Reporting Tumor Molecular Heterogeneity in Histopathological Diagnosis

Abstract

BackgroundDetection of molecular tumor heterogeneity has become of paramount importance with the advent of targeted therapies. Analysis for detection should be comprehensive, timely and based on routinely available tumor samples.AimTo evaluate the diagnostic potential of targeted multigene next-generation sequencing (TM-NGS) in characterizing gastrointestinal cancer molecular heterogeneity.Methods35 gastrointestinal tract tumors, five of each intestinal type gastric carcinomas, pancreatic ductal adenocarcinomas, pancreatic intraductal papillary mucinous neoplasms, ampulla of Vater carcinomas, hepatocellular carcinomas, cholangiocarcinomas, pancreatic solid pseudopapillary tumors were assessed for mutations in 46 cancer-associated genes, using Ion Torrent semiconductor-based TM-NGS. One ampulla of Vater carcinoma cell line and one hepatic carcinosarcoma served to assess assay sensitivity. TP53, PIK3CA, KRAS, and BRAF mutations were validated by conventional Sanger sequencing.ResultsTM-NGS yielded overlapping results on matched fresh-frozen and formalin-fixed paraffin-embedded (FFPE) tissues, with a mutation detection limit of 1% for fresh-frozen high molecular weight DNA and 2% for FFPE partially degraded DNA. At least one somatic mutation was observed in all tumors tested; multiple alterations were detected in 20/35 (57%) tumors. Seven cancers displayed significant differences in allelic frequencies for distinct mutations, indicating the presence of intratumor molecular heterogeneity; this was confirmed on selected samples by immunohistochemistry of p53 and Smad4, showing concordance with mutational analysis.ConclusionsTM-NGS is able to detect and quantitate multiple gene alterations from limited amounts of DNA, moving one step closer to a next-generation histopathologic diagnosis that integrates morphologic, immunophenotypic, and multigene mutational analysis on routinely processed tissues, essential for personalized cancer therapy.

An oral cavity squamous cell carcinoma quantitative histomorphometric-based image classifier of nuclear morphology can risk stratify patients for disease-specific survival

“…29–32 It has also been shown that molecular heterogeneity of tumors is reflected in corresponding morphologic heterogeneity on tissue slides. 33–35 The ability to ‘unlock’ subtle, sub-visual attributes of tumors from tissue slides via computerized image analysis offers the opportunity to glean a wealth of information regarding morphologic heterogeneity compared with what may be discerned via traditional visual (or manual) inspection of slides alone.…”

Heterogeneity in Gastric Cancer: From Pure Morphology to Molecular Classifications

“…However, few correlation studies of morphological classification and molecular characteristics have been carried out [77,78] and pathologists should be aware of their pivotal role in this field. In-depth studies combining molecular features with histopathological and IHC profiles may reveal interesting associations and are currently feasible, thanks to new molecular profiling technologies, generating accurate molecular information from formalin-fixed and paraffin-embedded tissues [56,79]. On this note, Setia et al [80] have recently proposed a practical algorithm based on IHC and in situ hybridisation techniques currently available in routine diagnostic practice.…”

Fhit down-regulation is an early event in pancreatic carcinogenesis

“…In this series, FHIT rearrangements observed in PDACs were only in part validated in adjacent PanINs [23]. However, this might be related to molecular heterogeneity observed in PDAC (and therefore in PDAC-associated pre-invasive lesions) [46]. Of note, PanIN lesions are characterized by chromosomal instability [47–50], and therefore the down-regulation of Fhit expression we observed in our series may be associated with FHIT gene loss rather than with epigenetic mechanisms.…”