Mutation and expression of the TP53 gene in early stage epithelial ovarian carcinoma

The early natural history of epithelial ovarian carcinoma remains poorly understood. Mutation of the TP53 gene is common in advanced-stage (III-IV) ovarian cancers, but less well described in early stage (I-II) tumors. The purpose of this study was to perform a comprehensive analysis of TP53 mutation and p53 expression status in early stage ovarian carcinomas.

Seventy-three cases of various histologic types, including 46 stage I and 27 stage II tumors, were subjected to direct sequence analysis of the entire TP53 coding region and exon-intron junctions as well as immunohistochemical assessment of p53 expression.

Overall, mutations were identified in 24 of 73 (34%) cases. However, a significant difference in the distribution of mutations among histologic types was observed; TP53 mutations were present in 14 of 21 (67%) serous cancers and 11 of 52 (21%) non-serous cancers (P = 0.0002). Mutations were equally common between stage I and stage II tumors of serous histology. With respect to the correlation between TP53 mutation and p53 immunopositivity, the sensitivity (58%), specificity (71%), positive predictive value (64%), and negative predictive value (83%) were not sufficiently robust to justify use of p53 expression as a surrogate or screen for mutation.

These data indicate that TP53 mutation is common in early stage ovarian carcinomas of serous histology, with a mutation frequency comparable to that reported for advanced-stage tumors, and is therefore likely to occur early in the progression of the most common histologic variant of ovarian carcinoma.