Takada K, Kashiwagi S, Asano Y, et al. - Given a greater probability of lymph node metastasis in early-stage breast cancer with lower tumor-infiltrating lymphocyte (TIL) density, researchers examined the link between TILs and lymph node metastasis in cT1 breast cancer patients receiving surgery. They also determined whether TILs are beneficial in predicting sentinel lymph node metastasis (SLNM) in cT1N0M0 breast cancer. They examined 332 cases of breast cancer managed with surgery as the first-line treatment following preoperative diagnosis of cT1. A median of 2 (range, 1–8) SLNs (sentinel lymph nodes) were pathologically assessed for SLN biopsy. Experts observed 60 cases (19.4%) of SLNM (macrometastasis: 46, micrometastasis: 16). In breast cancers with tumor diameter > 10 mm, a significantly greater metastasis was reported compared with those with diameter ≤ 10 mm. Overall, in cT1 breast cancer, lymph node metastasis was found to be correlated with tumor immune-microenvironment. Also, a possible role of TIL density was suggested as a predictor of SLNM in breast cancer without lymph node metastasis on preoperative imaging.