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

#Arrangoiz #BreastSurgeon #CancerSurgeon #SurgicalOncologist #Surgeon #Teacher #BreastCancer #BreastDiseases #AxillaryDissection #BreastSurgery #MountSinaiMedicalCenter #MSMC #Miami #Mexico

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