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  1. Prasad U, Pua KC
    Med J Malaysia, 2000 Jun;55(2):230-5.
    PMID: 19839151
    One hundred consecutive newly diagnosed patients with nasopharyngeal carcinoma (NPC) since January 1994 were the subjects for studying various factors that contribute to the delay in the confirmation of the diagnosis. Seventy-nine of them were males and the peak age of incidence was the fifth decade. Ninety two percent were Chinese, 7% Malay and 1% Indian. Seventy six percent were agriculture workers or labourers with 66% having either no formal education (16%) or only primary level education (50%). In 50% of patients neck swelling was the first presenting symptom, 26% had nasal symptoms, 12% ear symptoms and 11% has symptoms due to intracranial extension of tumour. As many as 80% were at UICC Stage IV at the time of diagnosis. While the median delay, on the part of patients, in consulting a doctor was 2.5 days, the median delay on the part of the doctors to confirm the diagnosis of NPC was 127 days, the delays was particularly worse when the patients presented with ear symptoms (266 days) followed by those with neck swelling (94 days). For those patients who were required to undergo more than one nasopharyngoscopy and biopsy the median doctor's delay was 144 days. Since 82% of patient's had first consulted general practitioners, it is suggested that their level of awareness with regards to the diagnosis of NPC be significantly raised so that the delay on their part be greatly minimized.
  2. Mawaddah A, See-Sze S, Marina MB, Pua KC, Abdullah-Sani M
    MyJurnal
    Total thyroidectomy or at least hemithyroidectomy is routinely performed alongside total laryngectomy in patients with advanced carcinoma of the larynx. Life-threatening hypocalcaemia and hypothyroidism are common sequelae especially with adjuvant radiation. The study aims to determine the incidence of microscopic thyroid gland invasion and challenge the idea of routine thyroidectomy in advanced carcinoma of the larynx. Materials and Methods:This study was a retrospective observational study. It was done in two tertiary centres in Malaysia between 2003 and 2013 for a total duration of 11 years. A total of 72 patients were included in this study. Data from medical records, operative notes, and histopathological reports were collected and analysed. Results: Three patients (4.2%) had the presence of microscopic thyroid gland invasion. There were no significant associations between microscopic thyroid gland invasion and tumour subsites, histological types of a tumour nor T staging (p>0.05) Conclusion: The incidence of microscopic thyroid gland invasion in advance carcinoma of the larynx is low, disavowing routine thyroidectomy. Limitations: Some factors such as cartilage invasion on CT imaging and central lymph node treatment were not considered due to limitations in case documentation.
  3. Lim AL, Pua KC
    Med J Malaysia, 2012 Jun;67(3):340-1.
    PMID: 23082433 MyJurnal
    Lemierre syndrome is an uncommon disease which commonly arise from acute bacterial oropharyngeal infection. This disease was first described in 1900 by Courmont and Cade Lemierre. It is commonly caused by Fusobacterium necrophorum. Lemierre syndrome has been reported to be serious and potentially fatal in the preantibiotic era. It is characterized by an oropharyngeal infection leading to secondary septic thrombophlebitis of the internal jugular vein with embolization to the lungs and other organs. The incidence has become relatively rare at present and is usually only diagnosed when unsuspected culture results are available. We report a case of Lemierre syndrome which was recently diagnosed in our centre.
  4. Chen I, Jamal S, Pua KC
    Malays Fam Physician, 2015;10(3):32-4.
    PMID: 27570606 MyJurnal
    Primary tuberculosis (TB) of the hard palate is very rare. A 74-year-old man was presented with 6-month history of dysphagia along with an irregular mass in the hard and soft palate. Magnetic resonance imaging (MRI) revealed thickened and increased signal intensity within hard and soft palate. Tissue biopsy showed focal caseating granulomatous-like lesion and the histochemical staining using Ziehl-Neelsen stain for acid-fast bacilli was positive. Positive histochemical studies provided evidences that the hard palate mass was most likely due to TB. Thus, the patient was started on antituberculous therapy.
  5. Lim AL, Zahirrudin Z, Pua KC
    Med J Malaysia, 2012 Aug;67(4):428-9.
    PMID: 23082458 MyJurnal
    Nasopharnygeal carcinoma is known to be the commonest tumour of the nasopharynx. However, the incidence of nasopharngeal carcinosarcoma is extremely rare. Carcinosarcoma has been reported to be aggressive in nature and therefore early diagnosis and prompt treatment is important. We report a young lady who was diagnosed with nasopharyngeal carcinosarcoma in our centre. She presented with only 2 weeks history of nose block and was noted to have a mass occupying the nasopharynx with neck metastasis. She underwent panendoscope and biopsy with radical radiotherapy.
  6. Ng SY, Pua KC, Zahirrudin Z
    Med J Malaysia, 2015 Dec;70(6):367-8.
    PMID: 26988214 MyJurnal
    Temporal bone squamous cell carcinoma (TBSCC) is rare and poses difficulties in diagnosing, staging and management. We describe a case series with six patients who were diagnosed TBSCC, from January 2009 to June 2014, with median age of 62 years old. All patients presented with blood-stain discharge and external auditory canal mass, showing that these findings should highly alert the diagnosis of TBSCC. Three patients staged T3 and another three with T4 disease. High-resolution CT (HRCT) temporal findings were noted to be different from intraoperative findings and therefore we conclude that MRI should be done to look for middle ear involvement or other soft tissue invasion for more accurate staging. Lateral temporal bone resection (LTBR) and parotidectomy was done for four patients with or without neck dissection. Patients with positive margin, perineural invasion or parotid and glenoid involvement carry poorer prognosis and postoperative radiotherapy may improve the survival rate. One patient had successful tumor resection via piecemeal removal approach in contrast with the recommended en bloc resection shows that with negative margin achieved, piecemeal removal approach can be a good option for patients with T2-3 disease. In general, T4 tumor has dismal outcome regardless of surgery or radiotherapy given.
  7. Yeoh XY, Lim PS, Pua KC
    Case Rep Otolaryngol, 2016;2016:7810857.
    PMID: 27668115 DOI: 10.1155/2016/7810857
    Intracranial complications of chronic otitis media have been on the decline with advent of antibiotics. Septic thrombosis of the sigmoid sinus is rarer compared to commoner complications such as otogenic brain abscesses and meningitis. This patient presented with recurrent infection after left mastoidectomy secondary to cholesteatoma and a contralateral internal jugular vein thrombosis with parapharyngeal abscess, which was drained. He recovered well postoperatively with antibiotics.
  8. Pua KC, Khoo AS, Yap YY, Subramaniam SK, Ong CA, Gopala Krishnan G, et al.
    Med J Malaysia, 2008 Sep;63 Suppl C:59-62.
    PMID: 19230249
    Nasopharyngeal carcinoma (NPC) is a cancer which is common in Asia. We report the establishment and early results of a multi-institutional prospective study of nasopharyngeal carcinoma, which seeks to systematically collect data as well as blood and tumour tissue samples from patients diagnosed with nasopharyngeal cancer at six centres in Malaysia. A total of 484 confirmed NPC cases were reported from the six participating centres between 1st July 2007 and 29th February 2008. Of these, 225 were newly diagnosed cases, 53 were recurrent cases and 206 were in remission at the time of reporting. Amongst the newly diagnosed cases, the most common presenting symptom was the presence of neck lumps (42%). Ophthalmo-neurologic symptoms were the presenting symptoms of 11% of the new cases. The majority of cases (75%) presented at stage III/IV.
  9. Chai SJ, Pua KC, Saleh A, Yap YY, Lim PV, Subramaniam SK, et al.
    J Clin Virol, 2012 Sep;55(1):34-9.
    PMID: 22739102 DOI: 10.1016/j.jcv.2012.05.017
    Nasopharyngeal carcinoma (NPC) is an Epstein-Barr Virus (EBV)-associated cancer that is the fifth most common cancer in Malaysia. Early and accurate diagnoses are critical for patient prognosis. Unfortunately, early detection of NPC is still a challenge and the cost of more accurate imaging protocols is prohibitive in developing countries like Malaysia.
  10. Yap LF, Lai SL, Rhodes A, Sathasivam HP, Abdullah MA, Pua KC, et al.
    Infect Agent Cancer, 2018;13:21.
    PMID: 29942347 DOI: 10.1186/s13027-018-0193-6
    Background: The incidence of oropharyngeal squamous cell carcinoma (OPSCC) has been rising in Western countries and this has been attributed to human papillomavirus (HPV) infection. p16 expression is a marker for HPV infection and p16 positive OPSCC is now recognized as a separate disease entity. There are only limited data available regarding HPV-related OPSCC in Asian countries and no data from Malaysia.

    Methods: We identified 60 Malaysian patients with OPSCC over a 12-year period (2004-2015) from four different hospitals in two major cities, Kuala Lumpur and Penang. The detection of HPV was carried out using p16 immunohistochemistry and high risk HPV DNA in situ hybridisation.

    Results: Overall, 15 (25%) tumours were p16 positive by immunohistochemistry, 10 of which were also positive for high risk HPV DNA by in situ hybridisation. By comparison, a matched cohort of UK patients had a p16 positive rate of 49%. However, between 2009 and 2015, where cases were available from all four hospitals, 13 of 37 (35%) cases were p16 positive. In our Malaysian cohort, 53% of patients were of Chinese ethnicity and 80% of the p16 positive cases were found in these patients; no Indian patients had p16 positive disease, despite representing 35% of the total cohort.

    Conclusion: The proportion of OPSCCs associated with HPV in Malaysia appears to be lower than in European and American cohorts and could possibly be more prevalent amongst Malaysians of Chinese ethnicity. Further, our data suggests that the burden of HPV-related OPSCC could be increasing in Malaysia. Larger cross-sectional studies of Malaysian patients are required to determine the public health implications of these preliminary findings.

  11. Low JS, Chin YM, Mushiroda T, Kubo M, Govindasamy GK, Pua KC, et al.
    PLoS One, 2016;11(1):e0145774.
    PMID: 26730743 DOI: 10.1371/journal.pone.0145774
    BACKGROUND: Nasopharyngeal carcinoma (NPC) is a neoplasm of the epithelial lining of the nasopharynx. Despite various reports linking genomic variants to NPC predisposition, very few reports were done on copy number variations (CNV). CNV is an inherent structural variation that has been found to be involved in cancer predisposition.

    METHODS: A discovery cohort of Malaysian Chinese descent (NPC patients, n = 140; Healthy controls, n = 256) were genotyped using Illumina® HumanOmniExpress BeadChip. PennCNV and cnvPartition calling algorithms were applied for CNV calling. Taqman CNV assays and digital PCR were used to validate CNV calls and replicate candidate copy number variant region (CNVR) associations in a follow-up Malaysian Chinese (NPC cases, n = 465; and Healthy controls, n = 677) and Malay cohort (NPC cases, n = 114; Healthy controls, n = 124).

    RESULTS: Six putative CNVRs overlapping GRM5, MICA/HCP5/HCG26, LILRB3/LILRA6, DPY19L2, RNase3/RNase2 and GOLPH3 genes were jointly identified by PennCNV and cnvPartition. CNVs overlapping GRM5 and MICA/HCP5/HCG26 were subjected to further validation by Taqman CNV assays and digital PCR. Combined analysis in Malaysian Chinese cohort revealed a strong association at CNVR on chromosome 11q14.3 (Pcombined = 1.54x10-5; odds ratio (OR) = 7.27; 95% CI = 2.96-17.88) overlapping GRM5 and a suggestive association at CNVR on chromosome 6p21.3 (Pcombined = 1.29x10-3; OR = 4.21; 95% CI = 1.75-10.11) overlapping MICA/HCP5/HCG26 genes.

    CONCLUSION: Our results demonstrated the association of CNVs towards NPC susceptibility, implicating a possible role of CNVs in NPC development.

  12. Chin YM, Mushiroda T, Takahashi A, Kubo M, Krishnan G, Yap LF, et al.
    Int J Cancer, 2015 Feb 1;136(3):678-87.
    PMID: 24947555 DOI: 10.1002/ijc.29035
    Nasopharyngeal carcinoma (NPC) arises from the mucosal epithelium of the nasopharynx and is constantly associated with Epstein-Barr virus type 1 (EBV-1) infection. We carried out a genome-wide association study (GWAS) of 575,247 autosomal SNPs in 184 NPC patients and 236 healthy controls of Malaysian Chinese ethnicity. Potential association signals were replicated in a separate cohort of 260 NPC patients and 245 healthy controls. We confirmed the association of HLA-A to NPC with the strongest signal detected in rs3869062 (p = 1.73 × 10(-9)). HLA-A fine mapping revealed associations in the amino acid variants as well as its corresponding SNPs in the antigen peptide binding groove (p(HLA-A-aa-site-99) = 3.79 × 10(-8), p(rs1136697) = 3.79 × 10(-8)) and T-cell receptor binding site (p(HLA-A-aa-site-145) = 1.41 × 10(-4), p(rs1059520) = 1.41 × 10(-4)) of the HLA-A. We also detected strong association signals in the 5'-UTR region with predicted active promoter states (p(rs41545520) = 7.91 × 10(-8)). SNP rs41545520 is a potential binding site for repressor ATF3, with increased binding affinity for rs41545520-G correlated with reduced HLA-A expression. Multivariate logistic regression diminished the effects of HLA-A amino acid variants and SNPs, indicating a correlation with the effects of HLA-A*11:01, and to a lesser extent HLA-A*02:07. We report the strong genetic influence of HLA-A on NPC susceptibility in the Malaysian Chinese.
  13. Chin YM, Tan LP, Abdul Aziz N, Mushiroda T, Kubo M, Mohd Kornain NK, et al.
    Int J Cancer, 2016 10 15;139(8):1731-9.
    PMID: 27236004 DOI: 10.1002/ijc.30207
    Nasopharyngeal carcinoma (NPC) is an epithelial squamous cell carcinoma on the mucosal lining of the nasopharynx. The etiology of NPC remains elusive despite many reported studies. Most studies employ a single platform approach, neglecting the cumulative influence of both the genome and transcriptome toward NPC development. We aim to employ an integrated pathway approach to identify dysregulated pathways linked to NPC. Our approach combines imputation NPC GWAS data from a Malaysian cohort as well as published expression data GSE12452 from both NPC and non-NPC nasopharynx tissues. Pathway association for GWAS data was performed using MAGENTA while for expression data, GSA-SNP was used with gene p values derived from differential expression values from GEO2R. Our study identified NPC association in the gene ontology (GO) axonemal dynein complex pathway (pGWAS-GSEA  = 1.98 × 10(-2) ; pExpr-GSEA  = 1.27 × 10(-24) ; pBonf-Combined  = 4.15 × 10(-21) ). This association was replicated in a separate cohort using gene expression data from NPC and non-NPC nasopharynx tissues (pAmpliSeq-GSEA  = 6.56 × 10(-4) ). Loss of function in the axonemal dynein complex causes impaired cilia function, leading to poor mucociliary clearance and subsequently upper or lower respiratory tract infection, the former of which includes the nasopharynx. Our approach illustrates the potential use of integrated pathway analysis in detecting gene sets involved in the development of NPC in the Malaysian cohort.
  14. Yew PY, Mushiroda T, Kiyotani K, Govindasamy GK, Yap LF, Teo SH, et al.
    Mol Carcinog, 2012 Oct;51 Suppl 1:E74-82.
    PMID: 22213098 DOI: 10.1002/mc.21857
    Nasopharyngeal carcinoma (NPC) is a multifactorial and polygenic disease with high incidence in Asian countries. Epstein-Barr virus infection, environmental and genetic factors are believed to be involved in the tumorigenesis of NPC. The association of single nucleotide polymorphisms (SNPs) in LPLUNC1 and SPLUNC1 genes with NPC was investigated by performing a two-stage case control association study in a Malaysian Chinese population. The initial screening consisted of 81 NPC patients and 147 healthy controls while the replication study consisted of 366 NPC patients and 340 healthy controls. The combined analysis showed that a SNP (rs2752903) of SPLUNC1 was significantly associated with the risk of NPC (combined P = 0.00032, odds ratio = 1.62, 95% confidence interval = 1.25-2.11). In the subsequent dense fine mapping of SPLUNC1 locus, 36 SNPs in strong linkage disequilibrium with rs2752903 (r(2) ≥ 0.85) were associated with NPC susceptibility. Screening of these variants by electrophoretic mobility shift and luciferase reporter assays showed that rs1407019 located in intron 3 (r(2)  = 0.994 with rs2752903) caused allelic difference in the binding of specificity protein 1 (Sp1) transcription factor and affected luciferase activity. This SNP may consequently alter the expression of SPLUNC1 in the epithelial cells. In summary, our study suggested that rs1407019 in intronic enhancer of SPLUNC1 is associated with NPC susceptibility in which its A allele confers an increased risk of NPC in the Malaysian Chinese population.
  15. Chow YP, Tan LP, Chai SJ, Abdul Aziz N, Choo SW, Lim PV, et al.
    Sci Rep, 2017 03 03;7:42980.
    PMID: 28256603 DOI: 10.1038/srep42980
    In this study, we first performed whole exome sequencing of DNA from 10 untreated and clinically annotated fresh frozen nasopharyngeal carcinoma (NPC) biopsies and matched bloods to identify somatically mutated genes that may be amenable to targeted therapeutic strategies. We identified a total of 323 mutations which were either non-synonymous (n = 238) or synonymous (n = 85). Furthermore, our analysis revealed genes in key cancer pathways (DNA repair, cell cycle regulation, apoptosis, immune response, lipid signaling) were mutated, of which those in the lipid-signaling pathway were the most enriched. We next extended our analysis on a prioritized sub-set of 37 mutated genes plus top 5 mutated cancer genes listed in COSMIC using a custom designed HaloPlex target enrichment panel with an additional 88 NPC samples. Our analysis identified 160 additional non-synonymous mutations in 37/42 genes in 66/88 samples. Of these, 99/160 mutations within potentially druggable pathways were further selected for validation. Sanger sequencing revealed that 77/99 variants were true positives, giving an accuracy of 78%. Taken together, our study indicated that ~72% (n = 71/98) of NPC samples harbored mutations in one of the four cancer pathways (EGFR-PI3K-Akt-mTOR, NOTCH, NF-κB, DNA repair) which may be potentially useful as predictive biomarkers of response to matched targeted therapies.
  16. Chai SJ, Fong SCY, Gan CP, Pua KC, Lim PVH, Lau SH, et al.
    Hum Vaccin Immunother, 2019;15(1):167-178.
    PMID: 30193086 DOI: 10.1080/21645515.2018.1520584
    Peptide vaccines derived from tumour-associated antigens have been used as an immunotherapeutic approach to induce specific cytotoxic immune response against tumour. We previously identified that MAGED4B and FJX1 proteins are overexpressed in HNSCC patients; and further demonstrated that two HLA-A2-restricted 9-11 amino acid peptides derived from these proteins were able to induce anti-tumour immune responses in vitro independently using PBMCs isolated from these patients. In this study, we evaluated the immunogenicity and efficacy of a dual-antigenic peptide vaccine (PV1), comprised of MAGED4B and FJX1 peptides in HNSCC patients. We first demonstrated that 94.8% of HNSCC patients expressed MAGED4B and/or FJX1 by immunohistochemistry, suggesting that PV1 could benefit the majority of HNSCC patients. The presence of pre-existing MAGED4B and FJX1-specific T-cells was detected using a HLA-A2 dimer assay and efficacy of PV1 to induce T-cell to secrete cytotoxic cytokine was evaluated using ELISPOT assay. Pre-existing PV1-specific T-cells were detected in all patients. Notably, we demonstrated that patients' T-cells were able to secrete cytotoxic cytokines upon exposure to target cells expressing the respective antigen post PV1 stimulation. Furthermore, patients with high expression of MAGED4B and FJX1 in their tumours were more responsive to PV1 stimulation, demonstrating the specificity of the PV1 peptide vaccine. Additionally, we also demonstrated the expression of MAGED4B and FJX1 in breast, lung, colon, prostate and rectal cancer suggesting the potential use of PV1 in these cancers. In summary, PV1 could be a good vaccine candidate for the treatment of HNSCC patients and other cancers expressing these antigens.
  17. Sathasivam HP, Chew SYL, Kim WR, Saw CL, Tan LP, Tengku Din TADA, et al.
    Clin Otolaryngol, 2022 Feb 16.
    PMID: 35170855 DOI: 10.1111/coa.13917
    1. Majority of adolescent nasopharyngeal carcinoma (NPC) patients present with advanced locoregional disease. 2. The ethnic distribution of patients with adolescent NPC could be different from that of adult NPC suggesting a possible difference in aetiopathogenesis. 3. The late presentation of adolescent NPC underlies the importance of recognizing the clinical presentation and characteristics of this cancer.
  18. Tan LP, Tan GW, Sivanesan VM, Goh SL, Ng XJ, Lim CS, et al.
    Int J Cancer, 2020 04 15;146(8):2336-2347.
    PMID: 31469434 DOI: 10.1002/ijc.32656
    Nasopharyngeal carcinoma (NPC) is originated from the epithelial cells of nasopharynx, Epstein-Barr virus (EBV)-associated and has the highest incidence and mortality rates in Southeast Asia. Late presentation is a common issue and early detection could be the key to reduce the disease burden. Sensitivity of plasma EBV DNA, an established NPC biomarker, for Stage I NPC is controversial. Most newly reported NPC biomarkers have neither been externally validated nor compared to the established ones. This causes difficulty in planning for cost-effective early detection strategies. Our study systematically evaluated six established and four new biomarkers in NPC cases, population controls and hospital controls. We showed that BamHI-W 76 bp remains the most sensitive plasma biomarker, with 96.7% (29/30), 96.7% (58/60) and 97.4% (226/232) sensitivity to detect Stage I, early stage and all NPC, respectively. Its specificity was 94.2% (113/120) against population controls and 90.4% (113/125) against hospital controls. Diagnostic accuracy of BamHI-W 121 bp and ebv-miR-BART7-3p were validated. Hsa-miR-29a-3p and hsa-miR-103a-3p were not, possibly due to lower number of advanced stage NPC cases included in this subset. Decision tree modeling suggested that combination of BamHI-W 76 bp and VCA IgA or EA IgG may increase the specificity or sensitivity to detect NPC. EBNA1 99 bp could identify NPC patients with poor prognosis in early and advanced stage NPC. Our findings provided evidence for improvement in NPC screening strategies, covering considerations of opportunistic screening, combining biomarkers to increase sensitivity or specificity and testing biomarkers from single sampled specimen to avoid logistic problems of resampling.
  19. Bei JX, Su WH, Ng CC, Yu K, Chin YM, Lou PJ, et al.
    Cancer Epidemiol Biomarkers Prev, 2016 Jan;25(1):188-192.
    PMID: 26545403 DOI: 10.1158/1055-9965.EPI-15-0144
    BACKGROUND: Genetic loci within the major histocompatibility complex (MHC) have been associated with nasopharyngeal carcinoma (NPC), an Epstein-Barr virus (EBV)-associated cancer, in several GWAS. Results outside this region have varied.

    METHODS: We conducted a meta-analysis of four NPC GWAS among Chinese individuals (2,152 cases; 3,740 controls). Forty-three noteworthy findings outside the MHC region were identified and targeted for replication in a pooled analysis of four independent case-control studies across three regions in Asia (4,716 cases; 5,379 controls). A meta-analysis that combined results from the initial GWA and replication studies was performed.

    RESULTS: In the combined meta-analysis, rs31489, located within the CLPTM1L/TERT region on chromosome 5p15.33, was strongly associated with NPC (OR = 0.81; P value 6.3 × 10(-13)). Our results also provide support for associations reported from published NPC GWAS-rs6774494 (P = 1.5 × 10(-12); located in the MECOM gene region), rs9510787 (P = 5.0 × 10(-10); located in the TNFRSF19 gene region), and rs1412829/rs4977756/rs1063192 (P = 2.8 × 10(-8), P = 7.0 × 10(-7), and P = 8.4 × 10(-7), respectively; located in the CDKN2A/B gene region).

    CONCLUSIONS: We have identified a novel association between genetic variation in the CLPTM1L/TERT region and NPC. Supporting our finding, rs31489 and other SNPs in this region have been reported to be associated with multiple cancer sites, candidate-based studies have reported associations between polymorphisms in this region and NPC, the TERT gene has been shown to be important for telomere maintenance and has been reported to be overexpressed in NPC, and an EBV protein expressed in NPC (LMP1) has been reported to modulate TERT expression/telomerase activity.

    IMPACT: Our finding suggests that factors involved in telomere length maintenance are involved in NPC pathogenesis.

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