Sentinel Lymph Node Biopsy in the Setting of Neoadjuvant Chemotherapy (NAC)

  • Although neoadjuvant chemotherapy (NAC):
    • Can decrease the size of a primary tumor to allow for breast conservation, eliminate nodal metastasis in some patients, and provide prognostic information:
      • The optimal timing of sentinel lymph node biopsy (SLNB) for patients treated with NAC has been controversial
  • Clinical staging of the axilla with SLNB:
    • Is feasible both before and after chemotherapy
  • SLNB prior to NAC:
    • May be a more accurate approach than after NAC
    • Chemotherapy:
      • May alter lymphatic drainage through fibrosis of lymphatic channels:
        • Decreasing the accuracy of SLNB
    • SLNB before NAC has a lower false negative rate and provides more accurate staging:
      • Which could determine radiation fields
    • Unfortunately, SLNB prior to NAC:
      • Requires an additional operation
      • Could delay the initiation of chemotherapy
      • Fails to decrease the rate of ALND
      • It also given by the effect of chemotherapy on axillary metastasis
  • These concerns have led to interest in performing SLNB after NAC
  • Several recent prospective trials have examined the accuracy of SLNB after NAC:
    • The American College of Surgeons Oncology Group (ACOSOG) Z1071:
      • Enrolled women with T0 to T4, N1 to N2 clinical disease:
        • Who underwent neoadjuvant chemotherapy
      • All patients underwent pre-NAC axillary needle biopsy
      • Forty-one percent of patients had a:
        • Pathologic complete response in the axilla
      • After chemotherapy:
        • Patients underwent both SLNB and ALND
      • A sentinel lymph node could not be identified:
        • In 7% of patients
      • The overall false negative rate was 13%:
        • Which did not meet the preset target of 10%
      • The false negative rate was 21% in patients with two or fewer sentinel lymph nodes identified:
        • But dropped to 9.1%:
          • When greater than three sentinel lymph nodes were sampled
    • In the Sentinel Lymph Node Biopsy in Patients with Breast Cancer Before and After Neoadjuvant Chemotherapy (SENTINA) trial:
      • 1,022 patients underwent SLNB before NAC:
        • With a detection rate of 99%
      • For patients who were evaluated after NAC and converted from cN+ to ycN0:
        • The sentinel lymph node detection rate was only 80%:
          • With a false negative rate of 14.2%
      • As seen in ACOSOG Z1071:
        • The false negative rate:
          • Was much higher in patients with only one node removed (24%):
            • Than in those with three or more sentinel nodes removed (7%)
      • The false negative rate was also improved:
        • By the use of radiocolloid and blue dye together:
          • Compared with blue dye alone:
            • False negative rate of 9% versus 16%
    • The Sentinel Node Biopsy following NeoAdjuvant Chemotherapy (SN FNAC) study:
      • Enrolled patients with T0 to T3 with N1 to N2 biopsy-proven breast cancer treated with NAC
      • Following chemotherapy, patients underwent clinical and ultrasound examination followed by SLNB and completion ALND
      • The overall post-NAC SLNB false negative rate was:
        • 8% in 153 patients
      • When only one sentinel lymph node was evaluated:
        • The false negative rate was again unacceptably high:
          • At 20%
  • On the basis of these three trials:
    • Resecting only one sentinel node:
      • Is associated with an unacceptably high false negative rate
    • The false negative rate after NAC may be lowered with the use of:
      • Dual tracers and resecting three or more sentinel nodes
      • Placing clips in positive lymph nodes before chemotherapy:
        • Decreases the false negative rate:
          • If the clipped node is then resected during SLNB
    • The sentinel lymph node identification rate after NAC:
      • Is significantly improved with increased surgeon experience:
        • Suggesting that a learning curve is needed to obtain accurate SLNB after NAC
  • SLNB after NAC:
    • Has the potential to decrease the number of women who receive ALND
  • A study of 288 prospectively identified clinically node-positive patients:
    • Reported that 132 became clinically node negative after NAC
    • The clinically node-negative patients were then eligible for SLNB:
      • 48% had negative sentinel lymph nodes and were able to avoid an ALND
  • Current ASCO recommendations state that:
    • SLNB should be offered to patients who have received preoperative neoadjuvant systemic therapy and have clinically negative lymph nodes:
      • However, no large studies have examined local recurrence rates or survival:
        • When ALND is omitted in patients who convert from node positive to node negative after NAC
      • The safety of avoiding ALND in these patients:
        • Has not been demonstrated
  • The National Surgical Adjuvant Breast and Bowel Project (NSABP) B51 and Alliance A011202 are two sister studies:
    • Examining the role of SLNB, ALND, and nodal radiation in patients who receive NAC
    • The results of these trials will help identify patients who can safely avoid ALND after NAC

#Arrangoiz #BreastSurgeon #BreastExpert #BreastCancer #CancerSurgeon #SurgicalOncologist #MountSinaiMedicalCenter #MSMC #Miami #Mexico #SLNM #SLNB #SentinelLymphNodeBiospy

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