S. Noori, A. Monabati, A.A. Ghaderi 5 Zur Hausen H. Papillomavirus infections- -a major cause of human cancers. Biochim Biophys Acta. 1996;1288:55-78. PubMed PMID: 8876633. 6 Vousden K. Interactions of human papillo- mavirus transforming proteins with the prod- ucts of tumor suppressor genes. FASEB J. 1993;7:872-9. 7 Huibregtse JM, Beaudenon SL. Mechanism of HPV E6 proteins in cellular transforma- tion. Semin Cancer Biol. 1996;7:317-26. doi: 10.1006/scbi.1996.0041. PubMed PMID: 9284524. 8 Zur Hausen H. Papillomavirus and p53. Nature. 1998;393:217. PubMed PMID: 9607756. 9 Miller OJ, Therman E. Human chromo- somes. 4th ed. New York: Springer-Verlag; 2001. 10 Yagi N, Satonaka K, Horio M, Shi- mogaki H, Tokuda Y, Maeda S. The role of DNase and EDTA on DNA degrada- tion in formaldehyde fixed tissues. Bio- tech Histochem. 1996;71:123-9. doi: 10.3109/10520299609117148. PubMed PMID: 8724437. 11 Noguchi M, Furuya S, Takeuchi T, Hirohashi S. Modified formalin and methanol fixation methods for molecular biological and morpho- logical analyses. Pathol Int. 1997;47:685-91. doi: 10.1111/j.1440-1827.1997.tb04442.x. PubMed PMID: 9361102. 12 Díaz-Cano SJ, Brady SP. DNA extraction from formalin-fixed, paraffin-embedded tis- sues: protein digestion as a limiting step for retrieval of high-quality DNA. Diagn Mol Pathol. 1997;6:342-6. PubMed PMID: 9559294. 13 de Villiers EM, Lavergne D, Chang F, Syrjänen K, Tosi P, Cintorino M, et al. An interlaboratory study to determine the presence of human papillomavirus DNA in esophageal carcinoma from China. Int J Cancer. 1999;81:225-8. doi: 10.1002/ (SICI)1097-0215(19990412)81:2<225::AID- IJC10>3.3.CO;2-S. PubMed PMID: 10188723. 14 Li T, Lu ZM, Chen KN, Guo M, Xing HP, Mei Q, et al. Human papillomavirus type 16 is an important infectious factor in the high inci- dence of esophageal cancer in Anyang area of China. Carcinogenesis. 2001;22:929- 34. doi: 10.1093/carcin/22.6.929. PubMed PMID: 11375901. 15 Si HX, Tsao SW, Poon CS, Wong YC, Cheung AL. Physical status of HPV-16 in esophageal squamous cell carcinoma. J Clin Virol. 2005;32:19-23. PubMed PMID: 132 15572001. 16 Shen Z, Cen S, Shen J, Cai W, Xu J, Teng Z, et al. Study of immortalization and malignant transformation of human embryonic esopha- geal epithelial cells induced by HPV18 E6E7. J Cancer Res Clin Oncol. 2000;126:589-94. doi: 10.1007/PL00008469. PubMed PMID: 11043396. 17 Morgan RJ, Perry AC, Newcomb PV, Hard- wick RH, Alderson D. Human papillomavirus and oesophageal squamous cell carcinoma in the UK. Eur J Surg Oncol. 1997;23:513- 7. doi: 10.1016/S0748-7983(97)92981-4. PubMed PMID: 9484921. 18 Saegusa M, Hashimura M, Takano Y, Ohbu M, Okayasu I. Absence of human papilloma- virus genomic sequences detected by the polymerase chain reaction in oesophageal and gastric carcinomas in Japan. Mol Pathol. 1997;50:101-4. doi: 10.1136/mp.50.2.101. PubMed PMID: 9231159; PubMed Central PMCID: PMC379592. 19 Farhadi M, Tahmasebi Z, Merat S, Kaman- gar F, Nasrollahzadeh D, Malekzadeh R. Human papillomavirus in squamous cell car- cinoma of esophagus in a high-risk popula- tion. World J Gastroenterol. 2005;11:1200-3. PubMed PMID: 15754405. 20 Sadjadi AR, Marjani H, Semnani Sh, Nasseri- Moghaddam S. Esophageal cancer in Iran: a review. Middle East J Cancer. 2010;1:5-14. 21 Shuyama K, Castillo A, Aquayo F, Sun Q, Khan N, Koriyama C, et al. Human papilloma- virus in high- and low-risk areas of oesopha- geal squamous cell carcinoma in China. Br J Cancer. 2007;96:1554-9. doi: 10.1038/ sj.bjc.6603765. PubMed PMID: 17453003; PubMed Central PMCID: PMC2359949. 22 McGhee JD, von Hipple PH. Formaldehyde as a probe of DNA structure. 3. Equilibrium denaturation of DNA and synthetic polynu- cleotides. Biochemistry. 1977;16:3267-76. PubMed PMID: 560859. 23 Srinivasan M, Sedmak D, Jewell S. Effect of fixatives and tissue processing on the content and integrity of nucleic acids. Am J Pathol. 2002;161:1961-71. doi: 10.1016/ S0002-9440(10)64472-0. PubMed PMID: 12466110; PubMed Central PMCID: PMC1850907. 24 Nitta Y, Tanaka H, Masuda Y, Hoshi M. The quality of DNA recovered from the archival tissues of atomic bomb survivors is good enough for the single nucleotide polymor- phism analysis in spite of the decade-long preservation in formalin. J Radiat Res. 2002;43:65-75. doi: 10.1269/jrr.43.65. PubMed PMID: 12056331. Iran J Med Sci June 2012; Vol 37 No 2