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Oral Sex and Oral Cancer
With recent reports in the press linking oral cancer and oral sex, Dr Vinod K Joshi gives the low-down on everything you ever wanted to know about oral sex and mouth cancer, but were too afraid to ask.
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High consumptions of alcohol and cigarettes are estimated to cause about 75 percent of all cases of oral cancer. The combination of tobacco smoke and alcohol are thought to produce high levels of cancer causing agents. These cases are seen typically in the older patient.
But that still leaves a small but significant group of people with oral cancer whose disease cannot be blamed on decades of smoking and drinking, because they're too young. In the past decade, Scotland has seen an almost 50 percent increase in oral cancer among under-45s, and in the last 40 years a fourfold increase in younger patients suffering from it. Now it is thought that there may be an uncomfortable explanation to account for this.
The human papilloma virus (HPV) is an extremely common sexually transmitted infection, and has long been known to cause cervical cancers. It had long been suspected, that HPV could cause oral cancers. Several studies had suggested it also played a role in other cancers, including oral and anal cancers.
HPV is one of the most common virus groups in the world to affect the skin and mucosal areas of the body. Over 80 types of HPV have been identified. HPV family of viruses comprises ‘low risk’ viruses linked to benign infections such as warts and papillomas and ‘high-oncogenic-risk’ viruses 16 and 18 linked to oral and cervical cancer. Genital HPV infections are common. Genital warts are known technically as condylomata acuminatum and are generally associated with two HPV types, numbers 6 and 11 and can be sexually transmitted. The warts tend to be infective, but can be treated. There is no reliably effective treatment though it ‘looks’ nicer if warts are removed.
The problem is that HPV is often clinically undetectable. At any one time, around a third of 25-year-old women in the US are infected. It is thought that only 10 percent of infections involve cancer-causing strains, and that 95 percent of women will get rid of the infection within a year. Most HPV infections of this type are very common, harmless, non cancerous and easily treatable.
The higher risk HPV-16 viruses are also spread by sexual activity. Once in the body, the virus persists and moves to other mucosal sites via self-inoculation from the genitalia or oro-genital contact between sexual partners. Mothers harbouring the virus can transmit the virus to their babies during birth. HPV-16 virus is detected in the buccal cells of just under 50 per cent of their asymptomatic pre-pubertal children. So avoiding initial exposure to the virus is impossible.
HPV is the most prevalent STD in the US at present. It is estimated that well over one third of youngsters are infected. Men are at greater risk than women of developing oral cancer. This is thought to be related to significant differences in male sexual behaviour. Men with oral cancer self-reported a lower age for their first sexual intercourse, an increased number of sexual partners, and a history of genital warts. In a high proportion of women with oral cancer, the same HPV type was also found in their cervical smears.
According to Dr. Buck, gynaecologist at Watkins Health Centre, ‘Fifty to 60 percent of US college-aged women have HPV, but only 10 percent have lesions.’ Condom use, and sensible behaviour, is considered to be protective against HPV infection.
Recently in a Johns Hopkins study, published in the Journal of the National Cancer Institute, researchers working for the International Agency for Research on Cancer in Lyon, France, compared 1670 patients who had oral cancer with 1732 healthy volunteers. The participants lived in Europe, Canada, Australia, Cuba and Sudan. The researchers took tissue biopsies to see if the HPV virus was present. HPV16, the strain seen most commonly in cervical cancer, was found in most of the oral cancers too.
It was more common amongst people who reported having more than one sexual partner or who practiced oral sex, than in cancer patients who smoked or chewed tobacco. The people with oral cancers containing the HPV16 strain were three times as likely to report having had oral sex as those whose tumour did not contain HPV16. Patients with mouth cancer were also three times as likely to have antibodies against HPV compared to the healthy controls. For cancers of the back of the mouth, the link was even stronger. The results prove the connection between HPV and oral cancer beyond any reasonable doubt.
It is thought that the transmission of the virus is facilitated by oral sex. However, the researchers are not recommending any changes in behaviour as the risk, thankfully, is tiny! Only around 1 in 10,000 people develop mouth cancers each year, and most cases are probably caused by two other popular recreational pursuits: smoking and drinking. Researchers publishing recent findings worry about media sensationalism and caution against overdoing HPV scare tactics as millions of people infected with HPV suffer no symptoms as a result. While HPV is the main cause of cervical cancer, and a cause of some oral cancer, most people with the virus do not get cancer of any type. But people are concerned as evidenced by variants of words, ‘oral sex mouth cancer’ and ‘human papilloma virus’ being very popular among search strings used to access the Mouth Cancer Foundation website.
Several research groups are developing vaccines against HPV, intended to reduce the deaths worldwide each year due to cervical cancer. It is thought these vaccines would prevent oral infections as well as genital infections. Many scientists also think that giving antiviral drugs to people with oral cancers caused by the virus could improve their chances of recovery.
The only sensible bottom-line advice I could get from local experts was, ‘Oh, Behave!’ ‘Watch your Mouth!’ and if you can’t, ‘Wear (flavoured?) Condoms!’
About the author
Dr Dr Vinod K Joshi BDS DRDRCS FDSRCPS is Consultant in Restorative Dentistry, Restorative Dentistry Oncology Clinic, St Luke's Hospital, Bradford and Pinderfields Hospital, Wakefield.
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