Takaaki Hanyu

Actionable gene-based classification toward precision medicine in gastric cancer

BackgroundIntertumoral heterogeneity represents a significant hurdle to identifying optimized targeted therapies in gastric cancer (GC). To realize precision medicine for GC patients, an actionable gene alteration-based molecular classification that directly associates GCs with targeted therapies is needed.MethodsA total of 207 Japanese patients with GC were included in this study. Formalin-fixed, paraffin-embedded (FFPE) tumor tissues were obtained from surgical or biopsy specimens and were subjected to DNA extraction. We generated comprehensive genomic profiling data using a 435-gene panel including 69 actionable genes paired with US Food and Drug Administration-approved targeted therapies, and the evaluation of Epstein-Barr virus (EBV) infection and microsatellite instability (MSI) status.ResultsComprehensive genomic sequencing detected at least one alteration of 435 cancer-related genes in 194 GCs (93.7%) and of 69 actionable genes in 141 GCs (68.1%). We classified the 207 GCs into four The Cancer Genome Atlas (TCGA) subtypes using the genomic profiling data; EBV (N = 9), MSI (N = 17), chromosomal instability (N = 119), and genomically stable subtype (N = 62). Actionable gene alterations were not specific and were widely observed throughout all TCGA subtypes. To discover a novel classification which more precisely selects candidates for targeted therapies, 207 GCs were classified using hypermutated phenotype and the mutation profile of 69 actionable genes. We identified a hypermutated group (N = 32), while the others (N = 175) were sub-divided into six clusters including five with actionable gene alterations: ERBB2 (N = 25), CDKN2A, and CDKN2B (N = 10), KRAS (N = 10), BRCA2 (N = 9), and ATM cluster (N = 12). The clinical utility of this classification was demonstrated by a case of unresectable GC with a remarkable response to anti-HER2 therapy in the ERBB2 cluster.ConclusionsThis actionable gene-based classification creates a framework for further studies for realizing precision medicine in GC.

Prognostic significance of promyelocytic leukemia expression in gastrointestinal stromal tumor; integrated proteomic and transcriptomic analysis

Prognostic markers are urgently needed to optimize the postoperative treatment strategies for gastrointestinal stromal tumors (GIST). GIST of the small intestine (I‐GIST) show more aggressive behavior than those of the stomach (S‐GIST), and the molecular background of the malignancy in I‐GIST may include potential prognostic biomarkers. We conducted integrated proteomic and transcriptomic analysis to identify genes showing differential expressions according to the tumor site. We generated protein expression profiles for four cases each of surgically resected I‐GIST and S‐GIST using label‐free proteomic analysis. For proteins showing differential expressions, global mRNA expression was compared between 9 I‐GIST and 23 S‐GIST. Among the 2555 genes analyzed, we found that promyelocytic leukemia (PML), a tumor suppressor gene, was significantly downregulated in I‐GIST at both the protein and mRNA levels (P < 0.01; fold difference ≥2.0). Immunohistochemistry of 254 additional cases from multiple clinical facilities showed that PML‐negative cases were significantly frequent in the I‐GIST group (P < 0.001). The 5‐year recurrence‐free survival rate was significantly lower in the PML‐negative than in the PML‐positive cases (60.1% vs 91.7%; P < 0.001). Multivariate analysis revealed that downregulation of PML was an independent unfavorable prognostic factor (hazard ratio = 2.739; P = 0.001). Our study indicated that prognostication based on PML expression may have potential for optimizing the treatment strategy for GIST patients. Further validation studies of PML for clinical application, and investigation for the mechanistic significance of PML to clarify the molecular backgrounds of malignancy in GIST are warranted.

Endobronchial metastasis from adenocarcinoma of gastric cardia 7 years after potentially curable resection

Endobronchial metastasis (EBM) is a rare form of metastasis from extrapulmonary malignant tumors, although there are few reports of EBM from gastric cancer specifically. We report the case of a 51-year-old woman who had undergone gastrectomy for advanced gastric cancer seven years previously but was diagnosed with a solitary lung tumor by follow-up computed tomography. On diagnosis of primary lung cancer, she underwent pulmonary lobectomy, but immunohistochemical examination confirmed the resected tumor to be an EBM from the gastric cancer. Six months later, she was diagnosed with peritoneal metastases and underwent chemotherapy with gastric cancer regimen. She is still alive at 33 mo after the lobectomy. Generally, the prognosis for EBM is poor although multidisciplinary treatment can lead to long-term survival. Precise diagnosis on the basis of detailed pathological and immunohistochemical evaluation can contribute to deciding the most effective treatment and improving prognosis.

Expression of phosphorylated sphingosine kinase 1 is associated with diffuse type and lymphatic invasion in human gastric cancer

Background: Sphingosine‐1‐phosphate, a pleiotropic bioactive lipid mediator, is an important player in cancer progression. Previous studies suggested that sphingosine‐1‐phosphate produced by sphingosine kinase 1, which is activated by phosphorylation, plays important roles in the progression of disease and metastasis. The association between phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase 1 and clinical parameters in human gastric cancer have not been fully investigated to date. Methods: We created phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase expression profiles by immunohistochemistry for 136 patients who underwent operative intervention for gastric cancer in 2007–2009. Phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase expression and compared clinicopathologic factors by univariate and multivariate analyses. Results: The univariate analysis revealed that phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase expression was correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, histologic type, and lymphatic invasion. The multivariate analysis revealed that the diffuse type (odds ratio 2.210; 95% confidence interval, 1.045–4.671, P = .038) and the presence of lymphatic invasion (odds ratio 3.697; 95% confidence interval, 1.161–8.483, P = .002) were associated independently with phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase expression in patients with gastric cancer. The 5‐year rate of disease‐specific survival was 79.3% in patients with phospho‐sphingosine‐1‐phosphate produced by sphingosine kinasephospho‐sphingosine‐1‐phosphate produced by sphingosine kinase‐positive expression and 98.3% in those with phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase‐negative expression (P = .002). In multivariate analysis, however, high phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase expression was not an independent prognostic factor for disease‐specific survival (hazard ratio 5.540; 95% confidence interval, 0.717–42.81, P = .100). Conclusion: We provide the first evidence that diffuse histologic type and lymphatic invasion were independently associated with high phospho‐sphingosine‐1‐phosphate produced by sphingosine kinase expression in gastric cancer patients, indicating a role of sphingosine‐1‐phosphate in disease progression among patients with gastric cancer. (Surgery 2017;160:XXX‐XXX.)

Prognostic analysis of submucosa-invasive gastric cancer with lymph node metastasis

BACKGROUND The aims of this study were to identify prognostic factors of patients with submucosa-invasive (T1b) gastric cancer and to verify the validity of adjuvant chemotherapy for this disease. METHODS We retrospectively examined the cases of 1,236 consecutive patients in our prospectively maintained database with T1b gastric cancer who underwent gastrectomy in 1995-2012. We used 11 clinicopathologic characteristics to identify prognostic factors by univariate and multivariate analyses. We compared the survival of the 160 node-positive T1b gastric cancer patients with that of 133 patients in the same database who had node-positive muscularis propria-invasive (T2) gastric cancer and had undergone gastrectomy without adjuvant chemotherapy during the same period, as a reference cohort. RESULTS The 5-year overall survival rate was 91.4% for all 1,236 patients. Advanced age (hazard ratio [HR] 4.51; 95% confidence interval [CI] 3.26-6.24; P < .01), male sex (HR 2.26; 95% CI 1.56-3.26; P < .01), and the presence of lymph node metastasis (HR 1.89; 95% CI 1.33-2.70; P < .01) were independent prognostic factors. The 5-year overall survival rates were 92.5% in node-negative patients, 84.5% in patients with 1 or 2 metastatic nodes, and 80.1% in patients with 3 or more metastatic nodes (P < .01). The 5-year overall survival rates of the node-positive T1b and T2 gastric cancer patients were 83.6% and 81.2%, respectively (P = .73). CONCLUSION The prognosis of node-positive T1b gastric cancer patients after curative gastrectomy was unsatisfactory. Adjuvant chemotherapy should be considered for these patients, especially those with 3 or more metastatic nodes.

Conservative treatment of esophageal perforation related to a peptic ulcer with pyloric stenosis

We report a case of esophageal perforation (Boerhaave syndrome) caused by vomiting related to a duodenal ulcer with pyloric stenosis. A 45-year-old male presented with left chest pain and dyspnea after forceful vomiting. Chest radiography and computed tomography (CT) revealed a massive left pleural effusion and left tension pneumothorax. Abdominal CT revealed pyloric stenosis with a remarkably dilated stomach. Tube thoracostomy and nasogastric suction were immediately performed and we selected conservative treatment based on the following factors—a stable general condition without sepsis, early diagnosis, and good drainage. Esophagogastroduodenoscopy on hospital day 9 demonstrated a healing ulcer in the lower esophagus and pyloric stenosis. We performed distal gastrectomy as elective surgery for pyloric stenosis due to a duodenal ulcer on hospital day 30. In summary, an esophageal perforation with contamination spreading to the thoracic cavity was successfully treated with conservative treatment.

Internal hernia after laparoscopic-assisted proximal gastrectomy with jejunal interposition for gastric cancer: a case report

Internal hernia after gastrectomy is a rare complication. It can progress rapidly to vascular disturbance, necrosis, and perforation, therefore early diagnosis and surgical treatment is essential. We present a case of internal hernia following laparoscopic-assisted proximal gastrectomy with jejunal interposition reconstruction in a 68-year-old man, who presented with acute abdominal pain and vomiting. Computed tomography showed a whirl sign, ascites, and a closed-loop formation of the small intestine. We diagnosed an internal hernia and performed emergency surgery. Laparotomy revealed chyle-like ascites and extensive small intestine with poor color. We recognized that about 20 cm of jejunum from the ligament of Treitz was strangulated behind the pedicle of the jejunum lifted during laparoscopic-assisted proximal gastrectomy. We relieved the strangulation, whereupon the color of the strangulated intestine was restored. Therefore, we did not perform intestinal resection and reconstruction. Finally, we fixed the jejunal pedicle and mesentery of the transverse colon. We report this case as there are few reported cases of internal hernia after laparoscopic-assisted proximal gastrectomy.

Management of rectal gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. However, rectal GIST is rare, the incident rate of it is approximately 5% of all GISTs. Rectal GIST symptoms generally include bleeding and/or pain and occasionally, urinary symptoms. Immunohistochemical evaluation finds that most rectal GIST tumors are CD117 (KIT) positive, and are sometimes CD34, platelet-derived growth factor receptor alpha (PDGFRA), smooth muscle actin, S-100, or vimentin positive. The National Institutes of Health (NIH) classifies rectal GIST as very-low risk, low risk, intermediate risk, or high risk, and the frequencies have been estimated as 0-23.8% for very-low risk, 0-45% for low risk, 0-34% for intermediate risk, and 21-100% for high risk tumors. The first-line treatment for localized GIST is curative resection, but is difficult in rectal GIST because of anatomical characteristics such as the deep, narrow pelvis and proximity to the sphincter muscle or other organs. Several studies noted the efficacy of the minimally invasive surgery, such as trans-anal, trans-sacral, trans-vaginal resection, or laparoscopic resection. The appropriate surgical procedure should be selected depending on the case. Imatinib mesylate (IM) is indicated as first-line treatment of metastatic or unresectable GIST, and clinical outcomes are correlated with KIT mutation genotype. However, the KIT mutation genotypes in rectal GIST are not well known. In this review, as in other GISTs, a large proportion (59-100%) of rectal GISTs carry exon 11 mutations. Although curative resection is indicated for localized rectal GIST, a high rate of local recurrence is a problem. Multimodal therapy including perioperative IM may improve postoperative outcomes, contributing to anus-preserving surgery. Moreover, KIT mutation analysis before IM treatment is important. This review summarizes current treatment strategies for rectal GIST.

Pathogenic Germline BRCA1/2 Mutations and Familial Predisposition to Gastric Cancer

Most gastric cancers (GCs) are considered sporadic, however familial aggregation occurs in 10% of cases1, 2. Approximately 5% of GCs are caused by an autosomal dominant inherited trait, with carriers having a strongly increased risk of GC and other cancers3. Clinical criteria for this entity were defined by the International Gastric Cancer Linkage Consortium (IGCLC)4. Among these, hereditary diffuse gastric cancer (HDGC) is a well-known type of familial GC (FGC). About 40% of families fulfilling the clinical criteria for HDGC have germline CDH1 mutations5. A subset of the remaining families of HDGC, and ones fulfilling the criteria of other familial GC, harbor pathogenic germline mutation in other genes which associated with hereditary cancer predisposition syndromes4. Hereditary breast and ovarian cancer (HBOC) is one of the best-described inherited cancer predisposition syndromes, caused by pathogenic germline BRCA1 or BRCA2 (BRCA1/2) mutations6–9. The increased risks of cancers other than breast and ovarian cancers were observed in the carriers10. The association between germline BRCA1/2 mutation and increased risk of GC were demonstrated in previous studies for HBOC families11–14. Regarding FGC, a recent large-scale study demonstrated that germline BRCA2 mutations were identified in patients who had a family history which fulfilled the criteria of HDGC, but lacking CDH1 mutations15. Therefore, it is possible that germline BRCA1/2 mutations may cause familial predisposition to GC. Recent advances of comprehensive genomic analysis enable us to identify the genomic alterations in GC16. BRCA1/2 mutations were shown in the subset of GC tumor tissues, however the association between germline BRCA1/2 mutations and familial predisposition to GC were not fully understood. Previously we performed genomic sequencing of 207 Japanese GCs using 435-gene panel, and identified BRCA1/2 mutations in tumor17. In this study, we conducted BRCA1/2 genetic testing in seven Japanese GC patients whose tumor had BRCA1/2 mutations. We identified pathogenic germline BRCA1/2 mutations in three patients, who have a familial component of GC.

Conservative treatment of idiopathic spontaneous pneumoperitoneum in a bedridden patient: a case report

Idiopathic spontaneous pneumoperitoneum is a rare condition that is characterized by intraperitoneal gas for which no clear etiology has been identified. We report here a case of idiopathic spontaneous pneumoperitoneum, which was successfully managed by conservative treatment. A 77-year-old woman who was bedridden with speech disability as a sequela of brain hemorrhage presented at our hospital with a 1-day history of abdominal distention. On physical examination, she had stable vital signs and slight epigastric tenderness on deep palpation without any other signs of peritonitis. A chest radiograph and computed tomography showed that a large amount of free gas extended into the upper abdominal cavity. Esophagogastroduodenoscopy revealed no perforation of the upper gastrointestinal tract. The patient was diagnosed with idiopathic spontaneous pneumoperitoneum, and conservative treatment was selected. The abdominal distension rapidly disappeared, and the patient resumed oral intake on the 5th hospital day without deterioration of symptoms. Knowledge of this rare disease and accurate diagnosis with findings of clinical imaging might contribute towards refraining from unnecessary laparotomy.