GoKawiilA woman receives chemotherapy.Credit: Ricky Carioti/The Washington Post/Getty
Researchers around the world are grappling with a vexing problem: why are so many young people developing cancers once considered the purview of old age?
The question was prominent at two of the world’s largest cancer meetings this year, and hypotheses abounded. Ultra-processed foods, obesity, microbial toxins and agricultural chemicals were all considered. But a clear answer remained elusive.
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“Multiple cancers are increasing in incidence globally among individuals under the age of 50,” oncologist Kimmie Ng told the audience at the American Society of Clinical Oncology meeting in Chicago, Illinois, last week. “The vast majority are considered sporadic, with unknown cause.”
Worldwide, more than 9,000 cases of cancer are diagnosed in adults under the age of 50 each day, epidemiologist Hyuna Sung told the American Association for Cancer Research (AACR) annual meeting in San Diego, California, in April. But lumping these diagnoses together could obscure clues as to their cause, she cautioned. “Rising incidence of cancers among young adults does not reflect a single story,” said Sung, who works at the American Cancer Society in Atlanta, Georgia.
Disparate causes
Clues to each story lie in the data. If diagnoses of a particular cancer increase suddenly and across all age groups, for example, the culprit might be a change in how that cancer is detected or classified. In the early 2010s, for example, the definition of pancreatic cancer was expanded to include pancreatic neuroendocrine tumours, which form in the pancreas’s insulin-making regions. Pancreatic cancer diagnoses had been slowly rising in the years before that change, but after it, the increase accelerated, including in people under the age of 50.
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The classification change probably does not fully explain the rise in early-onset pancreatic cancer, says Sung, but it probably accounts for much of it.
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