2 IntroductionThe presence or absence of lymph node metastases remains the most powerful predictor of outcome in malignant melanoma.
3 Rationale Sentinelle - ‘to guard over’ or ‘vigilance’ The node(s) that has the highest risk of harbouring micrometastatic disease.
4 History of the procedure First described more than 50 years ago and used to stage carcinoma of the penis.Proposed by Morton as an alternative to elective lymph node dissection in melanoma, in 1992.
5 Objective of the procedure To identify the 20-25% of patients who present with clinically occult regional disease.To minimise the morbidity associated with elective lymphadenectomy by identifying those patients most likely to benefit.Identifies those patients who may benefit from post-operative adjuvant therapy.Provides a means to stratify patients for randomised clinical trials.
6 IndicationsTypically recommended for patients in whom the estimated risk of lymph node metastases is at least 10%.
7 AJCC recommendationsRecommended as a staging procedure in patients whom the information would be useful for planning subsequent treatment and follow–up.Specifically should be discussed with and recommended for those otherwise fit patients with T2, T3 and T4 disease, and clinically uninvolved lymph nodes, and selectively recommended for patients with T1b melanomas.
8 Contraindications Palpable lymph node. Presence of satellite lesions or in transit metastasis.Allergy to dye or latex.Disruption of lymphatic drainage, i.e. prior wide excision.
9 The Head and Neck Drainage patterns variable and unpredictable. Radioactive signal from the primary tumour may obscure that from the SLN in nearby nodal basin.Localisation rate less than 95%.Increased surgical morbidity.
10 Nuclear MedicinePatients undergo pre- operative lymphoscintigraphy and injection of radioactive isotope around the primary melanoma site or excisional biopsy scar.
11 Identifying the Sentinel Node Gamma probe directs the surgeon to the area of greatest radioactivity.Blue dye is used to visualise lymphatics to help decrease the dissection needed to detect the SLN.
12 ‘N’ marks the spot...The location of the highest radioisotope uptake is marked to indicate the presence of the sentinel node(s).
13 In theatre0.5 – 1ml of 1% isosulfan blue is injected intradermally around the intact tumour or biopsy site.The blue dye travels to the SLN within 5-15 mins.
14 Wide ExcisionA wide local excision of the primary tumour site is performed.
15 A hand held gamma probe is used to identify hot spots in the identified regional lymph node basin or basins.A small incision is made over the hot spot.
16 A blue stained afferent lymphatic vessel is sought and a combination of this visual cue and the gamma probe lead to the identification of a hot and or blue sentinel node(s)
17 A SLN is defined as one that localised blue dye and/or concentrated radiolabelled colloid within a regional nodal basin.
18 Postoperative care Discharged the day of, or the day after surgery. Outpatient appointment 2 weeks to discuss results.
19 Complications Overall rate less than 5% Failure to identify node Allergic reactionBleedingInfection (1%)Lymphoedema (<2%)Seroma (2%)False negative result (4.7-8%)
20 Locoregional recurrence 1-6% risk of isolated nodal relapse in the mapped nodal basin after negative SLNBx (follow-up months in 14 published series).
21 Completion regional lymphadenectomy Offered to all patients with positive sentinel node result.No method to reliably predict those patients who will have residual metastatic disease in other non-sentinel nodes.70-80% have no further disease identified.
22 Outcome and PrognosisSentinel node status has prognostic significance with 90% 5 year survival for SLN-negative patients versus 72% for SLN-positive patients.Sentinel lymph node biopsy has not been shown to increase the risk of developing in-transit disease.
23 Trial Data – MSLT 1No overall significant survival benefit for patients randomised to wide local excision and SLNBx with early lymph node dissection, versus observation (86% vs. 87% at 5 years).Disease free survival was significantly better for patients undergoing SLNBx (78% vs. 73% at 5 years).
24 The Future...RT-PCR to improve sensitivity of detecting occult metastatic disease.MSLT 2 - Completion lymphadenectomy versus follow-up only following a positive sentinel node.
25 ConclusionSentinel lymph node status has been shown to be a powerful indicator of prognosis in patients with melanoma.SLNBx identifies patients who may benefit from adjuvant therapy and stratifies patients into more homogenous groups for inclusion in clinical trials.Improved disease free survival.