Publications by authors named "Walawee Chaiyapan"

3 Publications

  • Page 1 of 1

Clinical outcomes of gastrointestinal stromal tumor in southern Thailand.

World J Gastrointest Oncol 2012 Nov;4(11):216-22

Kittima Pornsuksiri, Siripong Chewatanakornkul, Walawee Chaiyapan, Surasak Sangkhathat, Department of Surgery and Tumor Biology Research Unit, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand.

Aim: To review a single institutional experience in clinical management of gastrointestinal stromal tumors (GIST) and analyze for factors determining treatment outcome.

Methods: Clinicopathological data of patients with a diagnosis of GIST who were treated at our institute during November 2004 to September 2009 were retrospectively reviewed.

Results: Ninety-nine cases were included in the analysis. Primary tumor sites were at the stomach in and small bowel in 44% and 33%, respectively. Thirty-one cases already had metastasis at presentation and the most common metastatic site was the liver. Sixty-four cases (65%) were in the high-risk category. Surgical treatment was performed in 77 cases (78%), 3 of whom received upfront targeted therapy. Complete resection was achieved in 56 cases (73% of operative cases) and of whom 27 developed local recurrence or distant metastasis at a median duration of 2 years. Imatinib was given as a primary therapy in unresectable cases (25 cases) and as an adjuvant in cases with residual tumor (21 cases). Targeted therapy gave partial response in 7 cases (15%), stable disease in 27 cases (57%) and progressive disease in 13 cases (28%). Four-year overall survival was 74% (95% CI: 61%-83%). Univariate survival analysis found that low-risk tumor, gastric site, complete resection and response to imatinib were associated with better survival.

Conclusion: The overall outcomes of GIST can be predicted by risk-categorization. Surgery alone may not be a curative treatment for GIST. Response to targeted therapy is a crucial survival determinant in these patients.
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November 2012

Peripheral precocious puberty in a male caused by Leydig cell adenoma harboring a somatic mutation of the LHR gene: report of a case.

J Med Assoc Thai 2010 Sep;93(9):1093-7

Tumor Biology Research Group, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand.

While a germline activating mutation of the luteinizing hormone receptor (LHR) gene is known to cause autonomous production of testosterone from testicular Leydig cells in male-limited precocious puberty, only a few studies have addressed the role of somatic LHR mutation in testicular pathology. The authors report a case of a 6-year-old boy who developed secondary sex characteristics including facial acne, enlarging genitalia, and aggressive behavior, for which serial biochemical evaluation confirmed the status of peripheral precocious puberty. Examination revealed asymmetrical testicular volume, following which a left testicular tumor was detected through ultrasonography. A left orchiectomy was performed, and histopathology revealed a well-circumscribed Leydig cell tumor Molecular study of the exon 11 of the LHR gene revealed a missense mutation at the nucleotide position 1,732, leading to a substitution of histidine for aspartic acid at codon 578. Interestingly, the substitution was consistent with all previously reported LHR alteration in pediatric Leydig cell adenoma, but which had never before been reported in male-limited precocious puberty, suggesting that the mutation is a molecular signature of the adenoma.
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September 2010

Immunohistological evidence for Wnt-signaling activation in Peutz-Jeghers polyposis.

Pediatr Surg Int 2010 Feb 18;26(2):173-7. Epub 2009 Dec 18.

Tumor Biology Research Unit, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, 90110, Thailand.

Objective: Molecular pathogenesis of gastrointestinal polyposis in Peutz-Jegher's syndrome (PJS) has been linked to the loss-of-function mutation of LKB1. Recent functional genetic studies have pointed out that LKB1 plays a physiological role in controlling the Wnt-signaling pathway and activation of the pathway as a consequence of LKB1 haploinsufficiency might be responsible for the development of harmatomatous polyps. This study aimed to look for immunohistochemical evidence of Wnt-signaling activation in PJS polyps.

Method: Beta-catenin immunohistochemistry patterns were evaluated in gastrointestinal polyps from five cases of PJS. All patients were also evaluated for germline mutations of LKB1 and somatic mutations of beta-catenin in the polyps.

Results: Four of the five cases had germline mutations of LKB1, including two novel mutations, a one-base insertion at codon 53 and a large deletion encompassing exon 3 (codon 136-155). PJS polyps from all patients showed generalized membrane and cytoplasmic localizations of beta-catenin along the mucosal endothelium. Polyps from two cases with LKB1 mutations revealed moderate-intensity nuclear staining in approximately 20 and 70% of the polyps.

Conclusion: The study offers additional evidence of Wnt-signaling activation in PJS polyp development at the tissue level, although the degree of up-regulation was not as high as has been found in Wnt-associated neoplasms.
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February 2010