We report a case of a gastrointestinal stromal tumor(GIST)that originated in the anal canal. A 70's woman with a subcutaneous tumor reaching from the anal canal was referred to our hospital. After a thorough examination, the tumor was resected percutaneously in the jackknife position. Histopathological examination showed proliferation of spindle-shaped tumor cells arranged in irregular bundles. Immunohistochemical staining showed that the tumor was positive for c-kit and CD34, and negative for a-SMA and S-100, so the tumor was diagnosed as GIST. As a-SMA-positive smooth muscle cells were seen around the tumor, we suspected that this tumor originated from the internal sphincter muscle.

A 59-year-old man underwent total gastrectomy(with D2 dissection)and cholecystectomy for gastric cancer and a submucosal tumor of the stomach. The specimen was immunohistochemically positive for c-kit, the Ki-67 label index was 10%, and the mitotic count was 20/HPF. Finally, the patient was diagnosed with high-risk gastrointestinal stromal cancer with normal type gastric cancer. After discharge from hospital, we started administration of TS-1 as adjuvant therapy for the gastric cancer. As multiple recurrences of the GIST in the abdomen developed, the patient underwent 3 radical local resections. Mutational analysis revealed a PDGFRA mutation in exon 18, which causes resistance to both imatinib and sunitinib. As he was refractory to imatinib, the patient received regorafenib. After a while, it caused liver failure, which required 7 rounds of plasmapheresis. The patient died from multiple organ failure resulting from multiple recurrences 4 years after the first surgery.

A 44-year-old man with familial adenomatous polyposis underwent laparoscopic-assistedtotal proctocolectomy with ilealpouch anal anastomosis(IPAA). Computed tomography conducted 21 months after IPAA demonstrated bilateral hydronephrosis andan intra-abdominal mass with a maximal diameter of 22 cm, leading to a diagnosis of stage IV desmoid disease, according to the classification by Church and associates. Six courses of combination chemotherapy with doxorubicin plus dacarbazine were administered. Computed tomography after chemotherapy demonstrated marked shrinkage of the desmoidtumor with intraabdominal air andfluidcollection extending just below the skin of the ileostomy closure site. Stoollike fluidoverflowedspontaneously through the site of the ileostomy closure andthe abscess cavity was successfully drained. The patient was discharged 30 days after the start of drainage. The patient is doing well 10 months after the drainage without regrowth of the desmoid tumor, even though a cavity-like lesion encapsulatedby a thick wall remains.

We report a case of panitumumab-resistant rectal cancer with HER2 gene amplification detected by CancerPlex®. A 51- year-old man was diagnosed with an obstructive rectal cancer having lung and adrenal metastases. He underwent the Hartmann 's operation, and KRAS mutations were not detected. After the surgery, 3 courses of CapeOx plus bevacizumab were administered as first-line chemotherapy; however, the lung and adrenal metastases progressed. Subsequently, 24 courses of IRIS/panitumumab was administered as second-line chemotherapy, and the metastases slowly progressed. Six courses of regorafenib were administered as third-line chemotherapy followed by a course of TAS-102 as fourth-line chemotherapy. Subsequently, a left femoral head metastasis and cerebellar metastases were detected. The patient received best supportive care including palliative femoral head replacement and stereotactic irradiation for the cerebellar metastases, and he died of cancer 3 years 5 months after the primary surgery. The comprehensive genomic analysis focusing on 413 cancer-related genes with CancerPlex®revealed that EGFR, BRAF, KRAS, NRAS, and HRAS had no mutations; however, ERBB2 amplification was detected. Furthermore, immunohistochemical staining revealed overexpression of HER2 protein in both the primary and bone metastatictumor. HER2 and EGFR independently promote the RAS-RAF-MAPK pathway. In the present case, the efficacy of anti-EGFR therapy may be attenuated because of ERBB2 amplification in the metastatic tumor.

A 58-year-old man was admitted with the complaint of bloody stools. Colonoscopy and computed tomography revealed a rectal cancer with a liver metastasis and multiple lung metastases. After administering a regimen comprising 3 courses of XELOX plus bevacizumab chemotherapy, the sizes of the primary and metastatic lesions decreased remarkably. Abdominoperineal resection was performed for local control of the cancer; the specimen from the initial tumor was found to be KRAS wild type. After 14 courses of XELOX chemotherapy, brain metastases were detected. Although 3 courses of IRIS plus panitumumab were administered, the liver, lung, and brain metastases spread rapidly. A comprehensive genomic analysis focused on cancer-related genes with CancerPlex®found a mutation of the BRAF gene(I326V). BRAF is a downstream molecule of KRAS in the RAS-RAF-MAPK pathway. Therefore, this mutation of the BRAF gene has the possibility of causing resistance against panitumumab that was found in this case. Furthermore, we expect that the systematic analysis of oncogene and suppressor oncogenes will enable us to choose the optimal regimen of chemotherapy or molecular targeting therapy for each patient with colorectal cancer.

We report a rare case of male hereditary breast cancer in which a sentinel lymph node biopsy was performed. A 62-yearold man was admitted to our hospital because of a palpable tumor in his right breast. Both his younger sister and daughter had had breast cancer. Genetic testing revealed a morbid mutation in the BRCA2 gene. The tumor was palpated to an elastic hard mass and had a clear border in the right DCE area. We performed a core needle biopsy and diagnosed invasive ductal carcinoma, specifically, cT1cN0cM0, cStage I hereditary breast cancer. The patient underwent mastectomy and a sentinel lymph node biopsy. Nine days later, tamoxifen therapy was initiated. There has been no sign of recurrence during the 9 months after the operation.

A 49-year-old man visited our hospital with a chief complaint of abdominal pain that began 1 day before his visit.An approximately 30 cm tumor that was extensively in contact with the gastric wall in the abdominal cavity was detected on computed tomography(CT).An elevated lesion covered with normal mucosa on the posterior wall of the greater curvature was detected on upper endoscopy.He was diagnosed with a submucosal tumor of the stomach, and he underwent surgery. Surgical findings revealed an elastic soft tumor with a maximal dimension of 38 cm that projected from the posterior wall of the stomach beyond the gastric wall.No invasion and metastasis to other organs were detected.Partial gastrectomy was performed.On histopathological examination, proliferation of atypical round and spindle cells was found, and immunostaining was negative for KIT but positive for CD34.In the gene search, an Asp842Val mutation was detected in exon 18 of the PDGFRA gene.Currently, the patient has survived for 7 months after surgery without recurrence.

A 39-year-old woman underwent right colectomy for type-3 transverse colon cancer, which was histologically identified as well-differentiated stage II A adenocarcinoma with a mucinous component and tumor-infiltrating lymphocytes. The patient was suspected of having Lynch syndrome(LS)since she fulfilled 2 of the revised Bethesda criteria, even though there was no family history of LS. Twelve months after colectomy, abdominal CT revealed thickening of the uterine endometrium. Histopathological examination of biopsy specimens revealed well-differentiated endometrioid carcinoma. Extended hysterectomy with bilateral oophorectomy was performed. Histological examination of the resected specimen revealed well-differentiated endometrioid carcinoma of stage I . Immunohistochemistry analysis of mismatch repair proteins demonstrated loss of MLH1/ PMS2 expression in the colon cancer, but normal expression in the uterine cancer. Genetic testing identified duplication of exons 10-15 of the MLH1 gene, leading to a definitive diagnosis of LS. The patient has not shown any evidence of recurrence or new LS-associated tumors in the 12 years since the last surgery. There is an ongoing debate regarding the pathogenesis of endometrioid cancer, and this case emphasizes the importance of surveillance for gynecological malignancies after colon cancer surgery in female LS patients.

RAS mutation is an established predictive biomarker of resistance to anti-epidermal growth factor receptor(EGFR)therapy in metastatic colorectal cancer. In addition, previous studies identified mutations in ERBB2, FGFR1, PDGFRA, BRAF, MAP2K1, PTEN, and PIK3CA as potential mechanisms of resistance to anti-EGFR therapy. Testing for these mutations might be necessary to determine eligibility for anti-EGFR therapy in patients with metastatic colorectal cancer. CancerPlex®is a nextgeneration sequencer for 413 cancer genes. An analysis panel includes genes that may be associated with resistance to anti- EGFR therapy. A 65-year-old man with unresectable rectal cancer, multiple lung metastases, and a bulky liver metastasis was evaluated for expression of genes associated with resistance to anti-EGFR. The analysis found that all genes indicating resistance were wild-type genes. Cetuximab monotherapy was administered after rectal resection, with dramatic shrinkage of the metastatic tumors. A more accurate selection of patients according to tumor genetic status using CancerPlex®might improve the risk-benefit profile of anti-EGFR therapy.

Mismatch repair(MMR)protein deficiency in colorectal cancer is well correlated with high-level microsatellite instability (MSI-H). There are little data on mismatch repair deficiency(dMMR)colorectal cancers in Japan. In addition, we have no available data on the therapeutic efficacy of oxaliplatin(oxa)-based chemotherapy, one of the standard treatment regimens for metastatic colorectal cancer, for patients with dMMR colorectal cancer. The subjects were 254 patients with Stage IV colorectal cancer whose tumors were immunohistochemically stained for MMR proteins, MLH1, MSH2, MSH6, and PMS2. Patients who underwent R0 resection were excluded. Clinicopathologic factors and the efficacy of oxa-based chemotherapy were compared between patients with dMMR colorectal cancer and those with mismatch repair proficient(pMMR)colorectal cancer. There were 7(2.8%)patients with dMMR. Four patients demonstrated both MLH1 and PMS2 loss, while 3 patients demonstrated both MSH2 and MSH6 loss. Though the dMMR had a higher frequency in female patients(p=0.02) and a lower frequency in those with liver metastasis(p<0.01), the other clinicopathologic factors evaluated did not significantly differ between the dMMR group and the pMMR group. One hundred and fifty patients with unresectable disease or R1/2 resection received first-line oxa-based chemotherapy. The median overall survival was 23.2 months and 16.2 months in patients with dMMR(n=4)and those with pMMR, respectively(n=146)(p=0.33). The frequency of dMMR amongStag e IV colorectal cancers was lower than those(4-11%)reported in Western countries. Therefore, the clinical significance of universal screeningfor dMMR in all colorectal cancer samples may not be valid. Concerningsurvival benefit, oxa-based chemotherapy seems to be an effective alternative in clinical practice for metastatic colorectal cancer patients with dMMR.

BRAF V600E mutation plays an important role in the serrated neoplasia pathway of colorectal tumorigenesis and is a negative predictive factor for chemotherapy response as well as a prognostic factor in patients with colorectal cancer. To evaluate BRAF V600E mutations, a conventional polymerase chain reaction(PCR)is performed but recently immunohistochemistry (IHC)with a BRAF antibody has been used. Although similarities between the PCR and IHC methods have been reported, some investigators have doubts about the usefulness of IHC for BRAF mutation analysis. The subjects were 38 colorectal cancer patients with tumors demonstrating loss of both MLH1 and PMS2, and high-level microsatellite instability. Of the original 39 patients, 1 was excluded due to Lynch syndrome, which was identified using germline mutation testing. The mutation rate of BRAF V600E was 57.9% using both methods, but the concordance rate was 68.4%, with a kappa-value of 0.33. We should consider the usefulness of the IHC method in the evaluation of BRAF mutations in colorectal cancer patients.

Information on the cancer genome has accumulated rapidly, since approximately 2009, with the use of second-generation sequencing technology. Malignant lymphoma is no exception. In mature B-cell lymphomas, which constitute the vast majority of non-Hodgkin lymphomas, frequent mutations are identified in genes involved in signaling pathways, histone-modifying molecules, the DNA damage-response pathway, etc. The signaling pathways in which multiple genes are mutated include immune cell-specific pathways such as the B-cell receptor, the Toll-like receptor, and their downstream NF-κB signaling pathways, as well as the NOTCH signaling pathway. In mature T/NK-cell lymphomas, mutations accumulate in genes involved in the T-cell receptor pathway and its downstream NF-κB signaling pathway, regulators of DNA methylation, the JAK-STAT pathway, etc. Many of these mutations are found in multiple types of lymphomas but the frequencies of each gene mutation differ among diseases, demonstrating characteristic profiles. This cumulative and growing fund of knowledge provides an important basis for the development of new molecular-targeted drugs.

Acute myeloid leukemia (AML) is a heterogeneous disease, the onset of which involves a variety of chromosomal abnormalities and gene mutations. In recent years, the use of next-generation sequencers has facilitated intensive exploration of gene mutations resulting in the discovery of many AML-related gene mutations, and in clarifying the clonal evolution process of relapse. Epigenetic regulatory gene mutations have occurred in pre-leukemic cells with normal differentiation potential, and the acquisition of numerous genetic mutations was found to be strongly associated with AML onset, with further co-mutations contributing to clonal diversity and leading to the generation of treatment-resistant clones. As a result of these fruitful findings, the gene mutations of AML are becoming useful as not only prognostic factors but also the targets of molecular medicines such as FLT3 and IDH inhibitors. Most notably, several guidelines have proposed a prognostic classification that groups FLT3ITD, NPM1 mutation, and CEBPA mutation together under conventional chromosomal aberrations. This review outlines recent findings pertaining to the gene mutations in AML.

This review outlines recent advances in the understanding of gene alterations and the genetic background associated with myeloproliferative neoplasms (MPNs), as well as describing the roles of these genetic factors in the development of MPNs. JAK2, CALR, and MPL mutations that are specifically found in patients with MPNs have been shown to constitutively activate cytokine receptors. Other mutations that are commonly found in hematopoietic malignancies have been demonstrated to synergize with disease-specific mutations and to accelerate the development of MPN, or to define the disease subtype. However, some of these mutations are found in healthy elderly persons, such that the mechanism of MPN development remains elusive. Further analyses including those for genetic factors associated with the occurrence of MPN will lead to a complete understanding of MPN development.

A 67-year-old woman was detected stage III B adenocarcinoma of the left lung, with epidermal growth factor receptor(EGFR) -mutation. Since chest computed tomography showed enlarged lymph nodes in stations 7 and 1R-4R, radiochemotherapy was recommended. However, she declined radiochemotherapy and the chemotherapy after tumor reduction surgery was chosen. She underwent resection of the left lower lobe and lingular segment, and mediastinal lymph node dissection through a posterolateral thoracotomy by extended bronchoplasty(type C) due to the extranodal invasion of lymph nodes to the lingular segmental bronchus. At postoperative day 21, she underwent right superior mediastinal lymph node dissection through a median sternotomy. Postoperatively, she received 6 cycles of chemotherapy with carboplatin plus paclitaxel followed by gefitinib. 1.5 years later, gamma knife surgery was done for multiple cerebral metastases, followed by 4 cycles of chemotherapy with cisplatin plus pemetrexed and then erlotinib. Six years after surgery, she is surviving without any evidence of disease recurrence. Tumor reduction surgery, when followed by chemotherapy, for EGFR-mutant lung adenocarcinoma is likely to lead to long-term survival.

Recently, targeted drugs have been developed for the treatment of colorectal cancer(CRC). Among targets, it is well known that KRAS mutations are associated with resistance to epidermal growth factor receptor(EGFR)monoclonal antibodies. However, response rates using anti-EGFR monotherapy for CRC were less than 20-30% in previous clinical studies. Thus, because the RAS/MAP2K/MAPK and PI3K/AKT pathways are associated with CRC resistance to chemotherapy, we analyzed gene mutations in Stage IV CRC patients using a genomic test(CancerPlex®). Medical records were reviewed for 112 patients who received treatment for CRC between 2007 and 2015 in Niigata University Medical and Dental Hospital or Niigata Cancer Center Hospital. There were 66 male and 46 female patients, and their median age was 62.5(range, 30-86) years. Cluster analyses were performed in 110 non-hypermutated Japanese CRC patients using Euclidean distance and Ward's clustering method, and 6 typical groups were identified. Among these, patients with all wild-type actionable genes benefited from anti-EGFR therapies. The expense of targeted drugs warrants consideration of cost-effectiveness during treatment decision-making for advanced CRC patients. To this end, based on the genetic information on CRC, it is possible to develop precision medicine using CancerPlex®.

Leukemia is derived from hematopoietic stem/progenitor cells that have acquired genetic abnormalities, leading to malignant transformation. The basis of therapyfor leukemia is a combination of anti-cancer drugs based on risk stratification. The overall 5-year survival rate in leukemia patients of all ages is still 40%, although it has improved in pediatric patients. Leuke- mia itself is a heterogeneous disease that includes various entities/subtypes with different pathogenic gene aberrations. Selection of the treatment strategylargelydepends on risk stratification, and this in turn is mainlybased on specific recurrent chromosome aberrations. However, in acute myeloid leukemia(AML), a significant proportion of patients present with a normal karyotype according to conventional cytogenetic analysis and are classified into an intermediate-risk group, which actuallyconsists of various subtypes with different prognoses. In addition, leukemic cells usuallyharbor one or more driver mutations among their various genetic aberrations, and these driver mutations could affect prognosis. The discoveryof additional mutations in genes such as NPM1, CEBPA and FLT3, which are frequent in AML patients with a normal karyotype, have improved the precision of risk stratification in AML. In this regard, array-based gene expression analysis and whole exome/ transcriptome sequencing could be useful tools for identifying the whole spectrum of genetic aberrations, or for compiling a complete list of mutated genes within leukemic cells. Genetic profiling information obtained using these newlydeveloped methods could provide more accurate information for molecular subtyping and risk stratification in leukemia.

Multigene assays that simultaneously measure the expression of various breast cancer genes have been developed to guide the use of adjuvant chemotherapy in early breast cancer. The efficacy of adjuvant therapies depends on the recurrence risk for an individual patient. As a result, accurate prediction of the recurrence risk is vital for precise adjuvant chemotherapy in individual breast cancer patients. The recurrence risk as typically assessed by conventional examination of histological data of immuno-histological biomarkers(ER, PR, HER2, and Ki-67)is not sufficient to select subsets of patients. Therefore, validated gene expression signatures are useful, in addition to well-established clinico-pathological factors. Available gene expression assay systems, such as MammaPrint®, Oncotype DX®, PAM50 ROR, GGI, EndoPredict®(EP), Breast Cancer IndexSM(BCI), and Curebest®95GC Breast, are recommended. While MammaPrint®and Oncotype DX®are the most predictive of the recurrence risk within the first 5 years of diagnosis, BCI and EPclin have demonstrated utility in predicting late recurrence. In addition, PAM50 provides further biological insights by classifying breast cancers into intrinsic molecular subtypes. These gene expression signatures have become important tools in clinical practice for the identification of low-risk endocrine-positive patients in whom chemotherapy could be avoided. However, there is much work left in the development of a molecular classification considering the biology and novel therapeutic targets in high-risk recurrent disease because chemotherapy has only modest benefits in this population. The recognition of genomic mutations and their relationship to a patient's responsiveness to various therapies will provide important breakthroughs toward precision medicine.