p16INK4a expression was found in a majority of triple-negative breast carcinomas (TNBC) (85.71%, 12/14) and HER2-enriched carcinomas (68.75%, 11/16), whereas it was less frequent in Luminal-B type tumors (15.38%, 4/26) and was not found in Luminal-A tumor (0.00%, 0/28) or in Luminal-HER2-Positive tumors (0.00%, 0/8). The gene discussed is CDKN2A; the disease is neoplasm.