A rise in cancer rates

Since 1992, the number of diagnoses of eight cancers in U.S. patients under 50 has doubled, including cancers in the thyroid, anus, kidney, small intestine, colorectum, endometrium, and pancreas.

"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 (AACR) said.

Many experts are debating the cause of the spike in cancer rates, examining environmental toxins, the obesity epidemic, and changes in peoples' microbiomes, potentially from diets heavy in ultra-processed foods, Kolata reports.

Some cancer specialists have countered those concerns saying the surge in cancer diagnoses is a result of detecting cancers that didn't need to be detected — or at least didn't need to be detected so soon — as they wouldn't have killed patients had they never been found or if they'd been found later in life.

Not every cancer is dangerous — some disappear on their own while others stop growing or pose no risk to the patient, Kolata reports.

Autopsy studies have found many people die with small cancers they never knew about. One review of these studies in prostate cancer found the cancer can appear in men as young as their 20s. The older the men were, the more likely they were to have undetected prostate cancer, and by their 70s, around a third of white men and half of Black men had undetected prostate cancer.

Similarly, a study of thyroid cancer in Finland found that at least a third of adults had undetected tumors. Less than 1% of people who have thyroid cancer die from it.

However, it's impossible to know if a person's cancer will be deadly or not, and if the cancer is gone after treatment, there's no way to know if the treatment was actually necessary.

But according to H. Gilbert Welch of Brigham and Women's Hospital at Harvard Medical School, there's a way to know at a population level if an increase in diagnoses is either a false alarm or a signal of something dangerous. If more lethal cancers are being found, then death rates should be rising, but if death rates remain steady while cancer rates rise, many of those patients didn't need to receive diagnoses, Welch said.

That happened in South Korea with thyroid cancer, as rates of the cancer skyrocketed with the introduction of widespread ultrasound screening, but death rates didn't. It was estimated that 90% of the cancers detected and treated in women didn't need to be found.

Welch, alongside Vishal Patel from Harvard and Adewole Adamson from Dell Medical School, found something similar, reporting in a recent paper looking at trends over the past 30 years that the current spike in cancer diagnoses in younger people in the eight previously mentioned cancers was not tied to an increase in deaths.

In an editorial accompanying Welch's paper, Cary Gross from Yale said the increase in cancer diagnoses could reflect an increase in testing, as well as better quality tests that are finding cancer unintentionally while looking for other conditions. These cancers, with the exception of colorectal cancer, are not part of routine cancer screenings, but scans and routine blood tests are finding cancers by chance.

In addition, CT, ultrasound, and MRI scans are increasingly sensitive and used more frequently, Gross said. "We are a very imaging-happy society."

Welch and his colleagues had similar conclusions 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," they wrote.

"Something very interesting is going on here," said Timothy Rebbeck, an epidemiologist and geneticist at the Dana-Farber Cancer Institute. And, he added, "it's not good."

According to Julie Gralow, CMO at the American Society of Clinical Oncology, the surge in cancer rates is of grave concern. "I'm saying it's real and it's serious," she said. "And we need to understand why."

Kimmie Ng, a colorectal cancer specialist at Dana-Farber, said she's seeing more younger patients with colorectal cancer. Many of those patients had symptoms and their cancers weren't just found by chance, she said.

Ng added that investigators are studying patients' microbiomes and their environments for clues.

Gralow noted that one reason there hasn't been an increase in cancer deaths is because better treatments are saving lives.

"We absolutely have had major advances in treating many cancers," she said.

Whether a cancer should be treated early on could depend on its type. Some cancers, like prostate and thyroid, tend to be indolent, meaning patients with early-stage cancer could simply wait and see if their cancer progresses.

That was a lesson learned by prostate cancer specialists after a three-fold surge in cases occurred between 1987 and 1992 after doctors started offering men a blood test to detect the cancers. Many of those men treated the cancer aggressively with surgery or radiation, but the increased detection didn't lead to an increased death rate, and many prostate cancer experts eventually agreed there wasn't an epidemic of prostate cancer but rather an epidemic of detection.

Now, prostate cancer specialists are more likely to advise men with a low-risk diagnosis, which accounts for over half of recent prostate cancer cases, to forgo treatment and have regular monitoring to see if their tumors grow.

Jamie Rigal was 31 when a blood test determined he had prostate cancer. Rigal said he consulted with doctors at some of the best cancer centers in the country, and at one of them, he was told he needed aggressive therapy or he would die of prostate cancer.

But Rigal's doctor, Leonard Marks, a prostate specialist at the University of California, Los Angeles, urged Rigal to forgo treatment and regularly monitor his cancer to see if it was progressing.

Marks found cancer twice on biopsies after Rigal's initial test and then never saw it again. Rigal's blood test results became normal and have remained normal, as have his biopsies. It's been 20 years since Rigal's diagnosis, and two recent MRIs didn't detect any cancer.

Rigal said now he goes in every two years for testing and otherwise tries to put cancer out of his mind.

"I kind of take a mental health approach," he said. "I take it year by year."