Anal cancer rates in the UK have increased by nearly 300 per cent over the last 40 years, according to new figures* published by Cancer Research UK.
And the increase in cases has been dramatically higher in women (374 per cent) than in men (202 per cent) over this period, rising from 0.4 to 1.8 per 100,000 in females compared to 0.4 to 1.2 per 100,000 in males.
Experts believe the reason for the dramatic rise is likely to be caused by the increasing prevalence of the human papillomavirus (HPV), a virus that is usually transmitted through sexual activity. An estimated 90 per cent of anal cancer cases in the UK are linked to HPV infection.
Overall the rates have risen from 0.4 in every 100,000 in the mid 70s to 1.5 today. Anal cancer is relatively rare, but awareness of the disease is low as it is still considered taboo by many.
“These are very worrying findings and highlight an increase in a cancer that’s not often talked about.” – Nick Ormiston-Smith, Cancer Research UK
Previous research into sexual attitudes and lifestyles**** has suggested more heterosexual couples are having anal intercourse, which might account for the higher rates of the disease in women. But HPV is a very common virus and any sexual activity can increase the risk of passing on the infection to a partner.
Smoking may also be a risk factor for the disease and, though smoking rates have dropped since the 1970s, the drop has been smaller in women than in men, and slower in younger age groups where anal cancer is more common.
Nick Ormiston-Smith, Cancer Research UK’s head of statistics, said: “These are very worrying findings and highlight an increase in a cancer that’s not often talked about. Around 1,200 people are diagnosed with cancer of the anus every year in the UK, which means it’s still a relatively rare disease. But the rise in incidence, particularly in women, is concerning.
“We don’t fully understand the reason for the difference between men and women, but we do know HPV and smoking are strong risk factors for the disease.”
The introduction of the HPV vaccine for girls has been an important public health measure and is expected to help reduce the rates of HPV-related cancers in the UK in the future. The Joint Committee on Vaccination and Immunisation (JCVI) is now considering whether to extend the vaccination programme to boys, as rates of HPV-related cancers are also on the increase in men.
Using a condom also reduces the risk of spreading the infection, but it doesn’t completely prevent it from being passed on to a partner.
Jessica Kirby, senior health information manager at Cancer Research UK, said: “Anal cancer is closely linked to HPV, and changes in sexual attitudes mean people are increasingly exposed to the virus. We’re not suggesting people take a vow of celibacy, but HPV vaccination, using a condom and being a non-smoker can all help to reduce the risk.
“Early diagnosis is also important so report any unusual or persistent changes in your body or bowel habits to your doctor. The most common symptom is bleeding from the anus. The cause is much more likely to be something less serious but it’s important to report symptoms to your doctor and get them checked out.”
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*To remove the effects of random variations in rates from year to year the percentage change in rates since the mid 1970s is based on European age-standardised incidence rates for 1975-1977 and 2009-2011. Incidence rates in those periods are shown below.
Great Britain – All ages
**Based on the annual average age-standardised mortality rate for anal cancer (ICD-10 C21) increasing from 0.08 in 1975-77 to 0.34 in 2009-10 in the UK. This is an increase of 344 per cent.
***Based on 299 people dying from anal cancer (ICD-10 C21) in the UK in 2011.
****Natsal-3 research shows increasing prevalence of anal sex over time in men and women: http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)62035-8/fulltext