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Cervical cancer study suggests ‘global elimination is within reach’
A rapid scale-up of HPV vaccination and screening could effectively eliminate cervical cancer as a major public health problem in most countries by 2100, according to a modelling study published in Lancet Oncology.
“Despite the enormity of the problem, our findings suggest that global elimination is within reach with tools that are already available, provided that both high coverage of HPV vaccination and cervical screening can be achieved,” Karen Canfell, DPhil, director of the cancer research division at Cancer Council New South Wales and adjunct professor at University of Sydney, said in a press release. “More than two-thirds of cases prevented would be in countries with low and medium levels of human development, like India, Nigeria and Malawi, where there has so far been limited access to HPV vaccination or cervical screening.”
The director-general of WHO issued a call to action in 2018 toward global elimination of cervical cancer, the fourth most common cancer among women. The organization specifically has called for an expansion of HPV vaccination, screening and treatment of precancer, early detection of invasive cancers, and palliative care services.
About 85% of the estimated 570,000 cervical cancer cases diagnosed globally in 2018 occurred in lower-income countries. HPV vaccines can prevent as many as 90% of cervical cancers, but fewer than 3% of females aged 10 to 20 years in low- and middle-income countries received the full course of vaccination in 2014, compared with more than 30% in high-income countries, according to study background.
Projecting the effects of action
Canfell and colleagues conducted a statistical trend analysis and modelling study to quantify the possible cumulative effect of improved screening and vaccination coverage on cervical cancer cases avoided from 2020 to 2069.
The researchers used high-quality registry data in the Cancer Incidence in Five Continents series produced by the International Agency for Research on Cancer to analyze trends in cervical cancer worldwide. They used the Policy1-Cervix simulation platform to conduct a dynamic, multicohort modelled evaluation of the effects of possible scale-up efforts on cervical cancer prevention. This enabled them to predict the future prevalence and burden of cervical cancer globally, by Human Development Index (HDI) category (low, medium, high and very high) and at the individual country level.
The analysis indicated that without further intervention, 44.4 million cervical cancer cases would be diagnosed between 2020 and 2069, with nearly two-thirds of these cases in low- or medium-HDI countries.
A prompt escalation of vaccination to 80% to 100% coverage globally by 2020 using a broad-spectrum HPV vaccine could prevent 6.7 million to 7.7 million cases during this time. However, the researchers project that more than half of these cases will be prevented after 2060.
The introduction of twice-in-a-lifetime HPV-based screening, at ages 35 and 45 years, in all low- and middle-income countries with 70% coverage globally is expected to prevent another 5.7 million to 5.8 million cases in the next 50 years.
Rapid expansion of both high-coverage screening and vaccination beginning in 2020 would reduce average cervical cancer incidence to less than six new cases per 100,000 women annually by 2045 to 2049 in very high-HDI countries (including the United States, Finland, the United Kingdom and Canada), by 2055 to 2059 in high-HDI countries (including Mexico, Brazil and China), by 2065 to 2069 in medium-HDI countries (including India, Vietnam and the Philippines), and by 2085 to 2089 in low-HDI countries (such as Ethiopia, Haiti and Papua New Guinea).
The expansion strategy would lower cervical cancer incidence to less than four new cases per 100,000 women by 2055 to 2059 in very high-HDI countries, by 2065 to 2069 in high-HDI countries, by 2070 to 2079 in medium-HDI countries, and by 2090 to 2100 or beyond in low-HDI countries.
However, the researchers noted that this rate would not be attained in all low-HDI countries (including Tanzania, Kenya and Uganda) by the end of the century.
A more gradual expansion of vaccination and screening — such as 20% to 45% vaccination coverage and 25% to 70% once-per-lifetime screening coverage by 2030, increasing to 40% to 90% vaccination coverage and 90% screening coverage by 2050 — could reduce incidence rates by 2100 to a lesser extent. The result would be a decrease in average cervical cancer rates to 0.8 cases per 100,000 in very high-HDI countries, 1.3 per 100,000 in high-HDI countries, 4.4 per 100,000 in medium-HDI countries, and 14 per 100,000 in low-HDI countries.
‘Enormous opportunity’
“The WHO’s call to action provides an enormous opportunity to increase the level of investment in proven cervical cancer interventions in the world’s poorest countries,” Canfell said in the press release. “Failure to adopt these interventions will lead to millions of avoidable premature deaths.”
The modelling study will guide WHO’s global strategy to expedite cervical cancer elimination, which will be presented for consideration by the World Health Assembly in May 2020, Marc Brisson, PhD, full professor and leader of the research group in mathematical modeling and health economics of infectious diseases at Laval University, and Mélanie Drolet, PhD, epidemiologist and senior research associate at Laval University, wrote in a related editorial.
“The key contribution of the study by Simms and colleagues is that it provides the first evidence of the potential for global cervical cancer elimination as a public health problem,” they wrote. “The article also represents a strong example of the role mathematical modelling can have in informing policy decisions.” – by Jennifer Byrne
Disclosures: Simms reports grants from the National Health and Medical Research Council during the conduct of the study. Please see the study for all other authors’ relevant financial disclosures. Brisson reports involvement in the WHO-driven cervical cancer elimination modelling project, but no role in the development of the article by Simms and colleagues. Drolet reports no relevant financial disclosures.