['Several radioactive agents are used for sentinel lymph node biopsy (SLNB) in breast cancer, but we are still unsure which of these is best. We retrospectively compared the effectiveness of two radioactive agents, 99mTc-phytate and 99mTc-human serum albumin (HSA), when used in combination with blue dye.', 'A consecutive series of 533 clinically node-negative patients with a collective 539 breast carcinomas were divided into two groups for treatment with SLNB. The HSA-group consisted of 264 patients (with a collective 266 breast cancers) and the P-group consisted of 269 patients (with a collective 273 breast cancers) treated with 99mTc-HSA and 99mTc-phytate, respectively, in combination with blue dye. We analyzed the identification and radioactivity of SLNs in the two groups.', 'The identification rate of SLN was significantly higher in the P-group than in the HSA-group. The same results were produced by analysis using the radioactive agent alone, but not by using the blue dye alone. Most importantly, the highest radioactivity of SLNs per case was more than five times higher in the P-group than in the HSA-group, and this difference was significant.'] Is 99mTc-phytate better than 99mTc-human serum albumin as a radioactive tracer for sentinel lymph node biopsy in breast cancer?