Yohei Miyamae

Significance of epidermal growth factor receptor gene mutations in squamous cell lung carcinoma

Epidermal growth factor receptor (EGFR) gene mutations have been reported to be clinically significant in non-small cell lung cancer (NSCLC). However, because most previous studies focused only on adenocarcinomas, EGFR mutations in other histotypes are poorly investigated. We evaluated the frequency of EGFR gene mutations in squamous cell carcinoma (SCC) and its clinicopathological features. In total, 89 frozen tumor specimens that had been first diagnosed as SCCs, were examined for EGFR mutations in exons 19 and 21 using direct sequencing, PNA-enriched sequencing and SmartAmp2. Additionally, pathological investigation, including immunostaining for p63 and TTF-1, alcian blue staining and EGFR mutation-specific immunohistochemistry in mutation-positive samples was also performed. The frequency of EGFR mutations was 5.6% (5/89); all mutations were deletions in EGFR exon 19. Immunohistological investigation of these samples revealed that two of five were positive for p63 and TTF-1 staining, and showed production of mucin, as evidenced by alcian blue staining. Consequently, three of the samples were considered to be true SCC at final pathological diagnosis, while the remaining two samples were revised to adenosquamous carcinoma and adenocarcinoma. The final frequency of the EGFR mutations in true SCC was 3.4% (3/87). In conclusion, EGFR mutations were found in a small, but significant, number of SCC tumor samples and thus EGFR mutational analysis was useful in the accurate diagnosis of SCC. Our data demonstrate that EGFR mutational analysis should be performed not only in adenocarcinoma, but also in SCC to allow accurate diagnosis and treatment.

Clinicopathological features of lung adenocarcinoma with KRAS mutations.

KRAS and epidermal growth factor receptor (EGFR) mutations are thought to play an important role in the carcinogenesis of lung adenocarcinoma. However, clinicopathological findings of KRAS mutated adenocarcinoma cases have not yet been fully clarified. The authors analyzed the relationship between the KRAS mutation and corresponding clinicopathological findings, focusing on nonmucinous and mucinous bronchioloalveolar elements.

Mutation detection of epidermal growth factor receptor and KRAS genes using the smart amplification process version 2 from formalin-fixed, paraffin-embedded lung cancer tissue.

Recent evidence indicates that the presence of epidermal growth factor receptor (EGFR) or KRAS mutations in non-small cell lung cancer (NSCLC) can predict the response of the tumor to gefinitib. However, it is difficult to detect these mutations using formalin-fixed, paraffin-embedded (FFPE) tissues because the fixation process and aging can damage the DNA. In this study, we describe our work in adapting the Smart Amplification Process version 2 (SmartAmp2) to detect EGFR or KRAS mutations in DNA extracted from FFPE tissues. We were able to detect these mutations in 37 (97%) of 38 FFPE lung cancer tissue samples within 60 minutes with the SmartAmp2 assay and to confirm the correlation between EGFR mutations in FFPE tissues and gefitinib responsiveness. All mutations had previously been confirmed in the 38 samples using DNA extracted from frozen tissues. Electrophoresis results indicated that PCR analysis was not reliable for DNA extracted from FFPE tissue when primers with a long amplicon (>300 bp) were used. This study confirms that the SmartAmp2 assay is suitable for use with DNA extracted from FFPE as well as frozen tissues.

Usefulness of Peptide Nucleic Acid (PNA)-Clamp Smart Amplification Process Version 2 (SmartAmp2) for Clinical Diagnosis of KRAS Codon12 Mutations in Lung Adenocarcinoma Comparison of PNA-Clamp SmartAmp2 and PCR-Related Methods

KRAS is an oncogene that can be activated by mutations. Patients with non-small cell lung cancer who have KRAS mutations do not respond to tyrosine kinase inhibitors; therefore, accurate detection of KRAS mutations is important for deciding therapeutic strategies. Although sequencing-related techniques have been frequently used, they are usually too complex, have low sensitivity, and are time-consuming for routine screening in clinical situations. We evaluated peptide nucleic acid (PNA)-clamp smart amplification process version 2 (SmartAmp2) as a detection method for KRAS codon 12 mutations in patient specimens compared with traditional sequencing and polymerase chain reaction-related methods. Among 172 lung adenocarcinoma samples, direct sequencing, enzyme-enriched sequencing, and PNA-enriched sequencing showed that 16 (9.3%), 26 (15.7%), and 28 (16.3%) tumors, respectively, contained KRAS mutations in codon 12. Using PNA-clamp SmartAmp2, we could identify 31 (18.0%) tumors that had KRAS mutations in codon 12 within 60 minutes, three of which were undetected by polymerase chain reaction-related methods. On the other hand, we examined 30 nonmalignant peripheral lung tissue specimens and found no mutations in any of the samples using PNA-clamp SmartAmp2. In this study, we confirmed that PNA-clamp SmartAmp2 has high sensitivity and accuracy and is suitable for the clinical diagnosis of KRAS codon 12 mutations.

Three-dimensional computed tomography for analyzing the vascular anatomy in laparoscopic surgery for right-sided colon cancer.

Background: The mesenteric vessels have many branching patterns. This study clarified the anatomic relationship between the superior mesenteric vein (SMV), the right colic artery (RCA), and the ileocolic artery (ICA) using 3-dimensional computed tomography (3D-CT). The relationship between the RCA and the right colic vein (RCV) was also examined. Methods: Between April 2006 and July 2011, all patients with colorectal cancer underwent multidetector computed tomography (MDCT) before laparoscopic surgery. The 100 most recent consecutive cases were analyzed. 3D-CT images were made by combining arterial angiography, venous angiography, colonography, tumor, lymph node, and duodenal images. Results: The RCA branched from the SMA in 37 cases (37%); of these, 21 had an ICA that crossed anterior to the SMV and 16 had an ICA that crossed posterior. When the ICA crossed anterior to the SMV, all had an RCA that crossed anterior to the SMV, and no posterior RCA was seen. Furthermore, the RCV joined the SMV in 10 cases (27%) and the gastrocolic trunk in 27 cases (73%). Conclusions: Our study clarified the anatomic variety of the vessels in right-sided colon cancer. Preoperative 3D-CT is useful for understanding the anatomy to ensure a safe, precise operation.

Clinical screening assay for EGFR exon 19 mutations using PNA-clamp smart amplification process version 2 in lung adenocarcinoma.

The presence of EGFR mutations is correlated with a positive therapeutic response to tyrosine kinase inhibitors; therefore, the accurate detection of EGFR mutations is crucial when deciding appropriate therapeutic strategies. Recently, the rapid and sensitive assay smart amplification process version 2 (SmartAmp2) was developed. However, this method can only detect one type of mutation in EGFR exon 19; therefore, we applied the PNA technology to the SmartAmp2 assay to develop PNA-clamp SmartAmp2 for the detection of many types of deletions in EGFR exon 19, in a single reaction. This new assay was evaluated using 172 clinical samples. Thirty-nine (22.7%) samples were found to have deletions by PNA-clamp SmartAmp2; whereas 30 (17.4%) and 38 (22.1%) tumors were found to have deletions by direct sequencing and PNA-enriched sequencing, respectively. Three cases, in which we detected mutations with PNA-clamp SmartAmp2, but not with direct sequencing, were treated with gefitinib, and all cases showed a partial therapeutic response. Using clinical samples, we demonstrated that PNA-clamp SmartAmp2 can detect various types of mutations in EGFR exon 19 in a relatively short time and with high sensitivity. This method detected small amounts of mutant DNA and identified patients for whom clinical information was previously unavailable from other tests. This test may contribute to the administration of efficient therapeutic strategies.

Correlation between computed tomography findings and epidermal growth factor receptor and KRAS gene mutations in patients with pulmonary adenocarcinoma.

We examined the correlation between computed tomography (CT) findings and the incidence of epidermal growth factor receptor (EGFR) and KRAS mutations in lung adenocarcinoma. We analyzed the tumors of 136 patients with surgically resected primary lung adenocarcinoma. CT scans were evaluated for the presence of ground grass opacity (GGO), spiculation and the maximum diameter of the tumor was measured. SMart Amplification Process (ver. 2) was used to detect the presence of EGFR and KRAS mutations. EGFR and KRAS mutations were found in 56 (41.1%) and 25 (18.4%) of the 136 cases, respectively. Although no significant association was found between GGO and EGFR mutations (p=0.07), the EGFR mutation occurred more frequently in male patients with GGO than in those without GGO (p=0.04). The KRAS mutation occurred more frequently in patients whose tumor diameter was ≥ 31 mm than in those whose tumor diameter was <30 mm (p=0.003). Evaluation of CT findings may be helpful for determining the presence of EGFR and KRAS mutations, particularly when it is not possible to obtain a tumor specimen.

Rapid Detection of SNP (c.309T>G) in the MDM2 Gene by the Duplex SmartAmp Method

Background Genetic polymorphisms in the human MDM2 gene are suggested to be a tumor susceptibility marker and a prognostic factor for cancer. It has been reported that a single nucleotide polymorphism (SNP) c.309T>G in the MDM2 gene attenuates the tumor suppressor activity of p53 and accelerates tumor formation in humans. Methodology In this study, to detect the SNP c.309T>G in the MDM2 gene, we have developed a new SNP detection method, named “Duplex SmartAmp,” which enabled us to simultaneously detect both 309T and 309G alleles in one tube. To develop this new method, we introduced new primers i.e., nBP and oBPs, as well as two different fluorescent dyes that separately detect those genetic polymorphisms. Results and Conclusions By the Duplex SmartAmp method, the genetic polymorphisms of the MDM2 gene were detected directly from a small amount of genomic DNA or blood samples. We used 96 genomic DNA and 24 blood samples to validate the Duplex SmartAmp by comparison with results of the conventional PCR-RFLP method; consequently, the Duplex SmartAmp results agreed totally with those of the PCR-RFLP method. Thus, the new SNP detection method is considered useful for detecting the SNP c.309T>G in the MDM2 gene so as to judge cancer susceptibility against some cellular stress in the clinical setting, and also to handle a large number of samples and enable rapid clinical diagnosis.

Laparoscopic resection of a paraganglioma located on the border of the thoracic and abdominal cavities using a transabdominal-transdiaphragmatic approach

We treated a 64‐year‐old woman with high blood pressure. Catecholamine metabolite levels were elevated in the blood and urine. CT revealed a densely stained tumor on the right side of the descending aorta dorsal to the inferior vena cava. PET‐CT revealed abnormal accumulation of 18F‐fluorodeoxyglucose, and 123I‐meta‐iodo‐benzylguanidine uptake was apparent on scintigraphy. The tumor was determined to be a paraganglioma located on the border between the thoracic and abdominal cavities, and laparoscopic tumorectomy was performed. The patient was placed in the left lateral position. The right lobe of the liver was turned over, and we cut the diaphragm to expose the front of the tumor. We resected the straight artery flowing in from the aorta and removed the tumor safely. Herein, we describe the removal of a paravertebral paraganglioma located in the border of the thoracic and abdominal cavities with a laparoscopic transabdominal‐transdiaphragmatic approach.

Securing the surgical field in laparoscopic pancreatectomy using a Penrose drain and Endo Close.

Introduction: We adopted the use of Penrose drains and Endo Close to secure a good surgical field during laparoscopic pancreatectomy. Methods: We used a Penrose drain with threads ligated on both ends to suspend the stomach. We then pulled the threads out of the body from the side of the trocar or from besides the xiphisternum by using Endo Close. In most cases, 2 Penrose drains were used to retract the stomach. When the greater omentum on the left side of the cardia still blocks the surgical field, we sewed the posterior wall of the stomach onto the dome of the diaphragm. Results: The use of 2 Penrose drains and Endo Close were effective to retract the stomach in most cases. However, in 3 cases, we needed to additionally sew the stomach onto the diaphragm to fully open up the field. Conclusion: This is a simple and effective method to ensure a good surgical field.