Prevalence of human papilloma virus in laryngeal cancers.

Philip, George (2014) Prevalence of human papilloma virus in laryngeal cancers. Masters thesis, Christian Medical College, Vellore.


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OBJECTIVES : To find out the prevalence of Human Papilloma virus in laryngeal cancers in the ENT Department of a tertiary level teaching hospital. METHODS : The study was conducted in the ENT outpatient department and in the ENT operating room at Christian Medical College,Vellore between November 2011 and July 2013. Study included 30 cases of laryngeal cancers and 30 controls which were benign lesions of vocal cords such as polyps,cysts or nodules.Cases and controls were evaluated in the ENT outpatient department and explained about the study in detail and were given an information sheet for clarifications. Informed valid consent was taken.Tissue was taken for the study when patient was posted for a direct laryngoscopic/microlaryngoscopic biopsy of the lesion. Tissue is taken for histopathological examination as well as HPV study.The tissue obtained is transferred to a VTM tube,i.e viral transport medium tube and is taken to the virology lab in an ice container. Viral transport medium is a balanced isotonic solution at physiological pH. It maintains the virus in the viable state.It contains fetal calf serum and antibiotics. Once received in lab, the samples were transferred from the VTM tube to a 1.5ml eppendorf tube and stored at -800C until further testing in -80 degree freezer.The next step is DNA extraction using DNA extraction kit, DNeasy® Tissue kit: (Qiagen GmbH, Hilden, Germany). The extracted DNA undergoes Polymerase chain reaction.A known positive control was used for PCR and beta-globin serves as internal control. If sample was positive for HPV,sequencing is done to identify the genotype.The amplified PCR products were purified by Millipore filtration and sequenced directly using an ABI Prism Big Dye terminator cycle sequencing ready reaction kit. Finally, the data was analyzed using Bioedit software version and study sequences compared to the GenBank HPV sequences. WHO recommended CHUV assay had to be used in case of 2 samples which were not able to be sequenced using routine methods From the previous studies in the literature the average prevalence of HPV in laryngeal carcinoma is 25%. n=2pq(Zα + Zβ)2/(P1-Po)2 By applying the formula n=73 Hence,in each arm 73 cases should be studied. But the average number of microlaryngoscopy for cases of laryngeal cancers in CMC is 3-4 per month. Hence the aim was to study 30 cases and 30 controls. RESULTS : Out of the 30 cases of laryngeal squamous cell carcinoma cases,4 were positive for HPV whereas there were no positive HPV cases in the control group. One was HPV 16 type and another one HPV 11 type. Two other positive cases were not able to be sequenced probably due to low viral load. The results of HPV in laryngeal cancers were statistically insignificant with a p value of 0.052.Our study showed that both smoking and tobacco chewing had 5 times increased risk of acquiring laryngeal cancers. CONCLUSION : As there were 4 HPV positive cases in the cancer group whereas there were none in the control group, there is more trend towards HPV positivity in the cancer group.Further studies are essential to prove the confirmatory role of HPV in laryngeal cancers HPV subtyping needs to be done for all juvenile and adult-onset laryngeal papillomatosis in view of chances of malignant transformation. These patients need to be followed up regularly. HPV testing should be made mandatory in the workup of laryngeal cancer patients especially in young patients without any co-existing risk habits such as smoking ,tobacco chewing and alcohol consumption.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Human papilloma virus; laryngeal cancer
Subjects: MEDICAL > Otolaryngology
Depositing User: Devi S
Date Deposited: 13 Jul 2017 10:23
Last Modified: 13 Jul 2017 10:23

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