The End Of Cervical Cancer?
Some fantastic news about vaccines
There’s no two ways about it: cancer is shit. There are thousands of diseases that make up the thing that we collectively describe as cancer, and while they are all incredibly diverse they all have one thing in common, which is that they all really, really suck.
For everyone who hates cancer, there’s some fantastic news out recently. Cervical cancer, a pretty nasty disease that kills many thousands of women each year, may be gone for good within our lifetimes. It’s genuinely nothing short of a miracle.
The Science
In the late 90s and early 00s, scientists had a great idea - “what if we developed a vaccine the prevented cancer?”. And, after being informed that we already had one - the hepatitis B vaccine, which prevents liver cancer - they said “well what if we had another one?”. We knew by then that the disease human papillomavirus - HPV, which causes warts on the genitals and elsewhere in the body - caused most cases of cervical cancer in humans. We also knew that it was in theory possible to prevent diseases like this from infecting humans using vaccines, because it had been done many times before.
Putting these two together, we developed the HPV vaccine in 2006. The full story is well worth reading if you’ve got the time, but basically it involves identifying which types of HPV cause cancer (out of the 100 or so different strains), and figuring out how to prevent those in humans without making them sick in other ways.
At the end of the day, we were left with a vaccine that stopped most of the cancer-causing types of HPV, which we believed would then go on to prevent cervical cancer in people who got it. The one downside is that cervical cancer takes years to develop, so while the first youths got the HPV vaccine way back in 2006/7, we had to wait for a long time to see the results in cervical cancer rates in adult women.
But we are now seeing the results, and they are genuinely wonderful.
The Results
There are now quite a few studies showing that rates of cervical cancer are down quite a bit in women who got the vaccine compared to women who didn’t. A recent study from the US showed that while cervical cancer rates overall have remained fairly steady in the last decade, rates in younger vaccinated women have dropped by 65% while rates in older unvaccinated women have increased slightly by about 1.7% per year. This effect carries forward as women age, with 25-29 year old women - who would’ve been 11-15 in 2006 - starting to see declines in the rate of cervical cancer only in 2019.
Even more amazingly, a new Scottish study has just come out which found that in women who had been vaccinated at the age of 12-13 years, there were no cases at all of cervical cancer. In other words, women who were vaccinated before they were sexually active may be at no risk from cervical cancer. Pretty impressive stuff.
The study also showed that even in women who had been vaccinated a bit later in life there was a significant protective effect, even after controlling for confounding factors such as age and deprivation.
Another Swedish study from 2020 looked at the same question, and found that the rates of cervical cancer were more than halved in women who had been vaccinated when they were younger. After looking at a range of factors that could cause lower rates of cancer, the Swedish study found that women who had been vaccinated were 88% less likely to get cervical cancer, from about 1 case per 1,000 in unvaccinated people to 1 case per 10,000 when vaccinated.
While this sort of study is observational and therefore limited in terms of causal inference - we can’t say for sure that the vaccine is causing all of this reduction in cervical cancer - the combined evidence is very convincing. There is increasingly strong evidence that cervical cancer will be gone within our lifetimes, which is nothing short of miraculous.
The End of Cervical Cancer
Getting to this point has been a hard slog. Despite enormous, well-controlled studies showing that the HPV vaccine was safe and effective, anti-vaccine advocates have spent the last two decades arguing against it. There has been a massive effort to argue that vaccinating young women will make them more likely to have sex, even after evidence has come in showing that this is extremely unlikely to be true. Anti-vaccine advocates have spent years trying to say that HPV vaccination will harm fertility, even though this is certainly false.
Thankfully, after a huge public health effort, we are now reaping the benefits of effective vaccination. It’s quite likely that cervical cancer will soon mostly be a thing of the past. In addition, the many other cancers that HPV causes - including anal, oral, and other cancers - are rapidly becoming less and less common in vaccinated age groups.
It’s not often that I write such a positive blog, but this is just a great achievement that we should all be proud of. Vaccines are amazing, and together we may have almost entirely eliminated a horrible disease. It’s brilliant news.