Gad Singer

Patterns of p53 mutations separate ovarian serous borderline tumors and low- and high-grade carcinomas and provide support for a new model of ovarian carcinogenesis: a mutational analysis with immunohistochemical correlation.

The infrequent association of serous borderline tumors (SBTs) with invasive serous carcinoma has led to the view that SBTs are unrelated to invasive serous carcinoma. Nonetheless, mortality associated with SBTs is generally attributed to malignant transformation, and traditionally these tumors have been designated as “carcinomas of low malignant potential.” Previous immunohistochemical studies evaluating p53 expression and molecular genetic studies evaluating mutational status have reported that p53 overexpression and mutations are infrequent in SBTs and occur in as many as 50% to 80% of invasive serous carcinomas. The different methodologies for determining p53 status and the failure to correlate the findings with tumor grade make these studies difficult to interpret. The current study was undertaken to overcome these deficiencies and to reconcile the relationship of SBTs to invasive serous carcinoma by performing a morphologic, immunohistochemical, and molecular genetic analysis comparing SBTs with low- and high-grade serous carcinoma. The molecular genetic analysis used a highly stringent, carefully designed nucleotide-sequencing method. A total of 96 sporadic serous tumors including 25 SBTs (11 atypical proliferative serous tumors and 14 intraepithelial low-grade serous carcinomas [noninvasive micropapillary serous carcinomas, MPSCs]), 12 low-grade serous carcinomas (invasive MPSCs), and 59 high-grade serous carcinomas were analyzed for their p53 mutational status of exons 5 to 9. Functional mutations, defined as mutations resulting in the alteration of the structure of the encoded protein, were detected in 30 of 59 (50.8%) high-grade serous carcinomas and 1 (8.3%) of 12 low-grade invasive serous carcinomas compared with 2 (8%) of 25 SBTs, both of these in intraepithelial low-grade serous carcinomas (noninvasive MPSCs). The similar frequency of p53 mutations in SBTs and low-grade invasive serous carcinomas in contrast to the significantly higher frequency of p53 mutations in high-grade serous carcinomas (P < 0.0005) suggests a common lineage for SBTs and low-grade invasive serous carcinomas and supports the view that SBTs are unrelated to the usual type of invasive serous carcinoma, which is a high-grade neoplasm. Mutational status was also correlated with p53 immunoreactivity. Although p53 immunoreactivity is generally higher in those specimens containing mutant p53, immunostaining is neither sufficiently specific nor sensitive enough to predict p53 mutations. The molecular genetic findings confirm our hypothesis of dual pathways of serous carcinogenesis based on previous analyses of KRAS and BRAF mutations on the same set of cases in which KRAS and BRAF mutations were found in 60% of SBTs and low-grade serous carcinoma but not in high-grade serous carcinomas. Based on these studies, we have proposed a model of serous carcinogenesis in which SBTs are the precursors of low-grade serous carcinomas whereas the usual type of invasive serous carcinoma is a high-grade neoplasm that develops “de novo” from in situ alterations in epithelial inclusion cysts.

Diverse Tumorigenic Pathways in Ovarian Serous Carcinoma

This study was undertaken to analyze genetic alterations in 108 sporadic serous ovarian neoplasms to elucidate ovarian serous carcinogenesis. Our results demonstrate that K-ras mutations occur in approximately 50% of serous borderline tumors (SBTs), non-invasive micropapillary serous carcinomas (MPSCs), and invasive micropapillary serous carcinomas, which represent a morphological continuum of tumor progression. Moreover, progressive increase in the degree of allelic imbalance of chromosomes 1p, 5q, 8p, 18q, 22q, and Xp was observed comparing serous borderline tumors to noninvasive and invasive micropapillary serous carcinomas. In contrast, high-grade (conventional serous carcinoma) tumors contained wild-type K-ras in all 23 cases studied and a high frequency of allelic imbalance even in small (early) primary tumors similar to that found in advanced stage tumors. Based on these findings, we propose a dualistic model for ovarian serous carcinogenesis. One pathway involves a stepwise progression from SBT to noninvasive and then invasive MPSC. The other pathway is characterized by rapid progression from the ovarian surface epithelium or inclusion cysts to a conventional (high-grade) serous carcinoma.

Mutational analysis of K-ras segregates ovarian serous carcinomas into two types: Invasive MPSC (low-grade tumor) and conventional serous carcinoma (high-grade tumor)

We previously proposed a dualistic model for ovarian serous carcinogenesis. One pathway involves the stepwise development of invasive micropapillary serous carcinoma (MPSC) from serous borderline tumor (atypical proliferative serous tumor) to noninvasive and then invasive MPSC. The carcinomas that develop in this fashion are characterized by low-grade nuclei and frequent K-ras mutations. They generally pursue an indolent course. In the other pathway conventional serous carcinoma (CSC) develops de novo from the ovarian surface epithelium without what appears to be intermediate stages. These tumors display high-grade nuclei, wild-type K-ras, and are very aggressive. Some of these CSCs display micropapillary architecture and simulate invasive MPSCs. This raises the possibility that these CSCs develop from an invasive MPSC. To address this question we reviewed 31 moderately and poorly differentiated CSCs and identified 7 with morphological features of invasive MPSC. These seven tumors exhibited micropapillary architecture in at least 25% of the tumor but contained high-grade nuclei. The 31 tumors were assessed for K-ras mutations using digital polymerase chain reaction-based analysis. Despite their micropapillary architecture, all 7 CSCs with micropapillary features contained wild-type K-ras as did the other 24 pure CSCs. The results indicate that CSCs with micropapillary features are not derived from invasive MPSCs. The molecular findings also support the view that ovarian serous carcinomas should be graded as low- and high-grade tumors.

HLA-G Immunoreactivity Is Specific for Intermediate Trophoblast in Gestational Trophoblastic Disease and Can Serve as a Useful Marker in Differential Diagnosis

HLA-G is a nonclassical MHC class I antigen that has been shown to be a specific marker for normal intermediate trophoblast (IT). In this study HLA-G immunoreactivity assessed with an HLA-G specific antibody (4H84) was detected in all 14 cases of choriocarcinoma, 14 placental site trophoblastic tumors, 13 epithelioid trophoblastic tumors, 16 placental site nodules, and nine exaggerated placental sites. In contrast, HLA-G immunoreactivity was not detected in 34 nontrophoblastic uterine neoplasms. HLA-G immunoreactivity was present in all the IT cells of exaggerated placental sites and placental site trophoblastic tumors and in 70–100% of IT cells in placental site nodules and epithelioid trophoblastic tumors. The pattern of distribution of HLA-G in different subpopulations of IT confirms the relationship of various trophoblastic lesions to different types of IT (exaggerated placental site and placental site trophoblastic tumor to implantation site IT and placental site nodule and epithelioid trophoblastic tumor to chorionic-type IT) and suggests that choriocarcinoma is related to villous-type IT because the majority of mononucleate cells in this neoplasm were HLA-G immunoreactive. In conclusion, HLA-G immunoreactivity appears to be specific for IT in gestational trophoblastic disease and can serve as a useful marker in the differential diagnosis of these lesions.

Glypican-3 expression in primary and recurrent ovarian carcinomas.

Summary: The identification of glypican-3 (GPC3) expression in malignant neoplasms is potentially of interest because GPC3 might represent a therapeutic target. Tissue microarrays containing tissue cylinders from 308 patients with ovarian carcinomas were used for an immunohistochemical study. There were 255 serous, 38 endometrioid, and 15 clear-cell carcinomas included. From 76 patients, paired tissue samples of primary serous ovarian carcinomas and their corresponding recurrences after platinum-based chemotherapy were available. Glypican-3 was expressed in a total of 17.9% of ovarian carcinomas and was strongly associated with the clear-cell histotype (P = 0.0001). Glypican-3 expression was not associated with tumor stage. Positive staining for GPC3 was also observed in a significant fraction of recurrent carcinomas but was not particularly associated with chemoresponse. In conclusion, our data show that GPC3 is observed in a significant fraction of primary and corresponding recurrent ovarian carcinomas. Glypican-3 may therefore represent a potential target for (second-line) therapy in ovarian cancer.

A Study on Mastectomy Samples to Evaluate Breast Imaging Quality and Potential Clinical Relevance of Differential Phase Contrast Mammography

ObjectivesDifferential phase contrast and scattering-based x-ray mammography has the potential to provide additional and complementary clinically relevant information compared with absorption-based mammography. The purpose of our study was to provide a first statistical evaluation of the imaging capabilities of the new technique compared with digital absorption mammography. Materials and MethodsWe investigated non-fixed mastectomy samples of 33 patients with invasive breast cancer, using grating-based differential phase contrast mammography (mammoDPC) with a conventional, low-brilliance x-ray tube. We simultaneously recorded absorption, differential phase contrast, and small-angle scattering signals that were combined into novel high-frequency-enhanced images with a dedicated image fusion algorithm. Six international, expert breast radiologists evaluated clinical digital and experimental mammograms in a 2-part blinded, prospective independent reader study. The results were statistically analyzed in terms of image quality and clinical relevance. ResultsThe results of the comparison of mammoDPC with clinical digital mammography revealed the general quality of the images to be significantly superior (P < 0.001); sharpness, lesion delineation, as well as the general visibility of calcifications to be significantly more assessable (P < 0.001); and delineation of anatomic components of the specimens (surface structures) to be significantly sharper (P < 0.001). Spiculations were significantly better identified, and the overall clinically relevant information provided by mammoDPC was judged to be superior (P < 0.001). ConclusionsOur results demonstrate that complementary information provided by phase and scattering enhanced mammograms obtained with the mammoDPC approach deliver images of generally superior quality. This technique has the potential to improve radiological breast diagnostics.

Expression of peroxisome proliferator activated receptor γ and cyclo-oxygenase 2 in primary and recurrent ovarian carcinoma

Aim: Peroxisome proliferator-activated receptor γ (PPARγ) has emerged as a potential therapeutic target in several types of cancer. In ovarian carcinomas, limited and conflicting data on PPARγ protein expression have been reported. Methods: The immunoexpression of PPARγ and its putative target cyclo-oxygenase 2 (COX2) was investigated in tumour tissues from 80 patients with primary and corresponding recurrent ovarian serous carcinomas after conventional platinum-based chemotherapy. Results: PPARγ expression was observed in 29% of primary and recurrent carcinomas. In the recurrent tumours, PPARγ expression inversely correlated with COX2 overexpression in both chemosensitive (p = 0.02) and chemoresistant (p = 0.04) carcinomas. Conclusions: The data indicate that PPARγ may represent a potential target for second-line treatment in ovarian cancers.

Comparison of gene expression profiles in core biopsies and corresponding surgical breast cancer samples

IntroductionGene expression profiling has been successfully used to classify breast cancer into clinically distinct subtypes, and to predict the risk of recurrence and treatment response. The aim of this study was to investigate whether the gene expression profile (GEP) detected in a core biopsy (CB) is representative for the entire tumor, since CB is an important tool in breast cancer diagnosis. Moreover, we investigated whether performing CBs prior to the surgical excision could influence the GEP of the respective tumor.MethodsWe quantified the RNA expression of 60 relevant genes by quantitative real-time PCR in paired CBs and surgical specimens from 22 untreated primary breast cancer patients. Subsequently, expression data were compared with independent GEPs obtained from tumors of 317 patients without preceding CB.ResultsIn 82% of the cases the GEP detected in the CB correlated very well with the corresponding profile in the surgical sample (rs ≥ 0.95, p < 0.001). Gene-by-gene analysis revealed four genes significantly elevated in the surgical sample compared to the CB; these comprised genes mainly involved in inflammation and the wound repair process as well as in tumor invasion and metastasis.ConclusionA GEP detected in a CB are representative for the entire tumor and is, therefore, of clinical relevance. The observed alterations of individual genes after performance of CB deserve attention since they might impact the clinical interpretation with respect to prognosis and therapy prediction of the GEP as detected in the surgical specimen following CB performance.

Breast cancer with non-inflammatory skin involvement : current data on an underreported entity and its problematic classification

We evaluated 166 breast cancer cases with non-inflammatory skin involvement (NISI), which were classified in the TNM classification as T4b. The distribution of tumour sizes and stages was: < or =3 cm:24.1%, 3.1-5 cm:21.7%, 5.1-10 cm:33.1%, >10 cm:21.1%; stages:I/II:21.0%, III:43.4%, IV:35.6%. To assess the impact of NISI on axillary lymph node involvement (ALNI), we analyzed a sub-group of 50 patients with tumours < or =5 cm and compared them with a matched control group. NISI was found to be associated with increased ALNI (HR, 2.66; 95%CI, 1.59-4.63; p<0.0001). According to the inherent rules of tumour classification, only tumours with similar morphologic extent and prognostic significance should be combined. Since there is a high grade of heterogeneity, this basic tenet is clearly violated regarding breast cancer with NISI. Our proposal is to eliminate these tumours from the T4 category and to classify them simply by size (T1-3). Due to its prognostic significance, NISI should be indicated by an optional descriptor (e.g. S1).

Toward clinical differential phase contrast mammography: preliminary evaluations and image processing schemes

Phase contrast and scattering-based X-ray imaging are very promising tools for medical diagnostics because they are able to provide additional and complementary information to traditional absorption-based methods. In this work, we discuss the investigation of three native breast samples with a grating interferometer equipped with a conventional X-ray tube, the full study being published in ref. [1]. We briefly introduce a method to fuse absorption, differential phase and scattering signals into a unique image with improved diagnostic contents. Our approach yields complementary and inaccessible information on the electron density distribution and the small-angle scattering power of the sample which could potentially answer clinically relevant, yet unresolved questions such as the capability to unequivocally discern between (pre-) malignant changes and post-operative scars or to distinguish cancer-invaded regions within healthy tissue.