Cancer Rates In Young People
Explaining the recent news about more cancer in people under 50
This week, there have been a swathe of scary new headlines about cancer in young people. If you’ve been paying attention to the news, rates of cancer in people under the age of 50 have been skyrocketing over the last decade, a trend that is as mysterious as it is scary.
But if you read the underlying research, the story isn’t so much scary as it is fascinating. This is the sort of research that is incredibly useful for public health experts, but it doesn’t necessarily mean all that much to the average person.
Let me explain.
The Research
The study that’s been causing all of these scary headlines is a fairly simple epidemiological paper looking at cancer diagnoses in the United States from 2010-2019. The authors took a large national database of cancer diagnoses across the US, and used this to calculate the yearly incidence - an epidemiological term meaning new diagnoses - per year, and then looked at the trends by type of cancer and demographic information for people under the age of 50.
What they found was that, between 2010 and 2019, there was a yearly increase in the incidence of all cancers in this age group. In 2010, about 100 people per 100,000 aged 0-49 were diagnosed with a new case of cancer, and by 2019 this had increased to 103 per 100,000. This was calculated as an annual 0.28% increase in the rate of any cancer diagnosis in young people in the US.
This is actually not a new finding. There have been a number of studies showing that certain types of cancer - particularly cancers in the gastrointestinal tract - have been on the increase in younger people for some time. We’ve seen rises across the world in young people for colorectal cancer, for example, for a while already.
And that’s where all of the scary headlines are coming from - young people today are more likely to be diagnosed with cancer than they were a decade ago. That’s certainly an issue, but there’s some important context that’s worth noting before you start stressing about cancer in under-50s.
The Context
The first important thing to note is that this rise in cancers is not universal. Have a look at the below image take from the study:
This shows the rates of cancer (yellow, on the left) in 2010 vs the rates (grey, on the right) in 2019, broken down by demographics and type of cancer. What you can see is that there are many differences here. Cancer rates rose in young women, but fell slightly in young men. There were more cases of breast and gastrointestinal cancers, but fewer brain, lung, and blood cancers. While there were overall more new cancers in young people, that was not consistent across the board.
More importantly, these changes were really small. The rate of new cancers increased by 3% overall, but this amounted to only an additional 600 cancers per year. Of those new cases of cancer, most were breast or colorectal cancers in people aged 30-39.
In fact, the increase in cancers in young people was so small that it was completely unnoticeable in the broader population - cancer incidence has actually fallen overall in the US for decades. While the number of cancers has gone up slightly in young people, it has fallen far more in older people. Since young people make up a minority of total cancer cases (~25%), the fact that there’s been a 3% increase in cancer incidence in young people is vastly overshadowed by a 9% decrease in older people. Overall, this means that the net rate of new cancer diagnoses across the US has fallen by about 7% in the US since 2010.
On top of that, cancer survival rates continue to improve across the board. So while young people are slightly more likely to be diagnosed with cancer than they were a decade ago, they are also much more likely to live through that experience.
Underlying Causes
At an individual level, these slow changes to cancer incidence and mortality aren’t that impactful. Unless you’re an epidemiologist or similar, you aren’t going to see this sort of change in your daily life.
But it is true that this is a bit concerning for epidemiologists, because we aren’t really sure why this shift is happening. A slow increase in cancer rates for young people isn’t particularly alarming when cancer rates overall are declining, but it’s possible that this is just a function of time. If people who are 30-39 now are still at an increased risk when they turn 60, a small problem may suddenly become a much larger issue.
People like me are going to keep an eye on these changes. They’re fascinating, and there may be things that we can do to prevent some of these people getting cancer in the future.
But the headlines probably don’t mean all that much to you. Small, slow changes to population cancer rates are important at a grand scale, but don’t impact daily existence for most people living out their lives.
I wonder how much of this is due to young people having insurance that covers preventive visits after 2010.