BackgroundTo screen tumors with microsatellite instability (MSI) arising due to DNA mismatch repair deficiency (dMMR), a panel of five quasi-monomorphic mononucleotide-repeat markers amplified in a multiplex PCR (Pentaplex) are commonly used. In spite of its several strengths, the pentaplex assay is not robust at detecting the loss of MSH6-deficiency (dMSH6). In order to overcome this challenge, we designed this study to develop and optimize a panel of four quasi-monomorphic mononucleotide-repeat markers (Tetraplex) for identifying solid tumors with dMMR, especially dMSH6.MethodsTo improve the sensitivity for tumors with dMMR, we established a quasi-monomorphic variant range (QMVR) of 3–4 bp for the four Tetraplex markers. Thereafter, to confirm the accuracy of this assay, we examined 317 colorectal cancer (CRC) specimens, comprising of 105 dMMR [45 MutL homolog (MLH)1-deficient, 45 MutS protein homolog (MSH)2-deficient, and 15 MSH6-deficient tumors] and 212 MMR-proficient (pMMR) tumors as a test set. In addition, we analyzed a cohort of 138 endometrial cancers (EC) by immunohistochemistry to determine MMR protein expression and validation of our new MSI assay.ResultsUsing the criteria of ≥ 1 unstable markers as MSI-positive tumor, our assay resulted in a sensitivity of 97.1% [95% confidence interval (CI) = 91.9–99.0%] for dMMR, and a specificity of 95.3% (95% CI = 91.5–97.4%) for pMMR CRC specimens. Among the 138 EC specimens, 41 were dMMR according to immunohistochemistry. Herein, our Tetraplex assay detected dMMR tumors with a sensitivity of 92.7% (95% CI = 80.6–97.5%) and a specificity of 97.9% (95% CI = 92.8–99.4%) for pMMR tumors. With respect to tumors with dMSH6, in the CRC-validation set, Tetraplex detected dMSH6 tumors with a sensitivity of 86.7% (13 of 15 dMSH6 CRCs), which was subsequently validated in the EC test set as well (sensitivity, 75.0%; 6 of 8 dMSH6 ECs).ConclusionsOur newly optimized Tetraplex system will help offer a robust and highly sensitive assay for the identification of dMMR in solid tumors.Electronic supplementary materialThe online version of this article (10.1186/s12967-017-1376-4) contains supplementary material, which is available to authorized users.
Primary hepatic leiomyosarcoma is a particularly rare tumor with a poor prognosis. Curative resection is currently the only effective treatment, and the efficacy of chemotherapy is unclear. This represents the first case report of a patient with primary hepatic leiomyosarcoma co-existing with metastatic liver carcinoma. We present a 59-year-old man who was diagnosed preoperatively with rectal cancer with multiple liver metastases. He underwent a curative hepatectomy after a series of chemotherapy regimens with modified FOLFOX6 consisting of 5-fluorouracil, leucovorin and oxaliplatin plus bevacizumab, FOLFIRI consisting of 5-fluorouracil, leucovorin and irinotecan plus bevacizumab, and irinotecan plus cetuximab. One of the liver tumors showed a different response to chemotherapy and was diagnosed as a leiomyosarcoma following histopathological examination. This case suggests that irinotecan has the potential to inhibit the growth of hepatic leiomyosarcomas. The possibility of comorbid different histological types of tumors should be suspected when considering the treatment of multiple liver tumors.
BackgroundThe gene expressions of netrin-1 dependence receptors, DCC and UNC5C, are frequently downregulated in many cancers. We hypothesized that downregulation of DCC and UNC5C has an important growth regulatory function in gastric tumorigenesis.ResultsIn the present study, a series of genetic and epigenetic analyses for DCC and UNC5C were performed in a Japanese cohort of 98 sporadic gastric cancers and corresponding normal gastric mucosa specimens. Loss of heterozygosity (LOH) analyses and microsatellite instability (MSI) analysis was applied to determine chromosomal instability (CIN) and MSI phenotypes, respectively. More than 5 % methylation in the DCC and UNC5C promoters were found in 45 % (44/98) and 32 % (31/98) gastric cancers, respectively, and in 9 % (9/105) and 5 % (5/105) normal gastric mucosa, respectively. Overall, 70 % (58 of 83 informative cases) and 51 % (40 of 79 informative cases) of gastric cancers harbored either LOH or aberrant methylation in the DCC and UNC5C genes, respectively. In total, 77 % (51 of 66 informative cases) of gastric cancers showed cumulative defects in these two dependence receptors and were significantly associated with chromosomal instability. Both DCC and UNC5C were inactivated in 97 % of CIN-positive gastric cancers and in 55 % of CIN-negative gastric cancers.ConclusionsDefect in netrin receptors is a common feature in gastric cancers. DCC alterations are apparent in the early stages, and UNC5C alterations escalate with the progression of the disease, suggesting that the cumulative alterations of netrin-1 receptors was a late event in gastric cancer progression and emphasizing the importance of this growth regulatory pathway in gastric carcinogenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-015-0096-y) contains supplementary material, which is available to authorized users.
It should be noted that the serum CEA level can become elevated in severe stercoral colitis. Marked elevation of the serum CEA level in stercoral colitis may suggest the necessity of surgery in patients with stercoral colitis.
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