Human papillomavirus (HPV) vaccination and HPV-based screening programs are key to preventing cervical cancer, research has shown, but some people are missing out.
HPV can be found in close to 93 per cent of cervical cancers using standard laboratory methods, highlighting the importance of Australia’s vaccination and screening programs, according to a report published in the Medical Journal of Australia on Monday.
Possible explanations for HPV-negative cervical cancers include: Misdiagnosed uterine or other cancer types, failed detection of HPV, loss of HPV DNA over time, or HPV never being present, the authors led by Associate Professor Julia Brotherton, medical director of the VCS Foundation’s Population Health division, wrote.
A rare subset of cervical cancers – gastric type adenocarcinomas – are known to develop without HPV, and may be caused by mutations of p53, a gene that regulates the cell cycle and, when functioning normally, acts as a tumour suppressor.
The underlying rate of cancers that are truly HPV-negative, and in which HPV was not involved in the cancer development, is “very small”, the authors wrote, estimating that up to 90 per cent of adenocarcinomas and close to 100 per cent of squamous cancers are originally caused by oncogenic HPV.
“HPV vaccination and HPV-based screening offer effective methods of preventing most cervical cancers,” they concluded.
Doctors warn of barriers to screening
The report comes as researchers warn that women who have sex with women (WSW), trans men and non-binary people with a cervix are at similar risk of human papillomavirus (HPV) infection and subsequent risk of developing cervical cancers as heterosexual women, but are often never screened or underscreened.
Dr Monica McGauran and Dr Adam Pendlebury, from the Mercy Hospital for Women in Melbourne, reported the case of a 39-year-old woman who was referred for colposcopy with a positive human papillomavirus (HPV) type 16 infection result on a self-collected HPV vaginal swab.
She was asymptomatic and was overdue by many years for cervical
“Barriers to regular cervical screening were cited as having difficulty with speculum examination and having a female partner, with the subsequent perception that cervical screening was not required,” Dr McGauran and Dr Pendlebury wrote in the Medical Journal of Australia.
“HPV can be transmitted intravaginally between female sexual partners via digital contact and fomites, such as sex toys.
“In addition, a proportion of WSW have had previous or have current male sexual partners.”
The authors cited 2001 research that found 10 per cent of WSW had been told by health care practitioners they did not need to be screened if they did not have sex with men.
“Other reasons for reduced uptake [of screening] included lower perceived level of risk for HPV infection, provision of health care that was not sensitive or inclusive to non-heterosexual women, and reduced provision of opportunistic health care due to the reduced need for contraception,” Dr McGauran and Dr Pendlebury wrote.
Self-collected samples are now available as part of the National Cervical Screening Program for women over the age of 30 years who have never been screened or who are overdue for screening by two or more years.
It is available to be collected in a practitioner-supervised setting (ie, not at home) and is not available to women who are pregnant, symptomatic, or who have a past history of dysplasia.
Self-collected swabs are “as sensitive as practitioner-collected samples” and present an “excellent option for never-screened and underscreened women, transsexual men and non-binary people with a cervix who are aged 30 years and older and who decline practitioner collection”, Dr McGauran and Dr Pendlebury said.