Research has shown that a particular kind of s*x has the capacity of increasing the vulnerability of one developing getting cancer.
New research has found that practising oral sex can dramatically increase the risk of developing throat cancer by as much as 22 times.
A study found that people carrying the virus HPV (human papillomavirus)-16 were twenty two times more likely to suffer from a potentially lethal tumour.
It is thought that performing oral s*x is the most likely way the HPV virus - usually associated with cervical cancer - is spread to the mouth
Michael Douglas, star of Basic Instinct and Fatal Attraction, claimed HPV was the cause of his almost-fatal cancer diagnosis in August 2010.
He beat the odds by recovering from a stage four tumour, which is often terminal.
But the study, published in JAMA Oncology, is the first to show conclusively HPV-16's presence in the mouth leads to the development of oropharyngeal cancer, the type that affected Douglas.
HPV-16 is a well-known cause of 'oropharyngeal' tumours which affect the middle part of the throat including the soft palate, the base of the tongue and the tonsils.
The new finding was based on a study of almost 97,000 people who had traces HPV-16 in their mouth. They were cancer free at the start of the project and were followed for an average of four years, during which time a total of 132 cases of head and neck cancer were identified.
This was compared with 396 healthy subjects who acted as controls, with mouthwash samples analysed for the presence of several types of oral HPVs in both groups.
This showed people with HPV-16 in their mouthwash were 22 times more likely to develop oropharyngeal cancer than were those with no detectable trace of the virus HPV-16.
Dr Ilir Agalliu, of the Albert Einstein College of Medicine, New York, said: "This study shows using easily collected oral mouthwash samples may help in predicting people's risk for developing head and neck cancers."
People traditionally view throat cancer as a disease that affects smokers and heavy drinkers in later life but over recent years, as cases have been rising, its been linked with the common HPV.
Spread by skin-to-skin contact, not just by sex, HPV affects almost everyone at some stage in their life.
In most of us, our immune system fights it off and it does not do any harm. But on rare occasions, the virus takes hold, leading to a chain of events that ends in cancer of the cervix, penis, anus, vagina or mouth.
Around fifteen strains can cause cervical cancer, and HPV-16 is the most common. It is one of the fastest rising cancers in the UK, now affecting around 5,000 people each year.
One of the largest studies of its kind found people who had more than six oral s*x partners, or more than 26 vaginal s*x partners, in their lifetime had an increased risk of oral cancer.