More young people are being diagnosed with mouth cancer - with NHS chiefs blaming oral sex for the sharp rise.
Figures show more people are suffering from mouth and throat cancers with the number continuing to grow.
Mouth cancer is largely preventable and often caused by smoking and alcohol. But a sexually transmitted infection called the human papillomavirus (HPV) is also increasingly to blame.
A small number of high-risk strains of HPV can cause cancer in the mouth, cervix, vulva, vagina, anus, penis and tonsils.
Actor Michael Douglas revealed in 2013 that his cancer was caused by HPV through performing oral sex.
Now NHS England is helping dentists spot the signs and advise patients on how to cut the risk.
Dr Yvonne Dailey, a consultant in dental public health, said: "Oral cancer is a growing health care concern for the NHS yet more than 90 per cent of oral cancers are preventable.
"If oral cancer is diagnosed early survival rates are good; delay is costing lives. It is vital that dentists, dental teams and their patients understand the importance of their role in relation to prevention, early detection and referral."
What are the symptoms of oral cancer?
Symptoms include red or red and white patches in the mouth, ulcers or swellings that do not heal after three weeks, pain while swallowing and a feeling something is stuck in the throat.
How common are HPV and oral cancer?
Around 11,400 mouth, tongue and other rarer head or neck cancers were diagnosed in 2014.
Cancer Research UK figures suggest around 1 in 75 men and 1 in 150 women will be diagnosed in their lifetime, but rates are expected to rise by a third by 2035.
HPV infections are a lot more common, with most people reportedly exposed to them by the age of 25.
But most HPV strains have no cancer link and very few people infected develop the disease.
The infection is usually cleared naturally by the body within two years.
Very few people infected with HPV develop cancer, with the infection naturally cleared by the body.
How can you prevent HPV and mouth cancer?
Giving up smoking, drinking less and better diet are all believed to cut the risk.
Girls aged 12 and 13 are vaccinated against HPV already to protect them from vulval and vaginal cancers.
NHS advice is that this will "probably" protect them from anal and oral cancer too, with the impact currently being reviewed.
Health chiefs also urge people to use condoms or dams during oral sex, and check for symptoms.
