TP53 mutations are common in all subtypes of epithelial ovarian cancer and occur concomitantly with KRAS mutations in the mucinous type.

AIMS

Epithelial ovarian cancer (EOC) can be classified into four major types (serous, endometrioid, clear cell, mucinous). The prevalence of driver gene mutations in the different subtypes is controversial. High-grade serous carcinomas show frequent TP53 mutations, whereas KRAS and BRAF mutations are less common. In non-serous EOC, the relevance of these gene mutations remains to be elucidated.

METHODS

We investigated 142 formalin-fixed, paraffin-embedded EOC, including serous (n=63), endometrioid (n=29), clear cell (n=25), mucinous (n=14), and others (n=11) for mutations in TP53 exons 5-8, KRAS exons 2 and 3, and BRAF exon 15 by pyro-sequencing using the GS Junior 454 platform. The mutational status was correlated with clinicopathological features and patient overall survival.

RESULTS

We identified mutations in the coding region of TP53 in 51.4% (73/142), and of KRAS in 9.9% (14/142) but not of BRAF. TP53 mutations occurred frequently not only in high-grade serous carcinomas (58.7%), but also in mucinous (57%) and clear cell EOC (52%). TP53 mutations were associated with high-grade carcinomas (p=0.014), advanced FIGO stage (p=0.001), intraoperative residual disease >1cm (p=0.004), as well as poor overall survival (p=0.002). KRAS mutations were mainly identified in mucinous EOC (57%) and were concomitantly with TP53 mutations in five mucinous carcinomas (36%).

CONCLUSIONS

TP53 gene driver mutations are a common feature of all advanced ovarian cancer subtypes, whereas BRAF mutations seem to be a rare event in EOC. KRAS mutations with synchronous TP53 mutations occur predominantly in low-grade mucinous carcinomas, suggesting a specific molecular background of this ovarian cancer type.