Strong p16 expression was tightly linked to adverse tumor features, including histopathological grade (p < 0.0001), advanced tumor stage (p = 0.0003), and hormone receptor (ER/PR) negativity (p < 0.0001 each) in all breast cancers and in the largest subset of cancers of No Special Type (NST; p ≤ 0.0010). The gene discussed is ESR1; the disease is breast cancer.