This article was first published in the Montreal Gazette.
You may have recently heard about an analysis from Scotland involving the ability of the HPV vaccine to prevent cervical cancer. This time, the results justify the headlines. The analysis found zero cases of cervical cancer in women vaccinated at a young age. Such results can make even the most cynical among us believe we can achieve the World Health Organization’s goal of eliminating cervical cancer by 2030.
The mere fact that we can talk about its elimination is incredible to me. Cervical cancer, once a major cause of cancer deaths in women, has been decreasing steadily for decades due in no small part to the advent of the Pap smear by Georgios Papanikolaou. But in recent years, the development of the HPV vaccine has made it possible to imagine a world where cervical cancer is all but eliminated.
Since the vast majority of cervical cancer cases are caused by infection with the human papillomavirus (HPV), a vaccine that prevents infection can therefore prevent the development of cancer.
The benefits of the HPV vaccine are, at this point, beyond doubt. Randomized controlled trials like FUTURE I and FUTURE II and Cochrane reviews of the data have demonstrated the vaccine’s ability to prevent the many diseases caused by HPV infection.
What’s more, the vaccine has gone through a few updates over the years. The initial bivalent vaccine protected against HPV-16 and HPV-18, the two types of HPV most usually associated with cervical cancer. New formulations expanded the protection to four and then nine types of HPV. But the first cohort of women and girls to receive the HPV got the original bivalent vaccine and now, 15 years after the fact, we are starting to see the benefits.
The most recent Scottish analysis echoes prior publications from England and Sweden and shows how a successful population-wide vaccine rollout can prevent cancer and save lives. But the Scottish experience garnered headlines because of the finding that the group of girls vaccinated at 12 and 13 years of age had zero cases of cervical cancer.
The age of vaccination is important. Since HPV is transmitted sexually, vaccination prior to the onset of sexual activity is key. You can still benefit if you are vaccinated later, and vaccination in 14- to 22-year-olds reduced the incidence of cervical cancer in Scotland from 8.4 to 3.2 cases per 100,000.
But even with the original bivalent vaccine, which was in use when these women were vaccinated as girls, the benefits are striking and make talk about cervical cancer eradication possible.
We may never achieve absolutely zero cases as the vaccines do not protect against all types of HPV — only those that are most associated with cancer. But if we can meet the World Health Organization goal of 90 per cent vaccination coverage in girls by age 15, we can probably achieve the target of fewer than four cases per 100,000 per year.
This obviously has to be coupled with proper cancer screening and treatment. In the developed world this is easy, but in many countries limited resources make this difficult. Achieving vaccination, screening and treatment targets of 90 per cent, 70 per cent and 90 per cent, respectively, by 2030 is the new global target. Whether we will achieve this or not will depend on our ability to mobilize resources globally, not just locally.
In the developing world, limited resources are the problem. But in the developed world, misinformation is our weak spot. Infamously, the Toronto Star published a headline about the “dark side” of the HPV vaccine before retracting the story when many experts pointed out that many of the claims in the story were not supported by evidence.
HPV vaccination has the potential to prevent cancer, not just catch it early. It will take money and resources to meet the WHO targets by 2030. But as they say, an ounce of prevention is worth a pound of cure.
