Jimmy So

Intrinsic Subtypes of Gastric Cancer, Based on Gene Expression Pattern, Predict Survival and Respond Differently to Chemotherapy

BACKGROUND & AIMS Gastric cancer (GC) is a heterogeneous disease comprising multiple subtypes that have distinct biological properties and effects in patients. We sought to identify new, intrinsic subtypes of GC by gene expression analysis of a large panel of GC cell lines. We tested if these subtypes might be associated with differences in patient survival times and responses to various standard-of-care cytotoxic drugs. METHODS We analyzed gene expression profiles for 37 GC cell lines to identify intrinsic GC subtypes. These subtypes were validated in primary tumors from 521 patients in 4 independent cohorts, where the subtypes were determined by either expression profiling or subtype-specific immunohistochemical markers (LGALS4, CDH17). In vitro sensitivity to 3 chemotherapy drugs (5-fluorouracil, cisplatin, oxaliplatin) was also assessed. RESULTS Unsupervised cell line analysis identified 2 major intrinsic genomic subtypes (G-INT and G-DIF) that had distinct patterns of gene expression. The intrinsic subtypes, but not subtypes based on Laurens histopathologic classification, were prognostic of survival, based on univariate and multivariate analysis in multiple patient cohorts. The G-INT cell lines were significantly more sensitive to 5-fluorouracil and oxaliplatin, but more resistant to cisplatin, than the G-DIF cell lines. In patients, intrinsic subtypes were associated with survival time following adjuvant, 5-fluorouracil-based therapy. CONCLUSIONS Intrinsic subtypes of GC, based on distinct patterns of expression, are associated with patient survival and response to chemotherapy. Classification of GC based on intrinsic subtypes might be used to determine prognosis and customize therapy.

Oncogenic pathway combinations predict clinical prognosis in gastric cancer.

Many solid cancers are known to exhibit a high degree of heterogeneity in their deregulation of different oncogenic pathways. We sought to identify major oncogenic pathways in gastric cancer (GC) with significant relationships to patient survival. Using gene expression signatures, we devised an in silico strategy to map patterns of oncogenic pathway activation in 301 primary gastric cancers, the second highest cause of global cancer mortality. We identified three oncogenic pathways (proliferation/stem cell, NF-kappaB, and Wnt/beta-catenin) deregulated in the majority (>70%) of gastric cancers. We functionally validated these pathway predictions in a panel of gastric cancer cell lines. Patient stratification by oncogenic pathway combinations showed reproducible and significant survival differences in multiple cohorts, suggesting that pathway interactions may play an important role in influencing disease behavior. Individual GCs can be successfully taxonomized by oncogenic pathway activity into biologically and clinically relevant subgroups. Predicting pathway activity by expression signatures thus permits the study of multiple cancer-related pathways interacting simultaneously in primary cancers, at a scale not currently achievable by other platforms.

Outcomes of atypical symptoms attributed to gastroesophageal reflux treated by laparoscopic fundoplication

BACKGROUND The introduction of laparoscopic fundoplication (LF) has lowered the threshold for operation in patients with symptoms attributed to gastroesophageal reflux. We sought to determine whether the outcomes in patients referred for atypical symptoms (pulmonary, pharyngolaryngeal, and pain syndromes) were as good as those referred for correction of heartburn and regurgitation (typical symptoms). METHODS Thirty-five of 150 consecutive patients undergoing LF with a minimum of 12 months of follow-up were referred primarily for correction of atypical symptoms. A standard preoperative evaluation included endoscopy, manometry, upper gastrointestinal contrast radiography, and 24-hour pH probe testing (33 of 35 patients with atypical symptoms). Patients completed a symptom questionnaire administered by a study nurse before the operation and 3 and 12 months after the operation. Symptoms were scored from 0 to 10. RESULTS Heartburn was relieved by LF in 93% of patients, whereas only 56% of patients had relief of atypical symptoms. Furthermore, the degree of improvement in typical symptoms was greater than that seen for atypical symptoms as measured by the 0 to 10-symptom rating score (improvement in typical symptoms = 6.2 vs improvement in atypical symptoms = 4.4 [p = 0.01]). The response rate for laryngeal, pulmonary, and epigastric/chest pain symptoms was 78%, 58%, and 48%, respectively. Analysis of factors associated with relief of atypical symptoms revealed that response to a preoperative trial of omeprazole or H2-blockers was significantly associated with successful surgical outcome (p = 0.03). Six of seven patients with laryngeal symptoms who had acid reflux above the cricopharyngeal level shown by dual-probe pH testing had relief of the symptoms after LF. Manometric findings (amplitude of esophageal body contractions, propagation of contractions, and lower esophageal sphincter resting pressure) neither predicted nor correlated with relief of atypical symptoms after the operation. CONCLUSIONS Relief of atypical symptoms attributed to gastroesophageal reflux by LF is less satisfactory and more difficult to predict than relief of heartburn and regurgitation. The only useful preoperative predictors of relief of atypical symptoms in this study were the response to pharmacologic acid suppression and dual-probe pH testing (only in patients with laryngeal symptoms).

Postoperative perineal hernia

PURPOSE: Perineal hernia is an uncommon complication following abdominoperineal resection. The aim of the study was to evaluate the predisposing factors and the optimum method of repair. METHODS: A retrospective review of patients with postoperative perineal hernia at the Massachusetts General Hospital between 1963 and 1995 was performed. RESULTS: Twenty-one patients with perineal hernias were found. The original perineal operations were as follows: abdominoperineal resection in 13 patients, pelvic exenteration in 5 patients, cystourethrectomy in 2 patients, and perineal resection of the rectal stump in 1 patient. The incidence of symptomatic perineal hernia following abdominoperineal resection was estimated to be 0.62 percent. A total of 69 percent of patients had the original perineal wound left partially open, and in 10 percent it was left completely open. The peritoneal defect was not closed in 53 percent of patients, and only 21 percent had closure of the levator defect. Of the 19 patients who had hernia repair, 13 were repaired transperineally and 3 transabdominally and 3 required a combined abdominoperineal approach. The repair methods were as follows: simple closure of the pelvic defect (10 patients), mesh closure (5 patients), gluteus flap (1 patient), and retroflexion of the uterus (2 patients) or bladder (1 patient). Four patients had postoperative complications (mostly wound infections), and the recurrence rate was 16 percent. There was no difference in length of hospitalization among transperineal, transabdominal, and combined approaches. CONCLUSIONS: Primary closure of the perineal wound, with careful avoidance of wound infection is the most important consideration for avoiding a perineal hernia. Repairvia the perineum with simple closure of the defect or a mesh is successful in most cases.

In vivo diagnosis of esophageal cancer using image-guided Raman endoscopy and biomolecular modeling.

The aim of this work was to evaluate the biochemical foundation and clinical merit of multimodal image-guided Raman endoscopy technique for real-time in vivo diagnosis of cancer in the esophagus during clinical endoscopic examinations. A novel fiber-optic Raman endoscopy system was utilized for in vivo esophageal Raman measurements at 785 nm laser excitation within 0.5 second under the multimodal wide-field endoscopic imaging (white light reflectance (WLR) imaging, narrow-band imaging (NBI) and autofluorescence imaging (AFI) guidance. A total of 75 esophageal tissue sites from 27 patients were measured, in which 42 in vivo Raman spectra were from normal tissues and 33 in vivo Raman spectra were from malignant tumors as confirmed by histopathology. The biomolecular modeling (non-negativity-constrained least-squares minimization (NNCLSM) utilizing six basis reference spectra from the representative biochemicals (i.e., actin, collagen, DNA, histones, triolein and glycogen) were employed to estimate the biochemical compositions of esophageal tissue. The resulting diagnostically significant fit coefficients were further utilized through linear discriminant analysis (LDA) and leave-one tissue site-out, cross validation method to develop diagnostic algorithms for esophageal cancer diagnosis. High-quality in vivo Raman spectra in the range of 800–1800 cm−1 can be acquired from normal and cancerous esophageal mucosa in real-time under multimodal endoscopic imaging guidance. Esophageal cancer tissue showed distinct Raman signals mainly associated with cell proliferation, lipid reduction, abnormal nuclear activity and neovasculation. The fit coefficients for actin, DNA, histones, triolein, and glycogen were found to be most significant for construction of the LDA diagnostic model, giving rise to an accuracy of 96.0% (i.e., sensitivity of 97.0% and specificity of 95.2%) for in vivo diagnosis of esophageal cancer. This study demonstrates that multimodal image-guided Raman endoscopy technique in conjunction with biomolecular modeling has promising potential for the real-time, in vivo diagnosis and detection of esophageal cancer during clinical endoscopic examination.

CD44v8-10 is a cancer-specific marker for gastric cancer stem cells

The surface marker CD44 has been identified as one of several markers associated with cancer stem cells (CSC) in solid tumors, but its ubiquitous expression in many cell types, including hematopoietic cells, has hindered its use in targeting CSCs. In this study, 28 paired primary tumor and adjacent nontumor gastric tissue samples were analyzed for cell surface protein expression. Cells that expressed pan-CD44 were found to occur at significantly higher frequency in gastric tumor tissues. We identified CD44v8-10 as the predominant CD44 variant expressed in gastric cancer cells and verified its role as a gastric CSC marker by limiting dilution and serial transplantation assays. Parallel experiments using CD133 failed to enrich for gastric CSCs. Analyses of another 26 primary samples showed significant CD44v8-10 upregulation in gastric tumor sites. Exogenous expression of CD44v8-10 but not CD44 standard (CD44s) increased the frequency of tumor initiation in immunocompromised mice. Reciprocal silencing of total CD44 resulted in reduced tumor-initiating potential of gastric cancer cells that could be rescued by CD44v8-10 but not CD44s expression. Our findings provide important functional evidence that CD44v8-10 marks human gastric CSCs and contributes to tumor initiation, possibly through enhancing oxidative stress defense. In addition, we showed that CD44v8-10 expression is low in normal tissues. Because CD44 also marks CSCs of numerous human cancers, many of which may also overexpress CD44v8-10, CD44v8-10 may provide an avenue to target CSCs in other human cancers.

Characterizing variability in in vivo Raman spectra of different anatomical locations in the upper gastrointestinal tract toward cancer detection

Raman spectroscopy is an optical vibrational technology capable of probing biomolecular changes of tissue associated with cancer transformation. This study aimed to characterize in vivo Raman spectroscopic properties of tissues belonging to different anatomical regions in the upper gastrointestinal (GI) tract and explore the implications for early detection of neoplastic lesions during clinical gastroscopy. A novel fiber-optic Raman endoscopy technique was utilized for real-time in vivo tissue Raman measurements of normal esophageal (distal, middle, and proximal), gastric (antrum, body, and cardia) as well as cancerous esophagous and gastric tissues from 107 patients who underwent endoscopic examinations. The non-negativity-constrained least squares minimization coupled with a reference database of Raman active biochemicals (i.e., actin, histones, collagen, DNA, and triolein) was employed for semiquantitative biomolecular modeling of tissue constituents in the upper GI. A total of 1189 in vivo Raman spectra were acquired from different locations in the upper GI. The Raman spectra among the distal, middle, and proximal sites of the esophagus showed no significant interanatomical variability. The interanatomical variability of Raman spectra among normal gastric tissue (antrum, body, and cardia) was subtle compared to cancerous tissue transformation, whereas biomolecular modeling revealed significant differences between the two organs, particularly in the gastroesophageal junction associated with proteins, DNA, and lipids. Cancerous tissues can be identified across interanatomical regions with accuracies of 89.3% [sensitivity of 92.6% (162∕175); specificity of 88.6% (665∕751)], and of 94.7% [sensitivity of 90.9% (30∕33); specificity of 93.9% (216∕230)] in the gastric and esophagus, respectively, using partial least squares-discriminant analysis together with the leave-one tissue site-out, cross validation. This work demonstrates that Raman endoscopy technique has promising clinical potential for real-time, in vivo diagnosis and detection of malignancies in the upper GI at the molecular level.

Comparison between laparoscopic and conventional omental patch repair for perforated duodenal ulcer

AbstractBackground: The aim of the study is to evaluate the safety and efficacy of laparoscopic omental patch repair. Method: This is a retrospective review of 53 consecutive patients with omental patch repair for perforated duodenal ulcer; 38 underwent conventional open approach and 15 underwent laparoscopic patch repair. The only selection criterion was availability of expertise for laparoscopic repair on the day of admission. By chance, the open group had poorer ASA scores. There were four deaths and five postoperative complications in the open group. Results: Laparoscopic repair was successful in 14 cases with one postoperative complication. Operative time was longer in the laparoscopic group (80 vs 65 min in open group, p= 0.02). Patients required less postoperative analgesics in the laparoscopic group (median amount of pethidine was 75 mg vs 175 mg in the open group, p= 0.03). There was no statistically significant difference in terms of hospital stay and return to normal activities between the two procedures. Follow-up Visick scores were comparable in both groups. Conclusions: Laparoscopic omental patch repair offers a safe alternative to the conventional method and causes less postoperative pain.

Comprehensive long-span paired-end-tag mapping reveals characteristic patterns of structural variations in epithelial cancer genomes

Somatic genome rearrangements are thought to play important roles in cancer development. We optimized a long-span paired-end-tag (PET) sequencing approach using 10-Kb genomic DNA inserts to study human genome structural variations (SVs). The use of a 10-Kb insert size allows the identification of breakpoints within repetitive or homology-containing regions of a few kilobases in size and results in a higher physical coverage compared with small insert libraries with the same sequencing effort. We have applied this approach to comprehensively characterize the SVs of 15 cancer and two noncancer genomes and used a filtering approach to strongly enrich for somatic SVs in the cancer genomes. Our analyses revealed that most inversions, deletions, and insertions are germ-line SVs, whereas tandem duplications, unpaired inversions, interchromosomal translocations, and complex rearrangements are over-represented among somatic rearrangements in cancer genomes. We demonstrate that the quantitative and connective nature of DNA-PET data is precise in delineating the genealogy of complex rearrangement events, we observe signatures that are compatible with breakage-fusion-bridge cycles, and we discover that large duplications are among the initial rearrangements that trigger genome instability for extensive amplification in epithelial cancers.

In vivo diagnosis of gastric cancer using Raman endoscopy and ant colony optimization techniques

This study aims to evaluate the clinical utility of image‐guided Raman endoscopy for in vivo diagnosis of neoplastic lesions in the stomach at gastroscopy. A rapid‐acquisition image‐guided Raman endoscopy system with 785‐nm excitation has been developed to acquire in vivo gastric tissue Raman spectra within 0.5 sec during clinical gastroscopic examinations. A total of 1,063 in vivo Raman spectra were acquired from 238 tissue sites of 67 gastric patients, in which 934 Raman spectra were from normal tissue whereas 129 Raman spectra were from neoplastic gastric tissue. The swarm intelligence‐based algorithm (i.e., ant colony optimization (ACO) integrated with linear discriminant analysis (LDA)) was developed for spectral variables selection to identify the biochemical important Raman bands for differentiation between normal and neoplastic gastric tissue. The ACO‐LDA algorithms together with the leave‐one tissue site‐out, cross validation method identified seven diagnostically important Raman bands in the regions of 850–875, 1,090–1,110, 1,120–1,130, 1,170–1,190, 1,320–1,340, 1,655–1,665 and 1,730–1,745 cm−1 related to proteins, nucleic acids and lipids of tissue and provided a diagnostic sensitivity of 94.6% and specificity of 94.6% for distinction of gastric neoplasia. The predictive sensitivity of 89.3% and specificity of 97.8% were also achieved for an independent test validation dataset (20% of total dataset). This work demonstrates for the first time that the real‐time image‐guided Raman endoscopy associated with ACO‐LDA diagnostic algorithms has potential for the noninvasive, in vivo diagnosis and detection of gastric neoplasia during clinical gastroscopy.