Sentinel lymph node identification with radiopharmaceuticals in patients with breast cancer: a comparison of 99mTc-tin colloid and 99mTc-phytate efficiency

Sentinel lymph node biopsy with lymphoscintigraphy has become the standard method for the detection of axillary lymph node metastasis in breast cancer patients. However, there is no standardized radiopharmaceutical. For the detection of axillary lymph node metastasis by lymphoscintigraphy and sentinel node biopsy in patients with breast cancer, we compared the results between subareolar injection of Tc-99m-tin colloid and injection of Tc-99m-phytate. This study included 516 breast cancer patients who underwent surgery between 2001 and 2010. Among the 516 patients, Tc-99m-tin colloid (37-185 MBq) was administered to 412 patients by subareolar injection, and Tc-99m-phytate (37-185 MBq) was injected in 104 patients. Lymphoscintigraphy was performed with the patients in the supine position, and sentinel node identification was performed by hand-held gamma probe during surgery. Among 412 patients with Tc-99m-tin colloid, the sentinel node was identified by lymphoscintigraphy in 364 cases (88.3%) and by a gamma probe in 369 cases (89.6%). Among 104 patients with Tc-99m-phytate, 101 cases (97.1%) were identified by lymphoscintigraphy and 101 cases (97.1%) were identified by a gamma probe. The identification rates by lymphoscintigraphy and gamma probe were superior with Tc-99m-phytate, as compared with Tc-99m-tin colloid, with a statistically significant difference (P < 0.05 for both methods). Tc-99m-phytate is a better choice than Tc-99m-tin colloid for identification of the sentinel node in breast cancer patients.