This is a prospective within-patient clinical study to assess the accuracy of ICG SLNB compared to standard dual-tracer SLNB in breast cancer patients treated with neoadjuvant chemotherapy. For SLNB, triple localization of the sentinel lymph nodes using blue dye, Tc-99m and ICG will be utilized in each patient.

During sentinel lymph node biopsy the surgeon will inject a volume of 0.1ml divided into 2 doses (0.05ml each) of 2.5mg/mL ICG into the periareolar dermis of the involved breast. Technetium and blue dye will also be administered as per standard of care. The surgeon will assess the axilla with the the SPY-PHI near infrared imaging system to identify and remove ICG-fluorescent nodes; Any other sentinel lymph nodes identified will also be removed as per standard of care. If there is no progression of ICG towards the axilla, or if no ICG sentinel lymph node can be identified, an alternate injection technique involving peritumoural injection at 2-3 locations near the cancer site in the subcutaneous or dermal space of 0.05ml will be utilized.

Proportion of lymph nodes identified with ICG compared to the proportion of lymph nodes identified with dual tracer (blue dye/Tc-99m gamma probe)

Surgical intra-operative and post-operative complications will be collected to determine safety outcomes. All intra-operative complications will be graded using the ClassIntra classification. All post-operative complications (up to 30 days post-surgical treatment) will be graded using the Clavien-Dindo classification. Treatment-related adverse events will be assessed by CTCAE v5.0.

We will quantify all direct costs associated with implementation of ICG guided SLNB in breast cancer and annual operational costs; these will enable a comparison to cost of the current standard SLNB with Tc-99m and blue dye, including nuclear medicine infrastructure, technicians, and additional health care visits.