Five years ago, when actor Chadwick Boseman died at age 43 from colon cancer, it was a genuine shock. Last summer, when Catherine, Princess of Wales, was diagnosed with cancer at age 42, it was tragic, but it landed a bit differently. At that point, it was clear her diagnosis was part of a clear narrative: More and more relatively young adults are developing cancer.
But now, a more complicated story is emerging.
According to a new study published in JAMA Internal Medicine, some of the rise in early-onset cancer is a diagnostic mirage: Doctors are finding cases that would never have led to serious illness anyway. Younger adults — those under 50 — are indeed being diagnosed with cancer at nearly twice the rate they had been in 1990: 60 cases per 100,000 people, up from 30. But the number of metastatic cases, those that are more likely to be aggressive and/or were detected late, has not increased at nearly the same speed. The death rate for the eight cancers covered in the study has remained flat over the last 35 years.
“Overall, the rise in early-onset cancer appears to be less an epidemic of disease and more an epidemic of diagnosis,” the authors — researchers from Harvard, Brigham Women’s Hospital in Boston, and the University of Texas at Austin — write in their paper’s conclusion.
This surprised me. I’m a bit of a hypochondriac, and I’m an adult under 50, and so when I read a headline about the uptick of cancer among my own generation, I certainly think, Oh no, more young adults are getting sick and dying from cancer.
But there are ways to double-check that assumption — which is exactly what this new paper tries to do.
The authors decided to look deeper into the overall rising rate of cancer incidence among middle-aged adults and focus specifically on rates of metastatic cancer and death rates, metrics that correlate with more serious illness. And the findings suggest something else besides exposure to new toxins (whether pollution or ultra-processed foods or microplastics) could be contributing to the surge of cancer diagnoses among younger people.
It may be that at least part of the story is that we have simply improved our ability to detect cancer. That would frame the recent rise in cases a little differently: Perhaps cancer rates among relatively young adults are soaring because we are catching more cancers that were always out there but used to escape diagnosis, sometimes until it was too late.
That would be welcome news. But this is a complicated story. Let’s get into it.
How to think about this important new study on early-onset cancer
The new study examined eight categories of cancer that have been the fastest-rising over the past few decades: thyroid, colorectal, endometrial, kidney, anal, pancreatic, myeloma, and small intestinal. The combined incidence for those cancers has doubled since the 1990s — but the overall mortality rate has barely budged: 5.9 deaths per 100,000, identical in 2022 as it was in 1992.
This pattern is particularly apparent for breast cancer, still the most common form for people under 50. While the number of excess diagnoses compared to historical trends has increased substantially since the 1990s, the number of excess deaths compared to the historical average is actually down.
“The excess diagnoses similarly likely reflect the increased screening intensity in younger patients (i.e., more mammograms, ultrasonography, and magnetic resonance imaging) than an increase in the occurrence of clinically meaningful breast cancer,” the study’s authors write.
There is nuance to the findings: Death rates for colorectal cancers, the subject of much of the recent media coverage, and uterine cancers have noticeably increased over the study period, for example, even as mortality has fallen for other diseases. When I asked researchers who were unaffiliated with the findings, they emphasized that there are clearly at least some cancers that are genuinely becoming more common and leading to serious illness and death. Grouping all cancers together risks masking those more specific trends.
“I think we should focus more on the individual cancers and what’s going on with them and try not to lump them all together when making the overall inferences,” Timothy Rebbeck, a cancer researcher affiliated with Harvard and Dana Farber, told me.
He said the paper raised important points that should continue to be investigated, but added that “I hope the field and the public do not interpret this single paper as an indictment that increases in early onset cancer are either unimportant or not worthy of a better understanding.”
There are other limitations and alternative explanations for the study’s findings. For example, it is possible that perhaps we are getting more serious cancers earlier in our lives, but faster detection is preventing cases from becoming metastatic or leading to death. The flat mortality rates may also reflect the many improvements in cancer treatment, such as recent breakthroughs with immunotherapy drugs that have sent survival rates soaring.
The paper’s researchers argue against both. They point out that previous research into specific cancers, such as thyroid cancer, has already found evidence of overdiagnosis. On the possibility that serious cases are being caught earlier, the authors argue that we should then see a decrease in cancers diagnosed after age 50 — but that hasn’t happened.
But other experts do see the evidence differently: Rebbeck told me he thought that both improved treatment and earlier detection that staves off serious illness probably explain at least some of the study results. But we need to know more, he emphasized.
So what are we, the potential patients, to think about this? As a young person prone to health anxiety — I’m 37 — that is an urgent question to me.
First, one study is never the final answer in medical research. The findings here suggest overdiagnosis may explain some of the rise in early-onset cancer, but we need more research to be sure.
And second, people should be aware that certain cancers do appear to be occurring more frequently and with serious clinical consequences. You should know the colon and uterine cancer symptoms to watch out for, the risk factors to avoid — and, as always, talk with your doctor if you have concerns.
But it is worth asking ourselves whether we all need a mindset adjustment. This is not the first research to raise the possibility that we are too aggressive about diagnosing issues without a clear clinical imperative for doing so. I interviewed Dr. Suzanne O’Sullivan earlier this year, who wrote an entire book on the subject.
She wrote specifically about cancer overdiagnosis and the mental and financial burden placed on the patients who are told they have cancer, even if that cancer might not actually be a threat to their well-being, the kind of cases contemplated in this new study.
“Within the medical community, this has been well-known for a long time, but it just doesn’t leak into the general conversation,” she told me. “The bottom line is if you screen healthy people for an illness, any illness, be it cancer or high blood pressure, diabetes, then you will be picking up borderline cases and overtreating them.”
Doctors are under pressure to deliver concrete answers to patients, but even something like a cancer diagnosis — which feels like it should be black or white, yes or no — requires interpretation. A few abnormal cells on a scan or a blood test could be the start of a deadly tumor, or they might never develop into anything serious.
These findings are a reminder that detection is not the same as diagnosis — and while we have been conditioned to demand certainty from modern medicine, we ought to be aware of the uncertainties.
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