HDAC4 and serous adenocarcinoma: FIGO stage IV tumors were more frequently negative for HDAC-4 (35.3%) compared with the tumors with lower FIGO stages (I–III, 16.2%), which was a relationship of marginal significance in the entire cohort (Chi-square test, p = 0.07), but was proven to be significant in tumors with serous histology (borderline and carcinomas, N = 80, p = 0.05) and especially in serous carcinomas (N = 74, p = 0.045).