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Sentinel Nodes J.R.Buscombe RFH
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Sentinel Nodes Uses the Morton principle of logical lymph drainage from a tumour Methods use include blue dye and radiotracers Combination of 2 may be best Pioneers in breast Morton/Krag/Guilianno USA (EIO, Italy and AMC, Netherlands) In Melanoma-Morton/Guilianno May replace high morbidity axillary clearance
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Sentinel nodes Tumour 2nd and 3rd order nodes Sentinel (1st node)
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Morbidity of Axillary Surgery
Seroma 50% Lymphoedema 10-30% Severe ICBN neuralgia 5% Shoulder-girdle dysfunction 20% Numbness 80% Lymphoedema rates: RT alone : 10% Sampling: 10% Level III clearance 30% Surgery + RT: 70%
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Sentinel nodes
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Sentinel nodes Methods all similar
Depends on injecting radiotracer in or near cancer Using gamma camera and probing to track tracer through lymphatics Intra-operative probe to remove the sentinel node
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Sentinel node Controversies Who to inject Where to inject
How much to inject How much activity to inject What colloid to use When to operate Training
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Injection technique is standardised: Intradermal Periareolar,tumour quadrant
Different injection sites (intradermal, subareolar and peritumoural) have advantages and disadvantages depending on the desired effect on the pattern and kinetics of lymphatic drainage. NEWSTART is designed to minimise visualisation of IMN Activity injected will depend on the time from injection to surgery Massage post injection
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Size matters The size of a colloid may have an effect on its transit
However not simple as charge and flexibility of the colloid may change transit Remember the lymph system is a complex transit system and may be affected by many factors
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What size then? No perfect colloid for sentinel node scintigraphy
All colloids designed for another job Nanocol – infection imaging Albures – lymphoscintigraphy MAA – lung scanning
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How colloids made? Normally made from albumin
Man Cow Pig Often heated to form clusters May be spun Can vary in size by factor of 10
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Types of colloids used Tc-99m antimony colloid
3-30 nm Tc-99m sulphur colloid-filtered nm Tc-99m HSA-nanocoll 4-100 nm Tc-99m HAS Albures nm Tc-99m MAA >5000nm
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Optimal colloids Will pass to sentinel node and stay there
Smaller colloid will pass through so multiple nodes seen May clear form sentinel node totally so no counts if >4 hours post injection Frequent imaging helps
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What to inject?
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Intra-operative probing
If using small colloids should be done within 4 hours post injection Larger colloids can be done at 24 hours During imaging mark site of sentinel nodes on the skin in two planes External probing can help pre-op
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Intra-operative probing
About 20 different probe types available Different crystals have different sensitivities Most use CdTe, CsI, NaI BiGeO crystals Needs good collimation to prevent activity passing through the side of the probe
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Probing the node
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Intra-operative probing
Inject blue dye at site of tumour just before operation Use blue dye to help find lymphatics Probe along blue dye tract until signal high Remove node send to histology
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Use of blue dye and radio-tracer
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Probe box
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Sentinel nodes Results Pagenelii’s group from Milan
Over 400 patients 98% successful identification of sentinel node Caution from USA (Krag et al) High variability in results surgeon to surgeon (64-100% PPV) Issues of training/audit ALMANAC
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Potential problems Injection incorrect (intradermal)
Breast not massaged Colloid too small/big (manafcturer’s QC) Probing performed badly so node missed Poor collimation means signal swamped Problems with histology etc
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Areas where problems seen in breast cancer
Multifocal/centric tumours (maybe helped by nipple injection) Find this disease with Tc-99m MIBI or MRI Previous surgery around primary Breast irradiation Neo-adjuvant chemotherapy Vascular invasion of tumour
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MRI and Tc-99m MIBI
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Sentinel nodes Can it replace axillary clearance as a staging procedure Need to await phase III trials Patients with T1N0 randomised to ax clearance or sent node Who has better morbidity Any difference in survival Need 5 year follow-up
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Results in Melanoma Published by Morton’s group
Reviewed results of 1900 patients having sentinel node for melanoma All had blue dye and colloid All had Breslow thickness greater than 5mm Recurrence rate measured at a mean of 7 years
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Does sentinel node effect outcomes?
Morton’s review Ann Sur Onocol 2000 1900 patients Sentinel node vs blind wide local excision
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How is melanoma sentinel node different?
Melanoma can occur anywhere Drainage much more variable May drain to more than one set of nodes Head and neck Trunk Different speeds of flow Leg minutes Head minutes
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Method-melanoma Normally done after removal of primary
Aim to identify correct block of lymph nodes to disect Inject at 4 pints around scar of excision Inject at least 5mm away from the scar Massage gently Image draining nodes Calf-groin Back Both inguinals and both upper thorax
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Injection for melanoma
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Melanoma-methods Mark any node found
Use shadow gram and laterals and obliques help surgeon identify node In op use blue dye to find lymphatics and direct surgeon to node Surgeon the removes sentinel and associated nodes
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Melanoma in the leg In leg passage fast up into groin, as the groin nodes are the draining nodes the sentinel node is in the groin The popliteal nodes are ignored
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Melanoma on crest of head covered by lead; note bilateral sentinel nodes
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Other sites in which sentinel node can be used
Melanoma – all patients as variable drainage Penis Tongue Head and neck Vulva Colon!
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NEW START Sentinel Lymph Node (SLN) training programme
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NEW START SLN training programme 2004-2006
Joint Project Department of Education: Royal College of Surgeons of England Cardiff University Wales Supported by DoH, National Assembly in Wales GE Healthcare BNMS
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NEW START SLN training programme
National Training Programme Standardised methodology and training materials Focus on multidiscipline team – Surgery, Nuclear medicine/physics, Radiology, Theatre nurses, Pathology, etc Experienced validated training teams Unique workplace training and mentorship Quality assured Centrally audited and validated (anonymised data collection)
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NEW START SLN training programme: Standardized National Training
World wide trials* have shown ad-hoc adoption of SLNB, with little formal training, reduces the accuracy of SLN identification for the first 50 procedures. Evidence from the UK ALMANAC trial demonstrates that structured training shortens the learning curve to less than 10 procedures. * Cox et al: Annals Surg. Oncol.1999, vol l6, page 6
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NEW START SLN training programme Overview
3 training phases 1.Theory Day In House Training Validation Stand alone SLNB Theory Skills SLNB + standard procedure Projected Time frame:18-24 months
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Conclusion Sentinel node study established in melanoma and breast
Useful in reducing mutilating surgery Simple to learn technique but needs good colloid and good probe Can be combined with other NM test such as PET and scintimammography All members of the team important
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