Dear Dr G,

I wish to put Dr. G on the spot this week regarding the safety of oral sex.

My husband and I have been married for six months after knowing each other for two years.

As devoted Christians, we abstained from sexual activities before marriage.

My husband is keen on engaging in oral sex, but I’m hesitant due to reports linking it to oral cancer.

I’m concerned after reading that oral sex can transmit HPV, a virus associated with cancer.

Firstly, what exactly is HPV? And how common is this infection?

I often associate HPV with cervical cancer, how can HPV cause oral cancer?

How common is oral cancer in general? And how can this be prevented?

Finally, I have heard about the HPV vaccine, do you think we should both get it for cancer prevention?

Yours truly,

Fearful Florence

Oral sex is generally considered an enjoyable and healthy part of sexual intimacy, often performed as foreplay to incite arousal prior to penetrative intercourse.

Like any form of sexual act involving the exchange of bodily fluid, oral sex can pose a risk of contracting sexually transmitted infections. However, scientific evidence generally agrees that the risk of transmission disease through oral sex is significantly lower than vaginal or anal sex. The pathogens recognised to be transmissible through oral-genital contacts are chlamydia, gonorrhea, herpes, hepatitis, HIV and HPV.

Human Papillomavirus (HPV) has more than one hundred subtypes and is an infection postulated to affect nearly all sexually active individuals at some point in their lives, making it the most common form of sexually transmitted infection.

The initiation of sexual contacts, including oral and anal sex can potentially induce the transmission of the virus. Although the virus is contagious, nearly 90% of the infections remain asymptomatic and resolve spontaneously within two years. However, persistent infections can result in warts and precancerous lesions. The infection increases the risk of genital warts and cancers of penis, vulva, vagina, anus, mouth and throat, especially in at-risk individuals. The most devastating and common HPV-induced cancer is actually cervical cancer, followed by oral and anal cancers that also affect men.

The reported links of oral sex and HPV induced oral cancers are generally based on two studies. In 2005, Malmo University highlighted that 36% of oral cancer patients had HPV, compared to only 1 percent of healthy individuals.

Another study published in The New England Journal of Medicine suggests a correlation between oral sex and throat cancer, concluding that individuals with one to five oral sex partners in their lifetime had approximately double the risk of throat cancer, with the risk increasing by 250% with more than five partners.

It is clear that oral sex itself does not directly result in cancer. Generally, 90% of HPV infections are believed to be cleared by the body’s immunity within two years.

Early onset of sexual intercourse, multiple sexual partners, and poor immunity are the risk factors associated with persistent and progression of HPV infections. Smoking and high alcohol consumption also increase the risks of viral transition to malignancy. Although many reports highlighted the protections of condoms against the transmission of HPV in vaginal and anal intercourse, the protection of such barrier technique in oral sex is less commonly practised and the degree of protection is not commonly reported.

Nearly all cervical cancers are caused by HPV. An estimated 569,000 new cases of cervical cancer were reported in 2018, with more than 310,000 deaths recorded from this cancer, especially in developing countries. On the other hand, 40% of oropharyngeal cancers are caused by HPV. The prevalence of oropharyngeal cancer is significantly lower when reported globally per annum. Men have a five times higher risk of contracting oropharyngeal cancers compared to women.

Contrary to being a low-income nation cancer, oropharyngeal cancer more commonly affects developed countries such as the USA, Europe, and Australia. As the trend of cervical cancers declines in these countries, the prevalence of oropharyngeal cancers has gradually increased over the decades.

The advent of the HPV vaccine may potentially be a game-changer for the prevention of HPV-linked cancer through oral sex. The new generation of women protected by such vaccination is likely to witness a decline in oral cancers in both men and women through herd immunity. It is also increasingly recognised as important to protect boys through such valuable scientific advancements. Although evidence is lacking for the protection offered by HPV vaccines for non-virgins (oral or penetrative), the vaccination is still believed to offer some protection.