MIB1 and breast cancer: By contrast, in patients diagnosed with invasive BC at low proliferation rate (MIB1 < 20%), only cT4 (1 patient, 1.8% in 2019 versus 7 patients, 7.8% in 2020; P = 0.0238) and stage III tumors (2 patients, 1.8% in 2019 versus 10 patients, 11.1% in 2020; P = 0.0064) were significantly increased, whereas node-positive BC remained stable (P = 1).