Activating mutations in KRAS and in one of its downstream mediators, BRAF, have been identified in a variety of human cancers. To determine the role of mutations in BRAF and KRAS in ovarian carcinoma, we analyzed both genes for three common mutations (at codon 599 of BRAF and codons 12 and 13 of KRAS). Mutations in either codon 599 of BRAF or codons 12 and 13 of KRAS occurred in 15 of 22 (68%) invasive micropapillary serous carcinomas (MPSCs; low-grade tumors) and in 31 of 51 (61%) serous borderline tumors (precursor lesions to invasive MPSCs). None of the tumors contained a mutation in both BRAF and KRAS. In contrast, none of the 72 conventional aggressive high-grade serous carcinomas analyzed contained the BRAF codon 599 mutation or either of the two KRAS mutations. The apparent restriction of these BRAF and KRAS mutations to low-grade serous ovarian carcinoma and its precursors suggests that low-grade and high-grade ovarian serous carcinomas develop through independent pathways.

The clonal relationship between ovarian high‐grade serous carcinoma (HGSC) and its presumed precursor lesion, serous tubal intraepithelial carcinoma (STIC), has been reported. However, when analyzing patients with concurrent ovarian carcinoma and tubal lesion, the extensive carcinoma tissues present at diagnosis may have effaced the natural habitat of precursor clone(s), obscuring tumor clonal evolutionary history, or may have disseminated to anatomically adjacent fimbriae ends, masquerading as precursor lesions. To circumvent these limitations, we analyzed the genomic landscape of incidental tubal precursor lesions including p53 signature, dormant STIC or serous tubal intraepithelial lesion (STIL) and proliferative STIC in women without ovarian carcinoma or any cancer diagnosis using whole‐exome sequencing and amplicon sequencing. In three of the four cancer‐free women with multiple discrete tubal lesions we observed non‐identical TP53 mutations between precursor lesions from the same individual. In one of the four women with co‐existing ovarian HGSC and tubal precursor lesion we found non‐identical TP53 mutations and a lack of common mutations shared between her precursor lesion and carcinoma. Analyzing the evolutionary history of multiple tubal lesions in the same four patients with concurrent ovarian carcinoma indicated distinct evolution trajectories. Collectively, the results support diverse clonal origins of tubal precursor lesions at the very early stages of tumorigenesis. Mathematical modeling based on lesion‐specific proliferation rates indicated that p53 signature and dormant STIC may take a prolonged time (two decades or more) to develop into STIC, whereas STIC may progress to carcinoma in a much shorter time (6 years). The above findings may have implications for future research aimed at prevention and early detection of ovarian cancer. Copyright © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Purpose: Mitogen-activated protein kinase (MAPK) plays a pivotal role in signal transduction. Activation of MAPK is regulated by upstream kinases including KRAS and BRAF, which are frequently mutated in low-grade ovarian serous carcinoma. This study evaluates the expression of active MAPK in ovarian serous carcinomas, with response to treatment and survival. Experimental Design: Expression of active MAPK was assessed by immunohistochemistry in 207 cases of ovarian serous tumors. Immunoreactivity was correlated with tumor grade, mutational status of KRAS and BRAF, in vitro drug resistance, and clinical outcome. Result: There was a lower frequency of expression of active MAPK in high-grade ovarian serous carcinomas as compared with low-grade serous tumors, including borderline tumors and low-grade serous carcinoma (P < 0.001). Active MAPK was present in all of the 19 low-grade tumors with either KRAS or BRAF mutations as well as in 14 (41%) of 34 tumors with wild-type KRAS and BRAF in both low- and high-grade carcinomas. Expression of active MAPK alone served as a good survival indicator in the 2-year follow-up (P = 0.037) but not in the 5-year follow-up (P = 0.145). However, a combination of expression of active MAPK and in vitro sensitivity of paclitaxel significantly correlated with a better prognosis in 5-year survival rate (P = 0.048) in patients with advanced-stage high-grade serous carcinoma. Conclusions: Active MAPK is more frequently expressed in low-grade than in high-grade ovarian serous carcinoma. Active MAPK serves as a good prognostic marker in patients with high-grade serous carcinomas.

BACKGROUND: This retrospective study compared the nondiagnostic rate for endoscopic ultrasound‐guided (EUS) fine‐needle aspiration (FNA) of pancreatic lesions in 2 settings: 1 with and 1 without on‐site evaluation. METHODS: The authors reviewed 381 consecutive cases and divided them into groups with and without on‐site adequacy evaluation. For the group with on‐site evaluation, cytopathology personnel prepared and evaluated Diff‐Quik–stained direct smears and rinsed the remaining material in CytoLyt solution (Cytyc Corporation, Marlborough, Mass). The group without on‐site evaluation was divided into 2 subgroups: the clinical team either prepared an air‐dried smear for each FNA pass and then rinsed the remaining material in CytoLyt, or the entire sample was rinsed in CytoLyt. The cytologic diagnoses were reviewed and the nondiagnostic rates for each group were calculated. RESULTS: On‐site evaluation was provided for 167 cases with a nondiagnostic rate of 25.8% (43 of 167 cases). On‐site evaluation was not provided for 214 cases with a nondiagnostic rate of 24.3% (52 of 214 cases). The nondiagnostic rate for the subgroup with air‐dried smears prepared by the clinical team was 25.6% (43 of 168 cases) and that for the subgroup with the entire sample rinsed in CytoLyt was 19.6% (9 of 46 cases). There were no significant statistical differences in nondiagnostic rates noted among the different groups or subgroups. CONCLUSIONS: The results of the current study indicate that when experienced operators perform EUS FNA of pancreatic lesions, on‐site adequacy evaluation offers no benefit in reducing the nondiagnostic rate. Optimizing visualization of the sampled material by omitting the preparation of direct smears and rinsing the entire sample in liquid‐based media demonstrated a trend toward improving the diagnostic rate. Cancer (Cancer Cytopathol) 2012. © 2012 American Cancer Society.