Scientists have discovered that cervical cancer can be divided into two distinct molecular subgroups – one far more aggressive than the other – offering hope of better understanding and treatment of the disease.
In the United Kingdom, there are over 3,000 new case of cervical cancer, with around 850 deaths each year. It is almost always caused by the human papillomavirus (HPV), and vaccination against this virus has successfully reduced the incidence of cervical cancer – in fact, the reduction has been by 87% among women in their 20s in England who were offered the vaccine when they were aged 12-13 years as part of the U.K. HPV vaccination program.
“Despite major steps forward in preventing cervical cancer, many women still die from the disease,” said Tim Fenton, MD, associate professor in cancer biology, School of Cancer Sciences Centre for Cancer Immunology, University of Southampton (England), and coauthor of the new study.
Two distinct subgroups
In the new study, published in Nature Communications, researchers described their breakthrough findings as a “major step forward” in understanding the disease, and said they provided a “tantalizing new clue” in determining the best treatments for individual patients.
For the observational study - part of the largest ‘omics’ study of its kind – researchers led by scientists at University College London and the University of Southampton began by applying a multiomics approach to identify combinations of molecular markers and characteristics associated with the biological processes involved in cervical cancer cells. The integrated multiomic analysis of 643 cervical squamous cell carcinomas (CSCC) – the most common histological variant of cervical cancer – represented patient populations from the United States, Europe, and sub-Saharan Africa.
To begin with they analysed and compared DNA, RNA, proteins, and metabolites in 236 CSCC cases in a publicly available U.S. database. They found that U.S. cancers fell into two distinct “omics” subgroups, which they named C1 and C2. After further investigation, the researchers identified that C1 tumors contained a much higher number of cytotoxic T cells. “The findings suggested that patients with C1 tumors would have a stronger immune response within the tumor micro-environment,” they said.
Weaker antitumor immune response
To determine if the two sub-types affect patients with cervical cancer in different ways, the team, which also included researchers from the University of Kent, the University of Cambridge, Oslo University Hospital, the University of Bergen (Norway), and the University of Innsbruck (Austria) derived molecular profiles and looked at clinical outcomes of a further 313 CSCC cases from Norway and Austria.
The researchers found that, just as in the US cohort, nearly a quarter of patients fell into the C2 subtype, and that again C1 tumors contained far more killer T cells than C2 tumors. “Importantly, the data also showed C2 was far more clinically aggressive with worse outcomes for patients,” the authors said.
Patients with C2 tumors were more than twice as likely (hazard ratio, 2.32) to die from their cervical cancer at any point during the follow-up period – up to 21 years – than those with C1 tumors. In terms of 5-year disease-specific survival, the rates were 79% survival for C1 and 66% survival for C2, the authors pointed out.
They highlighted that the difference in outcomes between patients with C1 and C2 tumors was very similar across the US and European cohorts.
Kerry Chester, PhD, professor of molecular medicine at UCL Cancer Institute, and coauthor, said: “Inclusion of patient cohorts in Norway and Austria, for which highly detailed clinical information was available to complement the molecular data, were key factors in the success of the study.”
Analyzing a further cohort of 94 Ugandan CSCC cases, the team found that C2 tumors were much more common than C1 tumors in patients who were also HIV-positive, “underlining the link to a weaker antitumor immune response” in this group.