Why are so many young people getting cancer? What researchers do and don't know

A 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. Landmark cancer trial shows success against ‘undruggable’ cancer — raising hopes for future treatments “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. …