Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 14  |  Issue : 2  |  Page : 107-113

Emerging Trend of Oral and Oropharyngeal Squamous Cell Carcinoma in Patients Less than 40 Years: A Molecular Analysis of Role of HPV in Cases with No Known Risk Factors


1 Department of Oral Pathology and Microbiology, JSS Dental College & Hospital, JSS AHER, Mysuru, India
2 Department of Pathology, JSS Medical College, JSS AHER, Mysuru, India

Date of Submission09-Mar-2022
Date of Decision07-Oct-2022
Date of Acceptance20-Oct-2022
Date of Web Publication10-Jan-2023

Correspondence Address:
Dr. Usha Hegde
Department of Oral Pathology and Microbiology, JSS Dental College & Hospital, Mysuru, 570015
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jofs.jofs_72_22

Rights and Permissions
  Abstract 


Introduction: Traditional risk factors causing oral and oropharyngeal cancers have been extensively studied in elderly populations. But recent evidences have shown it to be rising in young individuals with no known risk factors. Human Papilloma virus (HPV) is a proven etiologic factor for cervical cancer and has been suggested in oral squamous cell carcinoma (OSCC) and oropharyngeal squamous cell carcinoma (OPSCC). Hence the objective of the study was to evaluate the role of HPV as a risk factor in OSCC and OPSCC patients of less than 40 years of age without known risk factors. Material and Methods: Fifteen years of retrospective data were used for recording the age, gender, site, and various risk factors in patients ≤40 years of age diagnosed histopathologically with primary OSCC and OPSCC. Role of HPV in patients without any known risk factors were evaluated with p16 Immunohistochemistry (IHC) and polymerase chain reaction (PCR). Results: Ninety eight patients aged ≤40 years of age were obtained with known and no known risk factors. Among the habitual risk factors, alcohol did not prove to be a significant factor. Female patients with mean age of 34 years were more prone, though they were not subjected to any of the known risk factors. Tongue and buccal mucosa were the most common sites affected. Role of HPV as a risk factor was found positive. All cases of PCR positive were IHC positive and IHC showed 100% sensitivity and 68.4% specificity. Conclusion: A strong correlation of HPV with OSCC and OPSCC in adults ≤40 years of age was established in the present study.

Keywords: Human Papilloma virus, oral squamous cell carcinoma (OSCC), oropharyngeal squamous cell carcinoma (OPSCC), p16, polymerase chain reaction, South Indian population, young


How to cite this article:
Nair P, Hegde U, Sheshanna SH, Ravi S. Emerging Trend of Oral and Oropharyngeal Squamous Cell Carcinoma in Patients Less than 40 Years: A Molecular Analysis of Role of HPV in Cases with No Known Risk Factors. J Orofac Sci 2022;14:107-13

How to cite this URL:
Nair P, Hegde U, Sheshanna SH, Ravi S. Emerging Trend of Oral and Oropharyngeal Squamous Cell Carcinoma in Patients Less than 40 Years: A Molecular Analysis of Role of HPV in Cases with No Known Risk Factors. J Orofac Sci [serial online] 2022 [cited 2023 Jan 28];14:107-13. Available from: https://www.jofs.in/text.asp?2022/14/2/107/367449




  Introduction Top


In 1959, Dalitsch and Vazirami examined increasing incidence of oral cancer and stated “The disease of our century is cancer.”[1] Oral cancer remains a fatal and constant problem which accounts for 4% of cancers worldwide.[2] It is the fifth most common cancer globally.[3] Markedly higher prevalence of oral cancer is found in some Asian populations, mainly in South Asian countries including India and Pakistan.[4] Squamous cell carcinoma (SCC) accounts for more than 90% of oral cancers.[5] Oral cancer is rare in young patients and has reached an incidence of 0.4% to 3.6% in patients younger than 40 years.[6] The recent evidence suggests an absence of traditional factors in a significant proportion of younger patients. Moreover, the time span for carcinogens such as tobacco and alcohol to exert a detrimental effect in these younger patients is relatively short. It is also important to examine other potential risk factors, such as environmental carcinogens, stress, previous viral infections, and familial episodes of cancer.[7] Some studies have suggested that these patients may exhibit a predisposition to genetic instability.[8]

Young adults most commonly develop primary tumor in oropharynx and oral cavity and less frequently in the larynx compared to older patients.[9],[10] It has even been suggested that oral cancer in the young may be a disease distinct from that occurring in older patients with a different etiology and disease progression.[7]

Human Papilloma viruses (HPV), members of the papillomaviridae family, consists of more than 100 types which are further categorized into low-risk (LR) and high-risk (HR) types according to their potential for causing SCC.[11] Examples of LR-HPV genotypes are HPV-6, 11, 42, 43, 44 and of HR-HPV genotypes are HPV-16, 18, 31, 33, 35, 45, 51, 52, 56, 58, and 59.[12]

Over the past 15 years, HPV, the necessary cause of cancer of the cervix,[13] has also been etiologically linked with a subset of head and neck squamous cell carcinomas (HNSCC). Some of the high-risk types have been found in the oral cavity and oropharynx of cancer-free adults and in cancer biopsy specimens from HNSCC patients. HPV16, the most prevalent HPV type in cervical SCCs, is also the most common type present in HPV-positive HNSCCs.[14] In the absence of any known risk factors, HPV has been consistently implied as a causative element in recently emerging evidences.[15] It is time to focus on the prevention and early detection for the survival of young people who form a huge part of the future of the nation. Hence, the present study was undertaken to evaluate the different risk factors causing oral squamous cell carcinoma (OSCC) and oropharyngeal squamous cell carcinoma (OPSCC) in young adults ≤40 years of age and also to assess the association of HPV in those patients without any known risk factors.


  Material and Methods Top


Ethical approval for this study (Ethical committee Ref No: JSS/ACP/Ethical/2012-13) was provided by the Institutional Ethical Committee of JSS Dental College & Hospital, Mysuru, on January 31, 2013. Fifteen years of retrospective data from records of patients ≤40 years of age diagnosed with primary OSCC and OPSCC from our institution were taken. The study group was divided into two groups − group 1: Cases with known risk factors and group 2: Cases with no known risk factors. As the pathophysiologic behavior of lip cancer is believed to be substantially different from the oral cavity sites, cancers originating in the lip were not included in the study. Cases with underlying immunocompromised conditions and cases with metastasis to oral and oropharyngeal areas from other sites were excluded.

All details were studied carefully and the age, gender, site, and various risk factors implicated in OSCC and OPSCC were recorded. Formalin fixed paraffin embedded (FFPE) samples from group 2 were further taken and p16 Immunohistochemistry (IHC) marker and polymerase chain reaction (PCR) were performed.

HPV screening

5-µm thick sections from FFPE blocks were cut and mounted on poly-l-lysine coated slides. IHC staining was carried out using polymer labeling technique. Sections were dewaxed, washed in alcohol, and antigen retrieval was carried out in pressure cooker with 10 mM citrate buffer solution for 15 minutes. Endogenous peroxidase was blocked by using 0.3% hydrogen peroxide in methanol at room temperature for 10 minutes. Slides were washed twice with Tris buffer (TBS) briefly and incubated with primary antibody (Biogenex − Anti-p16[INK 4], monoclonal, anti-mouse) for 60 minutes. Sections were washed with phosphate buffer solution (PBS) and incubated with the secondary antibodies for 30 minutes. Sections were then washed with PBS and DAB was used as the chromogen solution in hydrogen peroxide for 10 minutes. Sections were then counterstained with hematoxylin and studied. The sections were considered positive if cytoplasm of tumor cells was stained brown, excluding the cells surrounding the blood vessel.

HPV detection

Detection of HPV was done using DNA amplification with Consensus Primers. Twenty μm slice of paraffin wax embedded tissue was collected, dewaxed, and then rehydrated. After rehydration, samples were digested with proteinase K (20 mg/mL) at 55°C for 1 to 3 hours. Total genomic DNA from the retrieved tissue was isolated by N-Cetyl- N, N, N-trimethyl-ammonium bromide (CTAB) method using extraction buffer. Once the quality and quantity of DNA was checked the samples were further considered for further PCR analysis with HPV 16 designed using Primer3 Plus software and the designed oligonucleotides synthesized in Sigma Corporation USA. PCR reaction mixture and PCR temperature profiling prior to Agarose gel electrophoresis was done. Once the sample was run sufficiently, the gel was removed using gloves and visualized under UV light, photographed and documented using UV trans-illuminator.

Descriptive statistics, mean and standard deviation was done to assess age, site, and gender. Chi-square test was done to find the association between risk of developing cancer and other variables used in the study. Chi-square test was also used to test the difference between negative and positive cases of IHC and PCR and also to find an association between IHC and PCR methods, independent “t” test to analyze the difference between both groups (group 1 and group 2) and mean age, one way Analysis of variance (ANOVA) to compare mean age with groups (group 1 and group 2) and gender.


  Results Top


From the 15 years of retrospective data obtained from the records, a total of 98 cases of ≤40 years of age, diagnosed with primary OSCC and OPSCC were obtained based on the inclusion and exclusion criteria considered in this study. The age, gender, and site of lesion were available for all cases. However, the detailed history regarding the risk factors/tobacco habits were unavailable for 26 cases. Though all cases could be subjected to statistical analysis with respect to age, gender, and site, only 72 cases could be assessed for known risk factors of which 40 cases gave a history of known risk factors and 32 did not. On statistical analysis we found that from the overall sample of 98 cases, mean age was 36.28 ± 4.58 years with mean age of males and females being 36.84 ± 2.99 and 35.81 ± 5.58 years, respectively. Though statistical significance was not drawn with respect to gender, more number of cases were recorded in females compared to that of males. Most common site affected was tongue followed by buccal mucosa and these results were statistically significant.

When group 1 and 2 were analyzed separately, the mean age recorded was statistically significant [Table 1] with increased risk seen with advancing age. With regard to gender and site [Table 2] and [Table 3] respectively], no significant results were drawn except in group 1 with regard to gender, 71.9% males had chance to develop cancer when exposed to known risk factors. There is a thin line of difference in the site predilection between tongue and buccal mucosa in both the groups. Strong correlation was obtained with tobacco, smoking, and arecanut [Table 4], but not with alcohol habituers [Table 5] or with synergistic effects of tobacco, alcohol, and smoking.
Table 1 Table showing mean age with gender (group 1 and 2)

Click here to view
Table 2 Table depicting gender predilection (group 1 and 2)

Click here to view
Table 3 Table showing site predilection (group 1 and 2)

Click here to view
Table 4 Table showing comparison of significant habits and risk of developing cancer

Click here to view
Table 5 Table showing comparison of alcohol and risk of developing cancer

Click here to view


For performing IHC and PCR, 25 cases were chosen from group 2 (FFPE blocks were not available for two cases and insufficient amplification was noted in five cases). On IHC, 13 samples were positive and on PCR, six samples were positive with 850 bp amplicon. On statistical analysis, PCR showed statistical significance (P value = 0.009) but IHC did not (P value = 0.715). Statistical significance was found between IHC and PCR comparison [Table 6]. In IHC 48% cases were positive as against only 24% in PCR, implying low specificity with IHC.
Table 6 Table showing association of IHC and PCR

Click here to view



  Discussion Top


Though OSCC has a worldwide increase in incidence and mortality, variations do occur in respect to the demographics or lifestyle and habits within different populations. Higher prevalence is consistently found in some Asian populations, mainly in South Asian countries including India, Pakistan, Srilanka, and Bangladesh.[16] Although it is known that HNSCCs usually occurs in patients older than sixth decade of life, incidence is rising in younger age groups and have been reported from different parts of the world. Among them, there is a subgroup of population who reported little or no exposure to the major risk factors.[17] Also there is rising incidence of OPSCC in the absence of rise in smoking and alcohol consumption.[18] These led to the search for additional analytical data on risk factors in such younger age group patients. HPV, a known cause of cervical cancer, has been studied extensively as a strong etiological factor for development of OSCC and OPSCC. In the present study, from the data available, only a marginal difference was found in the number of cases with known risk factors and without risk factors (group 1 and 2) indicating emerging rise in development of cancer in young individuals without prior habitual or personal history.

The mean age of patients ≤40 years of age among both the genders in group 1 and 2 was in the range of 34 to 37 years. The mean female age with no risk factors was 34 years which makes young women in the middle age to be more prone to SCC inspite of no personal or habitual history. Age average in cases registered in literature as young bearers of SCC ranges from 30.8 to 34.2 years.[19] Studies in Taiwan and Northern Thailand showed mean ages to be 36 and 39 years respectively.[8],[20] In the present study, males and females had a risk of 28.1% and 57.5% to develop SCC with females to be at a higher risk in group 2. In group 1, men were affected more than females which had a correlation to numerous studies.[21],[22]

With regard to site, previous studies have shown a predilection between tongue[8],[10],[23],[24] and buccal mucosa.[8],[21] Countries like USA, Australia, Brazil, and Denmark reported tongue to be the most common site.[25],[26] On the contrary, other Asian countries such as Taiwan, Malaysia, Papua New Guinea, Bangladesh, and India have found that buccal mucosa was the most common location.[27],[28],[29] But in the young, OSCC of the buccal mucosa was rare, possibly because of the reducing habit in this age group, while the older population continues to practise the habit.[30] Our study showed tongue and buccal mucosa to be the most common sites in both group 1 and group 2. Buccal mucosa was more affected than tongue in the group 1, but was vice versa in group 2. In group 2, though number of cases was equal in tongue and buccal mucosa, tongue had 57.1% chances of developing SCC compared to buccal mucosa which was 36.4%.

Various risk factors like tobacco,[31],[32] smoking,[33] arecanut,[34],[35] and alcohol[36],[37] have been extensively studied. A definite correlation of these factors with OSCC and OPSCC has been established. In our study, significant results were obtained with risk factors such as chewable tobacco, smoking, and arecanut. Results were not significant in cases of alcohol and other synergistic effects with tobacco, alcohol, and smoking.

In a review on risk factors in young people, Llewellyn et al. have discussed in detail regarding the other risk factors like occupation, immune defence, viral infection, diet, genetic, and familial factors.[6] Studies have been done on anemia[38] and trauma[39] as risk factors of oral cancers. An inverse association between coffee and cancer risk have also found plausible biological support, since coffee beans contain several phenolic compounds with antioxidant properties, such as caffeic acid and chlorogenic acid.[40] In the present study, inspite of thoroughly checking the data available, no other risk factors were reported.

Different methods have been employed for the detection of HPV.[41],[42] Numerous studies have been done using p16 IHC and PCR for detection of HPV in tissues.[43],[44],[45],[46] Most studies were done in the past on association of HPV with OPSCC,[47],[48],[49],[50],[51],[52] but in our study, most cases belonged to the oral rather than oropharyngeal SCCs as those diagnosed of OPSCC were most with habitual history or relevant case sheets were missing to record the known risk factors and could not be considered for further study.

Pannone et al. conducted a study to demonstrate the reliability of triple method applied to detect HPV in HNSCC originating from OSCC and OPSCC using p16 IHC, in-situ hybridization (ISH), and consensus PCR. All the HNSCCs confirmed HPV positive by PCR and/or ISH were also p16 positive by IHC. The IHC results showed a very high level of sensitivity (100% in both OSCC and OPSCC) but lower specificity (74% in OSCC and 93% in OPSCC).[43] Our findings were in agreement with their study, wherein the comparative analysis between IHC and PCR showed sensitivity, specificity, positive predictive value, and negative predictive values of 100%, 68.42%, 50%, and 100% respectively.

Many studies have been done to establish association between OSCC and OPSCC with HPV but very few studies have been done to establish this association in cases with no known risk factors, especially in Indian population, which is the strength of the present study. However, the present study does have few limitations. A prospective study conducted for a longer period of time would give better clarity of data of the patients with a definite personal and habitual history. Further, fresh frozen tissues would be available for HPV confirmation with PCR which gives better results. Thus the present study indicates a strong HPV correlation with OSCC and OPSCC, thereby suggesting it as one of the causative factor for head and neck cancers and as the young population, especially young females, is under threat to develop OSCC and OPSCC without any prior exposure to earlier proven risk factors, prophylactic vaccines against HPV would help in a long-term betterment in these individuals.

Authors’ contribution

PN − Data search, Methodology, Manuscript preparation,

UH − Concept design, Data analysis, Review

SHS − Literature search, Manuscript editing, Proof

SR − Concept design, Review

Acknowledgments

The authors sincerely thank JSSDC&H, JSS AHER, Mysuru for the opportunity to retrieve all data and materials needed for the study, M R Ambedkar Dental College and Hospital, Bangalore, and Credora Life Sciences, Bangalore for their technical support.

Financial support and sponsorship

Nil.

Conflicts of interest

Authors declare no conflicts of interest.



 
  References Top

1.
Dalitsch WW, Vazirani SJ. Oral cancer in women: a study of the increasing incidence. Am J Surg 1959;98:869-74.  Back to cited text no. 1
    
2.
Boyle P, Mac Farlane GJ, Maisonneuve P, Zheng T, Scully C, Tedesco B. Epidemiology of mouth cancer in 1989: a review. J R Soc Med 1990;83:724-30.  Back to cited text no. 2
    
3.
Parkin DM, Pisani P, Feblay J. Estimates of the worldwide incidence of eighteen major cancers in 1985. Int J Cancer 1993;54:594-606.  Back to cited text no. 3
    
4.
Sankaranarayanan R. Oral cancer in India: an epidemiologic and clinical review. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1990;69:325-30.  Back to cited text no. 4
    
5.
Neville BW, Damm DD, Allen CM, Bouquot JE. Oral and Maxillofacial Pathology. 3rd ed. Philadelphia: W.B. Saunders 1995. pp. 295-302.  Back to cited text no. 5
    
6.
Llewellyn CD, Johnson NW, Warnakulasuriya KAAS. Risk factors for squamous cell carcinoma of the oral cavity in young people − a comprehensive literature review. Oral Oncol 2001;37:401-18.  Back to cited text no. 6
    
7.
Llewellyn CD, Linklater K, Bell J, Johnson NW, Warnakulasuriya KAAS. Squamous cell carcinoma of the oral cavity in patients aged 45 years and under: a descriptive analysis of 116 cases diagnosed in the South East of England from 1990 to 1997. Oral Oncol 2003;39:106-14.  Back to cited text no. 7
    
8.
Iamaroon A, Pattanaporn K, Pongsiriwet S et al. Analysis of 587 cases of oral squamous cell carcinoma in northern Thailand with a focus on young people. Int J Oral Maxillofac Surg 2004;33:84-8.  Back to cited text no. 8
    
9.
Shiboski CH, Schmidt BL, Jordan RC. Tongue and tonsil carcinoma: increasing trends in the US population ages20-44 years. Cancer 2005;103:1843-49.  Back to cited text no. 9
    
10.
Mafi N, Kadivar M, Hosseini N, Ahmadi S, Zare-Mirzaie A. Head and neck squamous cell carcinoma in Iranian patients and risk factors in Young adults: a fifteen-year study. Asian Pac J Cancer Prev 2012;13:3373-78.  Back to cited text no. 10
    
11.
Steben M, Duarte-Franco E. Human papillomavirus infection: epidemiology and pathophysiology. Gynecol Oncol 2007;107:S2-5.  Back to cited text no. 11
    
12.
Monk BJ, Tewari KS. The spectrum and clinical sequelae of human papillomavirus infection. Gynecol Oncol 2007;107:S6-13.  Back to cited text no. 12
    
13.
Walboomers JM, Jacobs MV, Manos MM. Human papillomavirus is a necessary cause of invasive cervical cancer worldwide. J Pathol 1999;189:12-9.  Back to cited text no. 13
    
14.
Kreimer AR, Clifford GM, Boyle P, Franceschi S. Human Papillomavirus types in head and neck squamous vell carcinomas worldwide: a systemic review. Cancer Epidemiol Biomarkers Prev 2005;14:467–75.  Back to cited text no. 14
    
15.
Udeabor SE, Rana M, Wegener G, Gellrich NC, Eckardt AM. Squamous cell carcinoma of the oral cavity and the oropharynx in patients less than 40 years of age: a 20-year analysis. Head Neck Oncol 2012;4:28.  Back to cited text no. 15
    
16.
Shafer HL, Rajendran R, Sivapathasundharam B. Shafer’s Textbook of Oral Pathology. 7th ed. Elsevier; 2012. pp. 103-14.  Back to cited text no. 16
    
17.
Llewellyn CD, Johnson NW, Warnakulasuriya KAAS. Factors associated with delay in presentation among younger patients with oral cancer. Oral Surg Oral Med Oral Path 2004;97:707-13.  Back to cited text no. 17
    
18.
Shiboski CH, Schmidt BL, Jordan RC. Tongue and tonsil carcinoma: increasing trends in the US population ages 20-44 years. Cancer 2005;103:1843-49.  Back to cited text no. 18
    
19.
Friedlander PL, Schantz SP, Shaha AR, Yu G, Shah JP. Squamous cell carcinoma of the tongue in young patients: a matched-pair analysis. Head Neck 1998;20:363–8.  Back to cited text no. 19
    
20.
Chiang W, Yen C, Liu S. Squamous cell carcinoma of the oral cavity in Young patients. Chin J Oral Maxillofac Surg 2005;16:8-16.  Back to cited text no. 20
    
21.
Mehrotra R, Singh MK, Pandya S, Singh M. The use of an oral brush biopsy without computer − assisted anaylsis in the oral lesions: a study of 94 patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:246-53.  Back to cited text no. 21
    
22.
Jaber MA. Oral epithelial dysplasia in non-users of tobacco and alcohol: an analysis of clinicopathologic characteristics and treatment outcome. J Oral Sci 2010;52: 13−21.  Back to cited text no. 22
    
23.
Myers JN, Elkins T, Roberts D, Byers RM. Squamous cell carcinoma of the tongue in young adults: increasing incidence and factors that predict treatment outcomes. Otolaryngol Head Neck Surg 2000;122:44-51.  Back to cited text no. 23
    
24.
Burzynski NJ, Flynn MB, Faller NM, Ragsdale TL. Squamous cell carcinoma of the upper aerodigestive tract in patients 40 years of age and younger. Oral Surg Oral Med Oral Pathol 1992;74:404–8.  Back to cited text no. 24
    
25.
Giervasio OL, Dutra RA, Tartaglia SM, Vasconcellos WA, Barbosa AA, Agular MC. Oral squamous cell carcinoma: a retrospective study of 740 cases in a Brazilian population. Braz Dent J 2001;12:57-61.  Back to cited text no. 25
    
26.
Hibbert J, Marks NJ, Winter PJ, Shaheen OH. Prognostic factors in oral carcinoma and their relation to clinical staging. Clin Otolaryngol 1983;8:197-203.  Back to cited text no. 26
    
27.
Ahmed F, Islam KM. Site predilection of oral cancer and its correlation with chewing and smoking habit—a study of 103 cases. Bangladesh Med Res Counc Bull 1990;16:17-25.  Back to cited text no. 27
    
28.
Chattipadhyay A. Epidemiologic study of oral cancer in eastern India. Indian J Dermatol 1989;34:59-65.  Back to cited text no. 28
    
29.
Chen YK, Huang HC, Lin LM, Lin CC. Primary oral squamous cell carcinoma: an analysis of 703 cases in southern Taiwan. Oral Oncol 1999;35:173-9.  Back to cited text no. 29
    
30.
Reichart PA. Oral cancer and precancer related to betel and miang chewing in Thailand: a review. J Oral Pathol Med 1995;24:241-3.  Back to cited text no. 30
    
31.
Kuriakose M, Sankaranarayanan R, Nair MK. Comparison of oral squamous cell carcinoma in younger and older patients in India. Eur J Cancer Oral Oncol 1992;28B:113-20.  Back to cited text no. 31
    
32.
Breslow NE, Storer BE. General relative risk function for case-control studies. Am J Epidemiol 1985;122:149-62.  Back to cited text no. 32
    
33.
França DC, Monti LM, de Castro AL, Soubhia AM, Volpato LE, de Aguiar SM et al. Unusual presentation of oral squamous cell carcinoma in a young woman. Sultan Qaboos Univ Med J. 2012;12(2):228-31.  Back to cited text no. 33
    
34.
Hirayama T. An epidemiological study of oral and pharyngeal cancer in Central and South East Asia. Bull World Health Organ 1966;34:41-69.  Back to cited text no. 34
    
35.
Thomas S, Wilson A. A quantitative evaluation of the aetiological role of betel-quid in oral carcinogenesis. Eur J Cancer 1993;29B:265-71.  Back to cited text no. 35
    
36.
Barra S, Franceschi S, Negri E, Talamini R, la Veccia C. Type of alcoholic beverage and cancer of the oral cavity, pharynx and oesophagus in an Italian area with high wine consumption. Int J Cancer 1990;46:1017-20.  Back to cited text no. 36
    
37.
Breslow NE, Storer BE. General relative risk function for case-control studies. Am J Epidemiol 1985;122:149-62.  Back to cited text no. 37
    
38.
Prime SS, Mac Donald DG, Rennei JS. The effect of iron deficiency on experimental oral carcinogenesis in the rat. Br J Cancer 1983;47:189-92.  Back to cited text no. 38
    
39.
Monkman G, Orwoll G, Ivins JC. Trauma and oncogenesis. Mayo Clin Proc 1974;49:157-63.  Back to cited text no. 39
    
40.
Rodriguez T, Altieri A, Chatenoud L et al. Risk factors for oral and pharyngeal cancer in young adults. Oral Oncol 2004;40:207-13.  Back to cited text no. 40
    
41.
Snow AN, Laudadio J. Human papillomavirus detection in head and neck squamous cell carcinomas. Adv Anatomic Pathol 2010;17:394-403.  Back to cited text no. 41
    
42.
Robinson M, Sloan P, Shaw R. Refining the diagnosis of oropharyngeal squamous cell carcinoma using human papillomavirus testing. Oral Oncol 2010;46:492-6.  Back to cited text no. 42
    
43.
Pannone G, Rodolico V, Santoro A et al. Evaluation of a combined triple method to detect causative HPV in oral and oropharyngeal squamous cell carcinomas: p16 Immunohistochemistry, Consensus PCR HPV-DNA, and in situ hybridization. Infect Agents Cancer 2012;7:4.  Back to cited text no. 43
    
44.
Kaminagakura E, Villa LL, Andreoli MA et al. High-risk human papillomavirus in oral squamous cell carcinoma of young patients. Int J Cancer 2012;130:1726-32.  Back to cited text no. 44
    
45.
El-Mofty SK, Patil S. Human papillomavirus (HPV)- related oropharyngeal non keratinizing squamous cell carcinoma: characterisation of a distinct phenotype. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;101:339-45.  Back to cited text no. 45
    
46.
Dong Y, Wang J, Dong F, Wang X, Zhang Y. The correlations between alteration of p16 gene and clinicopathological factors and prognosis in squamous cell carcinomas of the buccal mucosa. J Oral Pathol Med 2012;41:463-69.  Back to cited text no. 46
    
47.
Weinberger PM. Prognostic significance of p16 protein levels in oropharyngeal squamous cell cancer. Clinl Cancer Res 2004;10:5684-91.  Back to cited text no. 47
    
48.
Shillitoe EJ. The role of viruses in squamous cell carcinoma of the oropharyngeal mucosa. Oral Oncol 2008;33:111-7.  Back to cited text no. 48
    
49.
Mulder FJ, Pierssens DDCG, Baijens LWJ, Kremer B, Speel EM. Evidence for different molecular parameters in head and neck squamous cell carcinoma of nonsmokers and nondrinkers: Systematic review and meta-analysis on HPV, p16, and TP53. Head Neck 2021;43:303-22.  Back to cited text no. 49
    
50.
Hashmi AA, Younus N, Naz S et al. p16 immunohistochemical expression in head and neck squamous cell carcinoma: association with prognostic parameters. Cureus. 2020;12:e8601.  Back to cited text no. 50
    
51.
Lechner M, Liu J, Masterson L et al. HPV-associated oropharyngeal cancer: epidemiology, molecular biology and clinical management. Nat Rev Clin Oncol 2022;19:306-27.  Back to cited text no. 51
    
52.
Yang LQ, Xiao X, Li CX et al. Human papillomavirus genotypes and p16 expression in oral leukoplakia and squamous cell carcinoma. Int J Clin Exp Pathol. 2019;12:1022-28.  Back to cited text no. 52
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Material and Methods
Results
Discussion
References
Article Tables

 Article Access Statistics
    Viewed120    
    Printed8    
    Emailed0    
    PDF Downloaded23    
    Comments [Add]    

Recommend this journal