E1780. Accuracy of Ultrasound Guided Tattooing of Biopsy Proven Positive Lymph Nodes Before Neoadjuvant Chemotherapy in Breast Cancer Patients
  1. Africa Pineiro; Instituto Alexander Fleming
  2. Alejandra Varela; Instituto Alexander Fleming
  3. Agostina Peralta; Instituto Alexander Fleming
  4. Catherine Ulloa; No Affiliation
  5. Federico Colo; Instituto Alexander Fleming
  6. Mora Amat; Instituto Alexander Fleming
  7. Daniel Mysler; Instituto Alexander Fleming
The objective is to determine the identification rate of tattooed lymph nodes with activated charcoal suspension during axillary surgery in patients with positive lymph nodes before neoadjuvant chemotherapy (NAC). The secondary objective is to establish the rate of concordance between the marked lymph nodes and the sentinel lymph nodes in patients undergoing sentinel lymph node biopsy.

Materials and Methods:
We conducted a retrospective study from 2016 - 2022, including 82 patients with breast cancer (T1 –T3) and positive lymph nodes (N1 - N2). Axillary ultrasound was performed before NAC. For lymph nodes with abnormal findings, an ultrasound core-guided biopsy was performed. If positive cytology during biopsy was confirmed, the sampled lymph node was marked with a sterile charcoal suspension. Under ultrasound guidance 0-2 – 0-3 cc of sterile carbon suspension was placed in the perinodal fat. Patients underwent neoadjuvant chemotherapy and posterior axillary surgery. After surgery, the rate of detection of the tattooed lymph node was calculated as well as the rate of concordance between the inked lymph node and the sentinel lymph in patients who underwent sentinel lymph node biopsy.

The tattooed lymph node was successfully identified during surgery in 60 patients. The detection rate during axillary surgery was of 73%. In 22 (27%) patients, charcoal suspension was not identified. Of the 60 patients whom charcoal suspension was identified, 56 (93%) had sentinel node biopsy and 4 (7%) had axillary lymph node dissection. Concordance between the sentinel lymph node and the tattooed lymph node was observed in 46 patients (82 %.).

The SENTINA study concluded that for cN1 breast cancer patients who underwent sentinel lymph node biopsy after neoadjuvant chemotherapy, the false negative rate (FNR) was above 10%. The ACOSOG Z1071 study showed that clipping the positive lymph node before surgery reduces significantly the FNR of this technique. The ultrasound guided use of charcoal suspension for tattooing positive nodes during the biopsy is an effective and minimal invasive technique that has shown to have a high identification rate during axillary surgery and a high concordance rate with the sentinel lymph nodes in patients undergoing sentinel lymph node biopsy. Axillary lymph node tattooing with sterile charcoal suspension is a viable, low cost and precise method especially useful in low resources settings. This technique avoids placing a clip and posteriorly marking it with wire or radioactive seed previous to surgery, reducing the number of procedures, costs and time.