Lymphoscintigraphy and Single-Photon Emission Computed Tomography (SPECT)/CT to Determine Need for Second Sentinel Lymph Node Biopsy for Breast Cancer Recurrence Following Ipsilateral Breast/Axillary Surgery.

BACKGROUND For patients with cN0 breast cancer, sentinel node biopsy (SNB) is performed to confirm metastasis. When cancer recurs after a breast/axillary surgery, performing a second SNB is debatable in terms of its accuracy and significance. However, SNB is often performed because it is less invasive and can provide significant information. This report describes our experience of performing lymphoscintigraphy and single-photon emission computed tomography (SPECT)/CT to determine whether SNB is informative or not in patients who develop ipsilateral breast tumor recurrence (IBTR) following a breast/axillary surgery. CASE REPORT We included 9 patients with breast cancer and a history of ipsilateral breast/axillary surgery who underwent lymphoscintigraphy and SPECT/CT between April 2020 and July 2023. For lymphoscintigraphy, 20-25 MBq of 99mTc-phytate was injected subcutaneously in the areola, and planar images and SPECT/CT were taken at 15 min and 3 h after the injection. In lymphoscintigraphy, radioisotope accumulation was detected in 2 patients at 15 min and 8 patients at 3 h; it was not detected in 1 patient. The accumulation site was only the axilla in 3 patients; other sites including the axilla in 3, and sites outside the axilla in 2. CONCLUSIONS When a patient who previously underwent breast/axillary surgery develops IBTR, the initial surgery may have altered the lymphatic flow. The lymphatic flow varied between the contralateral or ipsilateral internal mammary lymph nodes, contralateral axilla, multidirectional flow, and the axilla alone. Lymphoscintigraphy and SPECT/CT may be useful for early determination of the need for another SNB.