Statistics show a clear spike in eight cancers in younger people, but that has brought a debate over whether many cases ever needed to be found, reports The New York Times.
The statistics are incontrovertible: Since 1992, the diagnoses of eight cancers has doubled in the United States in patients under 50, including cancers in the thyroid, anus, kidney, small intestine, colorectum, endometrium and pancreas, as well as the blood cancer myeloma. Other types, including breast cancer, also are on the rise.
“The magnitude and speed at which early onset cancer incidence has increased is unlike most cancer trends ever observed (the possible exception being cigarette smoking and lung cancer),” the American Association for Cancer Research said in announcing a special conference this past weekend that explored the rise in cancers among younger people.
The sharp uptick has been agonising for these younger patients and many of their doctors.
The patients wonder: why did I develop cancer? And how will my life be transformed by potentially excruciating treatments?
Their doctors share these questions, and some have additional concerns: what if these cancers had never been detected? Are doctors offering treatments to younger patients with early-stage diseases that may do as much harm as good?
Outside exam rooms and clinics, many experts are debating the culprits of the spike. They are looking at environmental toxins, the obesity epidemic and changes in peoples’ microbiomes, perhaps from diets heavy in ultraprocessed foods. With rates rising so swiftly, they say, there is a compelling reason to find out why.
Some cancer specialists counter these concerns, saying the surge in diagnoses is primarily a surge in detecting cancers that did not need to be found, or did not need to be found so soon. They would not have killed patients if they had not been detected, or if they had been detected later in life.
It has been known for decades that not every cancer is dangerous. Some go away on their own. Others stop growing or pose no risk – they cause no symptoms and do not spread.
The idea that finding a cancer early is not always a good thing is not easy for many patients and their families to accept. And it is true that lives can be saved by treating cancer early.
Autopsy studies repeatedly find that many people die with small cancers of which they were unaware. A review of these studies in prostate cancer reported that the cancer can appear in men as young as their 20s. The older they were, the more likely they were to have undetected prostate cancer. By their 70s, about a third of white men and half of black men had undetected prostate cancer.
A study of thyroid cancer in Finland found that at least a third of adults had undetected tumours. Less than 1% of people with thyroid cancer die from it.
The problem is that it is impossible to know if someone’s cancer will be deadly or not. And if the cancer has gone after treatment, there is no way to know if it needed to be treated.
But there’s a way to know on a population level if an increase in diagnoses is a false alarm or a danger signal, said Dr H. Gilbert Welch of Brigham and Women’s Hospital of Harvard Medical School.
Look at the number of deaths from that cancer. If more lethal cancers are being found, there should be more deaths. But if the death rate remains steady as the incidence of that cancer spikes, many of those patients did not need to receive diagnoses.
That happened, for example, with thyroid cancer in South Korea. The incidence of thyroid cancer soared with the introduction of widespread ultrasound screening. But deaths did not increase. It was estimated that 90% of the cancers that were discovered and treated in women did not need to be found.
Well aware of such incidents, Dr Vishal Patel of Harvard, Welch, and Dr Adewole Adamson of Dell Medical School in Austin, Texas, asked whether the current spike in diagnoses in younger people of those eight cancers is tied to more deaths.
It is not, they reported in a recent paper examining trends over the past three decades.
For all but two of the eight cancers whose incidence has soared in younger people, death rates are flat or declining. Those two are colorectal and endometrial cancers.
Colorectal deaths are up by 0.5% a year, while their incidence is increasing by 2% a year. For endometrial cancer, the death rate and incidence rate seem to be in lock step, increasing by 2% a year.
Dr Elena Ratner, a gynaecological cancer specialist at Yale, attributes much of the increase of endometrial cancer to the obesity epidemic.
Dr Cary Gross of Yale, who co-wrote an editorial that accompanied Welch’s paper, said the increase in diagnoses might reflect more and better tests that are finding cancers unintentionally while looking for other conditions. The cancers in question, with the exception of colorectal, are not part of routine cancer screening.
But scans and a routine blood test are finding cancers by coincidence.
CT, ultrasound and MRI scans are increasingly sensitive and more frequently used, Gross said.
“We are a very imaging-happy society,” he said.
Welch and his colleagues echoed that sentiment in their paper. “The epidemic narrative not only exaggerates the problem, but it may also exacerbate it. While more testing is often seen as the solution to an epidemic, it can just as easily be the cause.”
Treatments can save lives, but he and his colleagues say that treatments need to be balanced with the consequences of finding a cancer that did not need to be found. Patients having unnecessary cancer treatments may face infertility and organ damage. The cost of the treatments can be expensive, and so can surveillance, follow-up care and management of adverse side effects.
Welch said the number of unnecessary diagnoses could be lessened if doctors did less routine testing – and if doctors held back from pursuing every abnormality in asymptomatic patients.
“Abnormality is a normal part of life,” he said.
But that view is challenged by experts who see the explosion in diagnoses as a warning. With rates rising so swiftly, they say, there is a compelling reason to find out why.
“Something very interesting is going on here,” said Timothy Rebbeck, an epidemiologist and geneticist at the Dana-Farber Cancer Institute in Boston and a co-chair of the American Association of Cancer Research’s conference this week.
And, he added, “it’s not good.”
The surge in cases is of grave concern, said Dr Julie Gralow, chief medical officer at the American Society of Clinical Oncology. “I’m saying its real and it’s serious. And we need to understand why.”
Dr Kimmie Ng, a colorectal cancer specialist at Dana-Farber, said she was seeing more younger patients with colorectal cancer. Many had symptoms, she said – their cancers were not found by chance.
Investigators, she added, are studying patients’ microbiomes and the environment for clues.
One reason there has not been an increase in cancer deaths, Gralow said, is that better treatments are saving lives.
“We absolutely have had major advances in treating many cancers,” she said.
Whether to treat cancer early may depend on its type. Some, like prostate and thyroid cancers, tend to be indolent. For those, patients with early-stage cancers might safely wait to see if their cancer progresses.
That’s a lesson that was learned by prostate specialists after there was an alarming surge in cases when doctors began offering men a blood test, the PSA, to detect prostate cancer. Rates skyrocketed, increasing by more than three fold from 1987 to 1992.
Many men were treated aggressively with surgery or radiation after doctors found small tumours in their prostates. But the increased detection did not lead to an increased death rate.
Eventually, many prostate cancer experts agreed there was no epidemic of prostate cancer. There was an epidemic of detection.
Now prostate specialists are more likely to advise men with a low-risk diagnosis – which account for more than 50% of recent prostate cancer cases – to forgo treatment and have regular monitoring. They can have treatment if their tumours start to grow.
See more from MedicalBrief archives:
Cancer’s most promising treatments constrained by lack of action
Getting to the bottom of cancer rise among young people
Global quest to pinpoint cause of early-onset cancers