Hassan, Shahid and Yap, Yap and Ravichandran, M. and Chan, Melissa Li-Ann
(2006)
Diagnosis of nasopharyngeal carcinoma by DNA amplification of
epstein-bar virus genomes in tissue obtained by biopsy and fine-needle aspiration.
Diagnosis of nasopharyngeal carcinoma by DNA amplification of epstein-bar virus genomes in tissue obtained by biopsy and fine-needle aspiration.
(Submitted)
Abstract
Background
Penemuan Projek/Abstrak
(Perfu disediakan makluman di antara 100 - 200 perkataan di dalam Bahasa Malaysia dan Bahasa
lnggeris. lni kemudiannya akan dimuatkan ke dalam Laporan Tahunan Sahagian Penyefidikan &
Pembangunan sebagai satu cara untuk menyampaikan dapatan projek tuanfpu~n kepada pihak
Universiti).
(English version)
Nasopharyngeal carcinoma (NPC) is common in Malaysia but diagnosis is sometimes delayed for
non-representative biopsy, submucosal disease and occult primaries- increasing m·arbidity and
mortality. Epstein-Barr virus (EBV) is associated with all types of NPC and DNA in tumor cells is
detectable by polymerase chain reaction (PCR). EBV products EBNA 1, EBNA2 and LMP1 are
implicated in oncogenesis and is detectable in nodal tissue. However no similar study has been
done in Southeast-Asia with adequate sample.
Objectives
This study evaluates the validity and reliability of detecting EBV genes in biopsy and FNAC tissue
in NPC by PCR.
Methodology
Tissue from 72 nasopharyngeal biopsies were collected from consented patients. 36 were
positive and 36 negatives served as controls. Tissue from 70 fine-needle aspirations were
similarly obtained. 35 belonged to NPC-positive patients, and 35 of other pathologies served as
controls.
DNA was extracted, amplified with forward and reverse primers for EBNA 1, EBNA2, LMP1 genes
and human a-actin gene as control, and detected by electrophoresis. Cloned DNA from 895-8
cell line served as positive control.
Histopathological-proven primary tumour and clinico-pathological criteria for neck nodes (clinically
suspicious neck node with histopathologically-confirmed primary tumour) were used as gold
standard.
Results
35/36 positive nasopharyngeal biopsies and 35/36 negatives contained sufficient DNA. EBNA 1
gene was detected in 34/35 positive specimens but were undetected in the controls. EBNA2 gene
was detected in 31/35 positive specimens and in 2/35 controls. LMP1 was detected in 32/35
positive specimens and in 4/35 controls. (P > 0.05 by McNemar_s test-- i.e. no significant
difference from histopathology.) EBNA1 has the best sensitivity (97.1%) and specificity (100%)
(Kappa = 0.97). One patient in the control group was positive for EBV DNA and developed NPC
1 year later. Another patient with obvious nasopharyngeal tumour was negative on the 1st biopsy
and confirmed on repeat biopsy 2 weeks later, but EBV DNA was detected in ~oth specimens.
35/36 metastatic NPC specimens contained sufficient DNA and one was excluded due to
presence of second primary. EBNA 1 gene was detected in 30/34 nodes and 1/34 rontro1s.
EBNA2 gene was detected in 29/34 nodes and none of the controls. LMP1 gene was detected in
30/34 nodes and in 2134 of controls. (P > 0.05 by McNemar_s test_ i.e. no significant difference
from clinico-pathological criteria for neck metastasis). A cut-off point of >0/3 genes offers the
highest sensitivity (97.1%} and specificity (94.1%) (Kappa= 0.91 ).
All histological types of NPC contained EBV DNA.
Conclusion
EBV DNA detection is reliable and a~rate in di~gnosing NPC. On par with histopathology in
detecting primary tumours, it ~lso predtcts.the dev~l?pment ?f NPC. On par with clinicopathological
criteria in detecting metastatic NPC, 1t IS supenor to fine-needle cytology and can
suggest NPC in occult primaries
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