In the experimental group, 1 ml (2.5 mg) indocyanine green (ICG) and methylene blue (MB) was intradermally injected into the internal bicipital sulcus of ipsilateral arm. During axillary dissection, the identified arm sentinel nodes were carefully injected with 0.1 ml methylene blue (MB) using a 1-cc syringe with a 32-gauge needle. MB could then flow from the nodes along several lymphatic channels toward the infraclavicular nodes. Subsequent-echelon nodes and lymphatics were identified. Sentinel lymph nodes (SLNs) were removed after the identification of the arm sentinel nodes and the procedure of MB injection. When patients harbored positive SLNs, axillary lymph node dissection (ALND) was performed subsequently. All discernible arm lymphatics and lymph nodes were preserved, except that gross arm lymph nodes (major axis larger than 10 mm or node firm on palpation) were sent for immediate partial frozen section (pFS) to determine their resection during ALND.

In the control group (no intervention), ALND was performed with complete resection of at least Berg's levels I and II. Resection of level III was performed only in cases with gross disease in level II and/or III

Indocyanine green was utilized to identify arm sentinel nodes, and 0.1 ml MB was injected into the arm sentinel nodes to reveal the subsequent-echelon nodes and lymphatics. Gross arm lymph nodes were examined by intraoperative partial frozen section and were removed if positive.

A difference in volume between the arms < 10% was defined as lymphedema.

Locoregional recurrence included local recurrence and regional recurrence. Local recurrence was defined as chest wall recurrence of breast cancer, and regional recurrence was defined as the axilla recurrence of breast cancer.