Cervical cancer is the fourth most common cancer for women yet the leading cause of cancer-related death in developing countries, an unfortunate statistic that highlights the importance of access to screening. Through a comprehensive trial involving thousands of subjects, a newly designed test has been found to greatly outperform current screening methods in terms of both cost and accuracy, while also shedding new light on the mechanics at play.
For a woman to develop cervical cancer, they must first be infected with the human papillomavirus (HPV). For this reason, current screening methods focus on detecting HPV through a Pap smear, where cells are collected from the cervix for examination, along with a more accurate HPV test that looks for the presence of HPV DNA.
Rather than inspecting the patient's genetic code for tell-tale signs of the HPV virus, scientists from Queen Mary University of London took a different approach. The method centers on epigenetics, a field of study that focuses on how external factors can bring out varying expressions of certain genes and change an organism, without altering the underlying DNA sequence itself.
In applying this to the problem of cervical cancer, the scientists designed tests that identified naturally occurring chemical markers on top of the DNA, creating an epigenetic profile of sorts. This screening method was applied to thousands of women in Canada aged between 25 and 65 alongside currently available screening methods, with the team following up five years later to compare the results.
The new epigenetics-based screening method proved successful in predicting 100 percent of the eight different types of cervical cancer to occur in 15,744 subjects. The Pap smear detected 25 percent of the cancers, while the HPV test detected 50 percent. In a subset of 257 HPV-positive women, the new test detected 93 percent of pre-cancerous lesions, compared to an accuracy of 86 percent provided by the Pap smear and HPV test combined.
"This really is a huge advance in how to deal with HPV-infected women and men, numbering in the billions worldwide, and it is going to revolutionize screening," says lead researcher Attila Lorincz. "We were surprised by how well this new test can detect and predict early cervical cancers years in advance, with 100 per cent of cancers detected, including adenocarcinomas, which is a type of cervical cancer that is very difficult to detect."
This new method could be a game changer when it comes to cervical cancer. Not only does it appear to be much more accurate, it would also be cheaper than a Pap smear if fully implemented, though the researchers don't expect that to happen for at least five years. But the research also has immediate implications, as it sheds new light on how cancers could be shaped by epigenetics, a scientific field we are learning more and more about all the time.
"This is an enormous development," says Lorincz. "We're not only astounded by how well this test detects cervical cancer, but it is the first time that anyone has proven the key role of epigenetics in the development of a major solid cancer using data from patients in the clinic. Epigenetic changes are what this cervical cancer test picks up and is exactly why it works so well. In contrast to what most researchers and clinicians are saying, we are seeing more and more evidence that it is in fact epigenetics, and not DNA mutations, that drives a whole range of early cancers, including cervical, anal, oropharyngeal, colon, and prostate."
The research has been published in the International Journal of Cancer.
Source: Queen Mary University of London
