Shockingly, recent surveys suggest
that fifty percent of sexually active adults
in the United States have been infected with two or more
of seven genital HPV strains.
Unfortunately for sexually active
adults, HPV is readily transmissible. HPV transmission does not necessarily require penetrative acts and thereby can be
transmitted via any form of genital
contact including vaginal, anal, and oral sex.
Beyond transmission via genital
contact, HPV can target almost any basal
epithelial cell on your skin. In this way, HPV may be transmitted through a
number of less obvious routes. Since HPV can persist in a wide range of
temperatures and is resistant to desiccation, nonsexual transmission via
fomites can also occur, such as by prolonged exposure to a contaminated object
(ie: dirty sheets or clothes). This means HPV can be transmitted
through seemingly harmless acts, such as open-mouthed kissing and even shared
drinks.
During HPV transmission, HPV’s L1
protein binds to heparan sulfate proteoglycans (HSPGs) found in the lamina
densa of the basal lamina (a part of the basement membrane) of the epidermis.
Although not all HPV strains are
“dangerous”, at least three of the seven genital strains of HPV have been found
to be oncogenic. In the case of cervical cancer, oncogenic HPV substrains 16,
18, and 33 have been found in 99% of cervical cancers worldwide. To make the
connection to oral health, genomic DNA of oncogenic HPV (subtypes 16, 18, and
33) has been detected in approximately 26% of all head and neck squamous-cell
carcinomas (HNSCC). Although the means by which oncogenic
HPV subtypes become associated with the stratified squamous epithelium of the
head and neck region is not well understood, emerging research suggests sexual behaviors may influence the
transition from the genital region to the head and neck region, due to the
efficacy of HPV transmission.
As a subclass of head and neck
squamous-cell carcinomas, oral and oropharyngeal cancers also have a frequent
association with HPV 16 (one of the oncogenic strains). One case study suggests
that a high lifetime number of oral-sex or vaginal-sex partners, engagement in
casual sex, early age at first intercourse, and infrequent use of condoms are
all associated with HPV-16–positive oropharyngeal cancer. Another case study
found that the odds of oral HPV infection increased with the number of oral sex
partners or open-mouthed kissing partners, indicating that oral HPV infection is sexually acquired and is
transmitted by behaviors as common as open-mouthed kissing.
Since dentists usually only screen
for oral cancer in at-risk patients (usually frequent smokers), informing your
dentist about your sexual habits will enable them to perform more thorough oral
/ oropharyngeal cancer screenings, thus possibly saving your life!
Sources:
1) Workowski K.
2010. Sexually Transmitted Diseases Treatment Guidelines – 2010. Morbidity and
Mortality Weekly Report Recommendations and Reports.
2) Burd E. 2003.
Human Papillomavirus and cervical cancer. Clinical Microbiology Reviews. 16(1):
1–17.
3) Schiller J, Day
P, Kines C. 2010. Understanding of the mechanism of HPV infection. Gynecologic Oncology. 118(1):
S12-S17.
4) D’Souza
G, Agrawal Y, Halpern J, Bodison S, Gillison M. 2009. Oral sexual behaviors
associated with prevalent oral human papillomavirus infection. Journal of
Infectious Diseases. 199(9): 1263-1269.
5) D’Souza G, Kreimer
A, Viscidi R, Pawlita M, Fakhry C, Koch W, Westra W, Gillison M. 2007. Case–control
study of human papillomavirus and oropharyngeal cancer. New England Journal of
Medicine. 356(19): 1944-1956.
