Responsabile: Dott. L. Saragoni
Early Gastric Cancer: identification of molecular markers able to distinguish the different lesions with different prognosis (PEN A and PEN B)
Dr. Luca Saragoni (firstname.lastname@example.org)
Dr.ssa Chiara Molinari (email@example.com)
Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy.
Pathology Unit, Morgagni-Pierantoni Hospital, Forlì, Italy.
Department of General Surgery, Morgagni-Pierantoni Hospital, Forlì, Italy.
Principal Investigators: Paola Ulivi, Chiara Molinari, Luca Saragoni, Paolo Morgagni
BACKGROUND AND RATIONALE
An ‘‘early gastric cancer’’ (EGC) is defined as carcinoma limited to gastric mucosa and or submucosa regardless of lymph node status, even if some disputes are present. Numerous studies have focused on key parameters that could be associated with the risk of lymph node metastases or treatment failure in EGC (Murakami T, 1971; Japanese Research Society, 1981; Abe S et al., 1995; Sano T et al., 1992). In our area, which has a high incidence of gastric cancer, EGC represents about 25 % of all gastric cancers treated surgically (Sano T et al., 1993). They are divided into superficial and penetrating tumors (PEN A e PEN B). According to Kodama’s classification, PEN are lesions with a diameter of less than 4 cm that invades the submucosa in a widely penetrating fashion. In particular, PEN B are penetrating “saw teeth” with a better prognosis similar to superficial tumors. On the other hand, PEN A type EGC represents a subgroup of tumors that invades the submucosa extensively, with nodular masses and frequent lymph nodes involvement. A previous experience on 530 patients affected by EGC has demonstrated that there is a significant worse survival probability in node-positive and PEN A patients (Folli S et al., 1995; Saragoni L et al., 1998; Saragoni L et al., 2000). According to these results, subgroups of patients with different prognosis have been identified. The molecular characteristics of the different EGC subgroups are not yet known. A different sialyl Lewisx antigen expression, involved in tumor metastasis and regulated by fucosyltransferases genes, has been shown to be present in PEN A and PEN B tumors (Nakagoe T et al., 2002). Moreover, a recent paper has showed that EGFR overexpression, together with female gender, tumor size and lymphovascular invasion, were predictive risk factor for lymph node metastasis in EGC (Jin EH et al., 2015). Other parameters could be implicated in the different prognosis of the different EGC subtypes. It has been shown that gastric immunophenotype of epithelial dysplasia is associated with a more biological aggressiveness (Valente P et al., 2015). This parameter has never been tested in EGC, according to the different Kodama’s subtypes. Finally, even if a TCGA study gave a complete characterization of gastric tumors, no studies are present in the literature regarding EGC (Cancer Genome Atlas network, 2014; Cui J et al., 2015).
Primary aim: to perform an immunohistochemical and molecular characterization of a case series of PEN A with respect to PEN B tumors
Secondary aim: to perform an immunohistochemical and molecular characterization of a case series of PEN A tumors with respect to a series of T3N0 gastric cancer.
STUDY DESIGN AND METHODS
A retrospective case series of patients with EGC PEN A (n=50), PEN B (n=50) and T3N0 gastric cancer (n=50) will be considered for this study. For each patient a follow up of at least 5-years will be available.
The following determinations will be performed for each case:
In situ determinations: the expression of CD10, MUC-2, CDX2, MUC-6, MUC-5AC, MLH1, E-cadherin, p53, EGFR and Epstein-Barr virus will be analysed by IHC and ISH for phenotypical and molecular subtypes characterization,.
Molecular determinations: Copy number alterations analysis of genes suggested to be of diagnostic and/or clinical relevance in gastric cancer (PIK3CA, EGFR, CDK6, MET, GATA4, FGFR1, MYC, PTP4A3, FGFR2, CCND1, KRAS, KLF5, ERBB2, TOP2A, GATA6 and CCNE1) will be performed by MLPA (P458-B1 probemix kit). P53 gene mutation and MSI will be also analyzed.
The expression of 84 key genes involved in glycosylation will be evaluated by RT2 Profiler PCR Array.
A case series composed of 20 PEN A, 20 PEN B and 20 T3N0 gastric cancer have been previously analyzed in our laboratory. FFPE tissue samples were recovered. CD10, MUC-2, CDX2, MUC-6, MUC-5AC, as well as EGFR and HER2 expression and MSI analysis were performed and data evaluations are ongoing. KRAS , NRAS, BRAF, PIK3CA gene mutations were also performed, and no mutations were found in any EGC.
We expect to found molecular and immunohistechemical features able to distinguish PEN A respect to PEN B tumors, that could explain the different prognostic behavior of the two type of lesions. We also expect to find molecular and immunohistochemical similarities between PEN A tumors and invasive gastric cancer