: Effective low‐dose escalation of indocyanine green for near‐infrared fluorescent sentinel lymph node mapping in melanoma. Ann Surg Oncol 2013;20:2357–2363.doi: 10.1245/s10434‐013‐2905‐x 13. Balch CM, Soong S, Ross MI, et al.: Long‐term results of a multi‐ institutional randomized trial comparing prognostic factors and surgical results for intermediate thickness melanomas (1.0 to 4.0 mm). Intergroup Melanoma Surgical Trial. Ann Surg Oncol 2000;7:87–97. 14. Morton DL, Wen DR, Wong JH, et al.: Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg (Chicago IL) 1960;1992; 127:392–399. 15. Albertini JJ, Cruse CW, Rapaport D, et al.: Intraoperative radio‐ lympho‐scintigraphy improves sentinel lymph node identification for patients with melanoma. Ann Surg 1996;223:217–224. 16. Wapnir I, Dua M, Kieryn A, et al.: Intraoperative imaging of nipple perfusion patterns and ischemic complications in nipple‐sparing mastectomies. Ann Surg Oncol 2014;21:100–106.doi: 10.1245/ s10434‐013‐3214‐0 17. Kitai T, Inomoto T, Miwa M, et al.: Fluorescence navigation with indocyanine green for detecting sentinel lymph nodes in breast cancer. Breast Cancer Tokyo Jpn 2005;12:211–215. 18. Troyan SL, Kianzad V, Gibbs‐Strauss SL, et al.: The FLARE intraoperative near‐infrared fluorescence imaging system: A first‐in‐ human clinical trial in breast cancer sentinel lymph node mapping. Ann Surg Oncol 2009;16:2943–2952.doi: 10.1245/s10434‐009‐ 0594‐2 19. Van der Vorst JR, Schaafsma BE, Verbeek FPR, et al.: Dose optimization for near‐infrared fluorescence sentinel lymph node mapping in patients with melanoma. Br J Dermatol 2013;168:93– 98.doi: 10.1111/bjd.12059 20. Jain V, Phillips BT, Conkling N, et al.: Sentinel lymph node detection using laser‐assisted indocyanine green dye lymphangiography in patients with melanoma. Int J Surg Oncol 2013;2013:904– 907. 21. Namikawa K, Tsutsumida A, Tanaka R, et al.: Limitation of indocyanine green fluorescence in identifying sentinel lymph node prior to skin incision in cutaneous melanoma. Int J Clin Oncol 2014;19:198–203.doi: 10.1007/s10147‐013‐0524‐y 22. Brouwer OR, Buckle T, Vermeeren L, et al.: Comparing the hybrid fluorescent‐radioactive tracer indocyanine green‐99mTc‐nanocolloid with 99mTc‐nanocolloid for sentinel node identification: A validation study using lymphoscintigraphy and SPECT/CT. J Nucl Med Off Publ Soc Nucl Med 2012;53:1034–1040.doi: 10.2967/ jnumed.112.103127 23. Liu Y, Truini C, Ariyan S: A randomized study comparing the effectiveness of methylene blue dye with lymphazurin blue dye in sentinel lymph node biopsy for the treatment of cutaneous melanoma. Ann Surg Oncol 2008;15:2412–2417.doi: 10.1245/ s10434‐008‐9953‐7 24. Zengel B, Yararbas U, Sirinocak A, et al.: Sentinel lymph node biopsy in breast cancer: Review on various methodological approaches. Tumori 2013;99:149–153.doi: 10.1700/1283. 14184 25. Lin KM, Patel TH, Ray A, et al.: Intradermal radioisotope is superior to peritumoral blue dye or radioisotope in identifying breast cancer sentinel nodes. J Am Coll Surg 2004;199:561–566.doi: 10.1016/j.jamcollsurg.2004.06.018 26. Mieog JSD, Troyan SL, Hutteman M, et al.: Toward optimization of imaging system and lymphatic tracer for near‐infrared fluorescent sentinel lymph node mapping in breast cancer. Ann Surg Oncol 2011;18:2483–2491.doi: 10.1245/s10434‐011‐1566‐x 27. Hutteman M, Mieog JSD, van der Vorst JR, et al.: Randomized, double‐blind comparison of indocyanine green with or without albumin premixing for near‐infrared fluorescence imaging of
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sentinel lymph nodes in breast cancer patients. Breast Cancer Res Treat 2011;127:163–170.doi: 10.1007/s10549‐011‐1419‐0 28. Korn JM, Tellez‐Diaz A, Bartz‐Kurycki M, et al.: Indocyanine green SPY elite‐assisted sentinel lymph node biopsy in cutaneous melanoma. Plast Reconstr Surg 2014;133:914–922.doi: 10.1097/ PRS.0000000000000006 29. Fujisawa Y, Nakamura Y, Kawachi Y, et al.: Indocyanine green fluorescence‐navigated sentinel node biopsy showed higher sensitivity than the radioisotope or blue dye method, which may help to reduce false‐negative cases in skin cancer. J Surg Oncol 2012;106:41–45.doi: 10.1002/jso.23045 30. Tagaya N, Yamazaki R, Nakagawa A, et al.: Intraoperative identification of sentinel lymph nodes by near‐infrared fluorescence
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Indocyanine Green and Fluorescence Lymphangiography for Sentinel Lymph Node Identification in Cutaneous Melanoma JORDAN M CLOYD, MD,1* IRENE L WAPNIR, MD,1 BLAKE M READ, MD,1 SUSAN SWETTER, 1 AND RALPH S GRECO, MD
2 MD,
1 Department of Surgery, Stanford University, Stanford, CA Department of Dermatology, Stanford University, Stanford, CA
2
Background and Objectives: Sentinel lymph node (SLN) biopsy has become the standard method of determining regional lymph node involvement in cutaneous melanoma. Although traditionally performed via injection of radioisotope tracers and blue dyes, fluorescent lymphangiography with indocyanine green (ICG) is an attractive alternative. Methods: Fifty two consecutive patients with cutaneous melanoma of the trunk or extremities underwent SLNB. Preoperative lymphoscintigraphy was performed with technetium‐99m sulfur colloid (TSC). Peritumoral intradermal injection of isosulfan blue (ISB) and ICG was then performed. Successful identification of a sentinel lymph node via each modality was then assessed. Results: A total of 77 lymph nodes were identified from the 52 patients (range 1–3). The majority of melanomas were extremity‐based, superficial spreading type, and had SLN localized to the axilla. There were no complications related to IcG administration. Rates of SLN detection were 96.2% for TSC, 59.6% for ISB, and 88.5% for IcG (P < 0.05 for ICG vs ISB). On univariate logistic regression analysis, no factors were found to be associated with failure of ICG. Conclusions: Fluorescent lymphangiography using ICG is an effective method of SLN identification in patients with cutaneous melanoma of the trunk and extremities. When ICG and TSC are used in combination, ISB offers no additional advantage and may be safely omitted.
J. Surg. Oncol. 2014;110:888–892. ß 2014 Wiley Periodicals, Inc.
KEY WORDS: melanoma; sentinel lymph node biopsy; indocyanine green; lymphadenectomy; nuclear medicine; isosulfan blue
INTRODUCTION Regional lymph node metastasis remains one of the most important prognostic factors for cutaneous melanoma [1,2]. Sentinel lymph node (SLN) biopsy has become the standard approach to lymph node staging in clinically node‐negative patients. Current approaches to sentinel lymph node identification utilize blue dyes and radioisotope colloids with reported success rates of 95–99% [3,4]. However, each of these modalities has disadvantages. Isosulfan blue causes skin staining and has been associated with anaphylactic reactions. Methylene blue may cause skin necrosis as well as staining at the injection site. Both blue dyes are generally considered suboptimal as a lone modality. Radioisotope tracers lack real‐time visualization and information on lymph node depth. Preoperative injections in nuclear medicine are painful and can be associated with operating room delays. In addition, despite their high success rates, the combination of radioisotope colloid and a blue dye is still associated with a 3–5% false negative rate [5,6]. Novel methods of SLN identification would therefore be welcomed. Recently, near‐infrared (NIR) fluorescence imaging using indocyanine green has emerged as an alternative method of SLN identification. With an excellent safety profile, good tissue penetration, and real time intra‐ operative imaging capabilities, indocyanine green (ICG) offers potential advantages to radiotracer‐based lymphoscintigraphy. It has shown to be an effective modality, superior to methylene blue, for SLNB in breast cancer [7,8] and early experience in melanoma has also been promising [9–12]. The purpose of the current study was to study the effectiveness of ICG in performing SLN biopsy for cutaneous melanoma compared to traditional methods.
MATERIALS & METHODS The study was approved by the Institutional Review Board (IRB). Patients undergoing SLNB in conjunction with or after wide local
ß 2014 Wiley Periodicals, Inc.
excision of a primary cutaneous melanoma of the trunk or extremity from January to December, 2013 were considered eligible. Included were patients 18 years of age or older, clinically node negative, with no palpable lymphadenopathy or previous lymphadenectomy and without known allergies to iodine, shellfish, blue dye, or ICG. All patients signed informed consent. On the morning of surgery, each patient underwent peritumoral injection of approximately 1.0 mCi technetium‐99m sulfur colloid (TSC) in the nuclear medicine department with delayed lymphoscintigraphic imaging. After induction of general anesthesia and appropriate patient positioning, 4 ml of Lymphazurin isosulfan blue (ISB) (Tyco Healthcare Inc, Norwalk, CT) and 2 ml (2.5 mg/ml) of ICG (IC‐GreenTM, Pulsion Medical Systems, Feldkirchen, Germany) were injected intradermally in a peritumoral fashion. Real time imaging was performed using a specialized infrared camera‐computer system (SPY EliteTM, Novadaq Technologies Inc; Ontario, Canada) to look for fluorescence within dermal or subcutaneous lymphatics. Approximately 5–7 min after injection, an incision was made in the selected nodal basin. SPY imaging was repeated to determine the presence of fluorescent nodes. The SLN biopsy was then performed using a combination of the handheld gamma probe, ICG fluorescence and blue dye visualization. ICG was defined as successful if fluorescence was seen in situ and helped guide the lymph node dissection
*Correspondence to: Jordan M Cloyd, MD, Department of Surgery, Stanford University, 300 Pasteur Dr, MC5641, Stanford, CA 94305. Fax: 650‐852‐ 3430. Email: [email protected] Received 11 April 2014; revised manuscript received 1 July 2014; Accepted 10 July 2014 DOI 10.1002/jso.23745 Published online 13 August 2014 in Wiley Online Library (wileyonlinelibrary.com).
Indocyanine Green for SLN Biopsy (Figure 1). All radioisotope hot, blue, and fluorescent lymph nodes were harvested. Patients with positive SLNB on final pathology returned to the operating room for completion lymph node dissection (CLND). The efficacy of each modality and concordance with final histopathology was then assessed. The analysis was performed in two ways: first, the sensitivity of each modality to detect at least one lymph node per patient; and second, the sensitivity of the modalities for each lymph node retrieved. Statistical significance between groups was tested via Chi Square with a < 0.05. Univariate logistic regression analysis was performed to evaluate the association with demographic and oncologic factors and the failure of ICG.
RESULTS Fifty‐two consecutive patients underwent SLN biopsy during the study period using all three modalities. Patient characteristics are listed in Table I. Mean age was 59 (range 20–90) and 53.8% were women. The majority of cases were superficial spreading melanoma (69.2%), extremity based (57.7%) and revealed a SLN based in the axilla (75.0%). A total of 77 lymph nodes were excised and evaluated. Mean number of SLNs removed was 1.5 with a range of 1–3. A SLN was successfully identified in 51 out of 52 (98.1%) patients. The one patient, where all three lymphatic mapping techniques were unsuccessful, had a palpable black lymph node which was excised and eventually determined to contain metastatic melanoma. At least one node was identified by TSC, ISB, or ICG in 96.2%, 59.6%, and 88.5% of cases, respectively. ICG and TSC were found to be statistically significantly better than ISB at identifying SLN (P < 0.0001, Figure 2). TSC, ISB, and ICG detected 88.3%, 54.5%, and 88.3%, respectively, of all lymph nodes tested (Table II). The use of ICG generated an additional lymph node in six different patients that were not identified by TSC or ISB (Figure 3). Interestingly, all excised lymph nodes, except the black SLN, demonstrated fluorescence ex vivo and there was minimal residual fluorescence in the operative cavity after the SLNB was completed. On univariate logistic regression, no specific variables were found to be associated with failure of ICG (Table III). Eleven (21.2%) patients had positive lymph nodes and later underwent CLND. TSC, ISB, and ICG were successful in 81.8%, 55.6%, and 81.8%, respectively, of these patients with lymph node metastasis. TSC failed to identify a SLN in two patients, one had lymph node metastasis and one was detected by ICG alone. Complications included four seromas (three after CLND, one after SLN biopsy) and one superficial wound infection after CLND. There were no complications related to ICG injection.
DISCUSSION Accurate nodal staging has important prognostic and therapeutic implications for primary cutaneous melanoma [1,2]. Regional
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TABLE I. Patient Characteristics Age (range) Gender Male (%) Female (%) BMI (range) Histology Superficial spreading (%) Nodular (%) Lentigo maligna (%) Acral lentiginous (%) Other (%) Breslow depth, mm (range) Primary location Extremity (%) Trunk (%) Lymph node location Axilla (%) Inguinal (%) Both (%) No. of lymph nodes (range) CLND (%)
58.5 (20–90)
24 (46.2) 28 (53.8) 28.6 (16.2‐40.1) 36 7 4 2 3 2.9
(69.2) (13.5) (7.7) (3.8) (5.8) (0.3‐19)
30 (57.7) 22 (42.3) 39 11 2 1.5 11
(75.0) (21.2) (3.8) (1‐3) (21.2)
lymphadenectomy improves melanoma‐specific survival and overall survival for both clinically apparent lymph node metastasis and micrometastasis [3,13]. Since its inception, SLN mapping and biopsy have become the standard method for regional lymph node staging [14]. First performed only with vital blue dyes, its accuracy was improved with the addition of radioisotope colloids [15]. Recently, fluorescence lymphangiography using ICG has been studied as an alternative method of lymphatic mapping in order to overcome their associated drawbacks. These include the logistical requirements of preoperative lymphoscintigraphy, handling of radioactive agents, blue dye related hives and anaphylaxis, and the non‐zero false negative rate of SLN biopsy using both methods [6]. ICG is a fluorescent dye with several distinct advantages which make it suitable for SLN mapping. It offers excellent tissue penetration with real time NIR imaging. Unlike with radioisotopes, a handheld probe is unnecessary and the dye provides direct visual feedback. ICG has no major side effects and there are no radiation concerns to patient or provider. It is routinely used to assess skin perfusion in breast cancer related procedures and reconstructive surgery [16]. Its use has proven effective for SLN mapping and biopsy in breast cancer [7,8,17,18] and more recent series have suggested similar efficacy in melanoma [9,11,12,19]. Jain et al. found the use of ICG lymphangiography to be successful in 13 of 15 patients (87%) with melanoma [20] while
Fig. 1. Representative images demonstrating (A) axillary sentinel lymph node biopsy with (B) in situ fluorescence guidance and (C) ex vivo confirmatory imaging using ICG. Journal of Surgical Oncology
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Fig. 2. Rates of successful identification of at least one sentinel lymph node in each patient (A) and percentage of all lymph nodes removed that were positive (B) using technetium‐99m (TSC), isosulfan blue (ISB), and indocyanine green (ICG). P < 0.05.
Namikawa and Yamazaki found ICG to successfully identify a SLN in all 49 patients they studied [11]. In their series of 25 patients with melanoma and 65 lymph nodes excised, Gilmore et al. found that albumin bound ICG successfully identified 64 (98%) of the nodes. Using a low dose escalation protocol, they concluded that 500 mm was the optimal intradermal dose [12]. Our findings are in agreement with the results of a randomized trial in breast cancer patients showing that blue dye may safely be omitted when radioisotope is used in conjunction with ICG for lymphatic mapping [7]. Preoperative lymphoscintigraphy has the advantage of guiding the surgeon to the nodal basin of interest, especially in truncal melanomas. Unfortunately, in our experience, transcutaneous visualization of lymphatic channels or lymph node fluorescence was inconsistent and therefore could not be relied upon for identification of the sentinel nodal basin. In other words, fluorescent nodes were only consistently visualized after the skin incision was made. Other investigators have described similar concerns. Namikawa et al. retrospectively studied this phenomenon and found that despite 99% of lymph nodes demonstrating fluorescence “after skin incision”, only 63% were detected trans‐ cutaneously “before skin incision” [21]. Furthermore, van der Vorst et al. preliminarily tested whether radioisotope injections could be eliminated by intentionally not using a handheld Geiger probe for the initial portion of each dissection. In 25%, SLN identification was not possible with only ICG and the handheld probe was required [7]. Except in extremity lesions where the draining lymph node basin is largely predictable, preoperative lymphoscintigraphy will remain necessary. A new hybrid tracer that combines ICG and Tc‐99m nanocolloid is also currently being investigated [22]. Although the reported efficacy of SLN biopsy with blue dye ranges considerably in the literature [5,14,23–25], we acknowledge a relatively low success rate of SLN identification with ISB in this study. Since both ISB and ICG were injected peritumorally simultaneously, one possible explanation for this finding is that ISB and ICG are competitive with each other. ICG, with its relatively low molecular weight, may be more favorably uptaken by the SLN. This is supported by previous studies that
TABLE II. Effectiveness of Technetium‐99m, Isosulfan Blue, and Indocyanine Green in Identifying Sentinel Lymph Nodes for Melanoma Mode
Patients (%)
All Lymph Nodes (%)
Technetium‐99m Isosulfan Blue Indocyanine Green
50/52 (96.2) 31/52 (59.6) 46/52 (88.5)
68/77 (88.3) 42/77 (54.5) 68/77 (88.3)
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Fig. 3. Venn diagram demonstrating percentage of lymph nodes detected by each modality: technetium‐99m (TSC), isosulfan blue (ISB), and indocyanine green (ICG).
have shown consistently delayed visualization of blue dye when used in combination with ICG [26,27]. Despite the low success rate of ISB in this study, our findings are similar to others which have reported inferior results of blue dyes compared to ICG [7,11,28]. Some investigators have raised concerns that ICG may be overly sensitive for SLN identification. In fact, previous studies have demonstrated a greater number of lymph nodes excised with the use of ICG fluorescence [11,28–31]. ICG’s high tissue penetration and rapid lymphatic circulation time may promote the detection of non‐sentinel lymph nodes with lesser florescence. Our study design did not have a comparative control group that would allow us to test this directly, however, six patients (11.5%) had an additional lymph node removed that would otherwise have not been identified by traditional techniques. Establishment of a signal‐to‐background threshold, similar to Geiger count thresholds, may be helpful. Since ICG is a small particle tracer that travels quickly through lymphatics, secondary (non‐sentinel) lymph nodes may be identified and unnecessarily removed as sentinel nodes.
TABLE III. Univariate Logistic Regression for Association With Failure of Indocyanine Green to Detect a Sentinel Lymph Node Odds Ratio (95% Confidence Interval) Age Male gender Body Mass Index Histology: Non superficial spreading melanoma Breslow depth > 1 mm Location: trunk LN Metastasis LN Location: inguinal Technetium‐99m positive Isosulfan Blue positive
1.01 1.64 0.88 0.72 1.60 0.82 1.29 1.31
(0.96–1.05) (0.40–6.65) (0.77–1.01) (0.14–3.79)
(0.31–8.35) (0.20–3.34) (0.26–6.35) (0.24–7.10) N/A 2.79 (0.64–12.10)
Indocyanine Green for SLN Biopsy This may especially be problematic in patients with multiple lymph node basins as the ICG tracer may have migrated after the first SLN dissection. ICG was well tolerated in our patients with no immediate or short term complications related to administration as reported by others [32]. Intradermal ICG is easy to administer, similar to blue dye injections, and the SPY EliteTM system is fairly intuitive to use. It is unclear whether a threshold number of procedures are needed to obtain competency. We, as others, did not find evidence of a learning curve throughout the one year study period [12]. Perhaps with ongoing experience, the success rate with ICG would continue to improve. The main limitation of the current study is its single institution and retrospective design. In addition, our analysis is limited to melanoma of the trunk and extremities. Previous studies have investigated the use of NIR fluorescence in melanoma of the head and neck, showing promise [10]. Future work should include randomized controlled trials comparing the use of ICG to standard methods of SLN mapping with outcome measures, such as number of lymph nodes excised and need for handheld Geiger probe, clearly defined.
CONCLUSIONS NIR fluorescent lymphangiography using ICG safely facilitates SLN identification for patients with cutaneous melanoma of the trunk and extremities. When ICG and TSC are used in combination, ISB offers no additional advantage and may be safely omitted.
ACKNOWLEDGMENT We would like to thank Shannon Meyer for her invaluable assistance in the course of this study.
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