Upon histological analysis, staining for MLH1, MSH2, MSH6, PMS2, pAKT, and HER2 was similar in both samples, but in the 2017 tumor, there was 60% increased staining for RRM1 and 20% increased staining for ERCC1, which changed the classification from low to high staining for ERCC1. The gene discussed is ERCC1; the disease is neoplasm.