SENTINEL LYMPH NODE BIOPSY – Technique and Indications

• The lymph node that is the most likely to harbor metastatic disease:
  • Is the sentinel lymph node
• In a landmark study published in 1994:
  • A vital blue dye:
    • Was used to identify the first node in the lymphatic chain to harbor metastatic tumor
  • An axillary dissection was then completed:
    • The pathologists evaluated the sentinel lymph node separately from the remaining axillary contents:
      • The sentinel node was identified with a specificity of 96% in 174 consecutive patients with various stages of breast cancer
• As the sentinel node technique was further explored:
  • Additional studies demonstrated that SLNB could be reliably preformed using:
    • Radiolabeled colloid
    • Vital blue dye:
      • Methylene blue
      • Isosulfan blue
      • Blue patent
    • Both techniques:
      • Radiolabeled colloid and vital blue dye
• The American Society of Clinical Oncology (ASCO):
  • 2014 Sentinel Lymph Node Biopsy Early-Stage Breast Cancer Update:
    • Evaluated the performance of SLNB and reported that:
      • False negative rates of the procedure ranged from:
        • 4.6% to 16.7%
      • An overall accuracy of:
        • 93% to 97.6%
    • Factors that increase the false negative rate of SLNB are:
      • Obesity
      • Tumor location
      • Failure to localize a lymph node on lymphoscintigraphy
      • Patient age
      • Surgeon experience
• When radiolabeled sulfur colloid is used:
  • 0.4 mCi to 2 mCi of technetium-99m (99mTc)-labeled particles:
    • Measuring 50 to 200 nm in diameter are injected into the breast:
      • From 30 minutes to 24 hours before SLNB
    • Higher doses:
      • Are often used if the patient is injected the day prior to the operation
  • After injection:
    • The area is massaged gently for approximately 5 minutes:
      • To improve the lymphatic drainage
  • Patients may undergo static scintigraphy images:
    • To aid localization
• In the operating room:
  • A gamma probe is used to identify the radioactive node
    • “Hot” nodes:
      • Nodes that qualify as sentinel lymph nodes are those that have:
        • Counts greater than 10% of the ex vivo counts of the most radioactive lymph node
• Using a threshold of more than 10% of the hottest node:
  • Has been validated and correctly identifies:
    • 98% of sentinel lymph nodes
• 99mTc-labeled sulfur colloid and lymphoscintigraphy:
  • Can identify alternate lymphatic drainage:
    • And are particularly useful in patients with previous axillary operations
• Most surgeons find the use of both radioisotope and blue dye to be more successful than one method alone:
  • However, either may be used alone in experienced hands
• If vital blue dye is used:
  • 3 ml to 5 mL of solution is injected:
    • Followed by at least 5 minutes of massage is used:
      • To improve lymphatic drainage
• With either technique:
  • A transverse incision is then made:
    • Along the inferior margin of the hair-bearing region of the axilla
  • Blunt and sharp dissection:
    • Is used to identify a lymphatic track or blue-stained or “hot” node
  • Following removal of the sentinel lymph node:
    • The surgeon should palpate the axilla for any additional suspicious nodes and remove these as well
  • Although most patients have one sentinel lymph node:
    • Multiple nodes may be identified and should be removed
  • Care should be taken to remove only the targeted lymph node or nodes:
    • Separating them carefully from investing axillary fat:
      • As excessive dissection and tissue removal:
        • May increase rates of postprocedure seroma or lymphedema remove these as well
• Complications following SLNB are less frequent than complications following ALND:
  • Especially with respect to:
    • Lymphedema, sensory loss, and mobility
• Patients following SLNB:
  • Report improved quality of life and a more rapid return to work:
    • However, the International Cooperative Group Trial:
      • Reported lymphedema and seroma in:
        • 7% of patients treated with SLNB
      • Wound infection and hematoma rates:
        • Were both 1%
      • Shoulder or arm pain and decreased abduction are:
        • Also occasionally seen with SLNB.
• Both methylene blue and 1% isosulfan blue dye:
  • Are commonly used to identify sentinel lymph nodes:
    • Isosulfan blue has a documented risk of allergic reaction, resulting in:
      • Rash, urticaria, and hypotension:
        • In as many as 3% of patients
      • Anaphylaxis:
        • In less than 1%
  • Although methylene blue is less costly and has a lower risk of anaphylaxis:
    • It is associated with skin necrosis in up to 10% of patients:
      • When injected intradermally or subcutaneously
    • For this reason, it should be diluted 1:2 in saline:
      • And an intradermal injection should be avoided
  • Multiple studies have tried to prove the superiority of one or other of these dyes:
    • They appear equivalent
• Debate remains about the location of injection:
  • Peritumoral, subareolar, subdermal, and intradermal injection sites have all been used
  • Studies have shown that there is little difference between areolar injections and peritumoral injections:
    • But a randomized controlled trial:
      • Suggested that areolar intradermal injections:
        • Have the highest rates of localization and decreased harvest time of the first sentinel lymph node
  • In tumors that are large and in the upper outer quadrant of the breast:
    • Peritumoral injection is probably superior
  • In patients who undergo nipple-sparing mastectomy:
    • Subareolar injection should be avoided
  • Skin tattooing:
    • Can occur with intradermal injection
• Patients with early-stage invasive breast cancer (clinically T1 and T2):
  • Who do not have clinically positive lymph nodes (cN0):
    • Should undergo SLNB
• The ASCO reviewed the literature and created guidelines for the use of SLNB:
  • The current ASCO guidelines for SLNB are displayed in the second table
• SLNB is widely applicable:
  • But there are some circumstances:
    • In which it is contraindicated
    • And others in which its utility is questionable
  • Given the dermal and pervasive lymphatic involvement in inflammatory carcinoma:
    • An ALND should be performed in patients with inflammatory cancer:
      • These patients have lymphatic vessels largely obstructed by tumor emboli:
        • Making sentinel node localization unreliable with high false negative rates:
          • Even after neoadjuvant chemotherapy (NAC)
  • Patients with large or locally advanced breast cancers (clinically T3 / T4):
    • Have historically:
      • Not been offered SLNB
    • Small case series have shown a large variability in:
      • The accuracy (85% to 98%) and a false negative rate (3% to 18%) of SLNB for patients with large tumors:
        • And these patients made up a small group in large, randomized sentinel lymph node clinical trials
    • Clinically node-negative patients with large tumors:
      • Also have high rates of positive SLNB as well as additional involved nonsentinel lymph nodes:
        • Ranging from 40% to 80%
      • Although many practitioners perform SLNB for patients with clinically T3 tumors;
        • Current ASCO guidelines argue that there is still insufficient evidence to support the practice

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