developing cancer. The International Agency for Research on Cancer (IARC) has designated 12 (HPV) types as high risk according to their potential to induce malignant change with several other types as probably or possibly carcinogenic (Taberna et al., 2017). In the U.S., high-risk HPV types cause 3% of all cancers among women and 2% of all cancers among men (National Cancer Institute, 2019). The most aggressive forms of carcinogenic HPV are linked to cancers of the cervix, anus, vulva, vagina, penis, and throat (National Cancer Institute, 2019). HPV types 16 and 18 are responsible for the majority of HPV-related cancers, including cervical cancer (National Cancer Institute, 2022; CDC, 2017a). Non-carcinogenic HPV types are considered “low risk.” Although these types do not cause cancer, they can cause warts on or around the genitals and anus; HPV types 6 and 11 cause 90% of all genital warts (WebMD, 2022). HPV types 16 and 18 contribute to 70% of the onset of invasive cervical cases globally (Ahmed et al., 2017). In contrast, oropharyngeal cancers are most often associated with HPV type 16, with a very small proportion of cases caused by types such as 18, 31, 33, 35, 52, and 58 (Rehan, 2017). Table 1 presents HPV-related diseases and causative HPV types.
reports that more than 200 HPV types have been identified and numbered (CDC, 2017a; Syrjanen, 2018). A discussion of viral identification and typing is beyond the intent of this course. The viruses are categorized according to the types of cells they infect and their ability to bring about cellular changes (van Heerden WFP, et al., 2017). There are two kinds (genera) of HPV: the genus alpha, which exhibits a mucosal tropism, and genus beta, which infects cutaneous cells (van Heerden, WFP, et al., 2017). Cutaneous HPV types are typically found in skin lesions such as benign skin warts and non-melanoma skin cancers. Most mucosal HPV types belong to the alpha genus some of which are the high-risk types of HPV and are associated with cervical cancer and other HPV-related cancers, such as oral cancers, affecting mucosal membranes (Syrjanen, 2018). HPV types are also classified according to their cancer- causing ability (Taberna, et al., 2017). Non-cancer- causing HPV types are described as noncarcinogenic (or non-oncogenic ), while those types causing cancer are described as carcinogenic (or oncogenic ). Researchers have also ascribed levels of risk to carcinogenic HPV types. Carcinogenic HPV types are considered high risk because their presence places an individual at higher risk for Table 1: HPV-Related Disease and Associated HPV Type Disease HPV Type Common warts
Noncarcinogenic: 1, 2, 3, 5, 7, 22, 27, 29, 57
Plantar warts
Noncarcinogenic: 1, 2, 4, 57,63 Noncarcinogenic: 3, 10, 8, 28 Noncarcinogenic: 6, 11, 42, 44
Flat warts
Anogenital warts Genital cancers
• Carcinogenic: 16, 18, 31, 45 • Very likely carcinogenic: 33, 35, 39, 51, 52, 56, 58, 59 • Probably carcinogenic: 26, 53, 66, 68, 73, 82 • Possibly carcinogenic: 6, 11, 40, 42, 43, 44, 54, 61, 70, 72, 81
Oral papillomas
• Carcinogenic: 16 • Possibly carcinogenic: 6, 11 • Noncarcinogenic: 7, 32
Oropharyngeal cancer Laryngeal papillomatosis
Carcinogenic: 16
Possibly carcinogenic: 6, 11
Sinus papillomas Possibly carcinogenic: 57 Note. Adapted from Aboud Ahmad M. and Nigam Pramrod K. Wart. StatPearls Publishing, LLC. August 8, 2022. https://www.ncbi. nlm.nih.gov>books>NBK431047; Baardsen Erika M. and Rosa Marlin. Cervix. Premalignant/preinvasive lesions-H&E. HPV. Pathology Outlines. Last update October 20, 2022. https://pathologyoutlines.com>topic>cervichpv; Sun Caihong, Gu Heng, Zhang Caiping, Du Suping, Xu Shengjing and Jiang Juan. Indian Journal of Dematology . 2017. September-October; 62(5):549. https://www.ncbi. nlm.gov>articles>PMC5618861; and Stanford. Human Papillomavirus. Who is affected by HPV infection. No date. https://stanford. edu>papova>HPV ORAL HPV
types related to their ability to cause cancer in the head and neck area; low-risk types of HPV can cause warts in the oral cavity or pharynx (National Cancer Institute, 2022). In the oropharynx the (HPV) has a high selectivity for the areas of the tonsillar tissues and crypts as approximately 48% of oropharyngeal carcinomas are HPV-positive while carcinomas of the oral cavity have an approximate range of 24-38% of HPV found within these lesions (Rodriguez & Stuardo, 2019). Most noncancerous HPV lesions in the oral cavity are without symptoms and are cleared within one-two years yet some HPV infections persist (CDC, 2018a).
HPV is most widely identified with its role in cervical cancer, but the virus has been identified as a principal cause of the increasing incidence rates of oropharyngeal squamous cell carcinoma (OPSCC) (Taberna, 2017). The same types of HPV that infect the genital areas can infect the oral cavity and pharynx. Oral HPV infection occurs when the virus infects the oropharyngeal area, including the tongue, tonsils, and buccal and lingual mucosa (American Dental Association, 2022). Although the oral cavity and oropharynx are proximate structures, they are considered as two distinct anatomical and functional areas. As with other HPV types, some types of oral HPV are termed low-risk or high-risk Types, prevalence, and incidence Studies suggest that oral HPV is present in approximately 7% of people in the U.S. Of these, only 1% are infected with HPV type 16, the type clearly linked to oral cancer (The
Cleveland Clinic, 2022). Common types of noncarcinogenic oral lesions associated with HPV include the following: squamous papilloma, verruca vulgaris, focal epithelial
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