• Most people catch it and their body clears it eventually
• In some cases it persists and is linked to several types of cancer, such as of the cervix, penis, anus and throat
• A vaccine, Gardasil, can protect against four HPV strains, two of which are linked to cancers and two to warts
• The vaccine is state funded in NZ for girls
• Parents who want their boys vaccinated have to pay about $450
Throat-cancer patient Grant Munro paid for his son to be vaccinated against the sexually-transmitted HPV virus because the Government has refused.
A 58-year-old scientific expert on viruses, he is backing a campaign by doctors calling for the extension of state funding of the controversial HPV vaccine to boys. Dr Munro, whose cancer was linked to HPV infection, says it is a form of discrimination against males that the Government will only pay for girls to have the vaccine.
State medicines agency Pharmac said it had decided not to fund the Gardasil vaccine for boys at present, but it is an option for the future. Its advisory committee assigned a low priority to funding it for all males aged 11-19 and high priority for males 9-26 "who self-identify as having sex with other males".
In Australia, the vaccine is government-funded for boys and girls. Gardasil can protect against four strains of HPV - human papilloma virus - that can cause pre-cancerous lesions in the genital tract and mouth, and genital warts. It has been offered to New Zealand girls partly to help reduce cervical cancer.
Rates of throat-related cancers have risen sharply since the 1980s and HPV, from oral sex, is thought to be the cause. The actor Michael Douglas was treated for tongue cancer caused by HPV and has spoken of the link between HPV and performing oral sex.
After Dr Munro was treated for a tonsil tumour that contained evidence of HPV, he paid $450 for his 14-year-old son to receive the three injections of vaccine.
In 2013, Dr Munro had delayed seeking medical help for throat problems he put down to hayfever - "a sort of sore throat, sometimes a little difficulty swallowing, sometimes a little blood in the saliva, snoring. I now also remember having ferocious night sweats."
His GP sent him to a throat surgeon who, within days, removed his left tonsil. Chemotherapy and radiotherapy followed. He thought he was in remission from cancer, until last week when a PET scan showed up a "highly suspicious" lymph node in his neck. Now he has been referred to a cancer specialist to discuss his options.
Dr Munro is a patient-representative of the HPV project, a group of specialists and patients, which promotes vaccination against the virus, and he will speak at its Auckland University event this week.
Surgeons report seeing many more cases of cancer of the tonsils, the base of the tongue, the back of the throat and the soft palate - together called oropharyngeal cancers.
From around 1990 to 2010, the per-capita rate of these cancers in New Zealand men more than doubled, to more than 4 per 100,000. The female rate rose significantly too, but is much lower than for men, at around 1 per 100,000 each year.
"Men are more exposed to the virus," said Auckland ear, nose and throat surgeon Dr John Chaplin, "because the route of exposure is understood to be oral sex and that the concentration of virus in the female genital tract is much higher than in the male tract".
"Previously all these tumours related to smoking and alcohol exposure and the rates of those are going down."
Patients with HPV-linked throat tumours have better survival prospects, at around a 90 per cent chance of still being alive without any progression of the disease two years after diagnosis, but the side effects of treatment can be severe.
Waikato ENT doctors Theresa Muwanga-Magoye and Julian White have said that in the US, the male oropharyngeal cancer rate exceeds the cervical cancer rate, and that reasons for this may include HPV vaccination of girls, cervical screening of women, smoking, alcohol and other lifestyle factors.
Dr White said that because the rate of male oropharyngeal cancer in New Zealand had risen significantly closer to the cervical cancer rate, "it should be seen as just as important as cervical cancer when discussing HPV-related cancers and their prevention and treatment".
Gayle Dickson, of the Gardasil Awareness NZ group, has started an online petition calling for the suspension of Gardasil vaccination until various overseas actions, including legal cases against the vaccine supplier, "have been completely carefully analysed". The petition has more than 1500 supporters.
Internationally and in New Zealand, deaths and serious illnesses have been blamed on the vaccine.
However, the NZ Health Ministry says the vaccine has a "good safety profile".
More than 200,000 New Zealand females have received the vaccine since 2008. By last June, 568 cases of adverse reactions had been reported following vaccination, including 41 considered serious.
The ministry, citing overseas authorities and New Zealand's Medicines Adverse Reactions Committee, says they have found "no association between HPV immunisations and a range of health conditions including chronic fatigue syndrome, auto-immune conditions, multiple sclerosis, complex regional pain syndrome, postural orthostatic tachycardia syndrome and sudden death".