Why Are More Young People Getting Cancer?

Ten years ago, Dr. Kimryn Rathmell, a kidney oncologist who was then at Vanderbilt University, noticed a startling trend: Many younger patients were coming to her with kidney cancer, including an 18-year-old with metastatic disease, which Dr. Rathmell had never seen in someone so young.

She assumed these patients had been disproportionately referred to big cancer centers like hers. But this spring, when researchers at the National Cancer Institute published a report showing that, between 2010 and 2019, rates of 14 cancers increased among people under 50 in the United States, the significance of her experience came into focus.

“I realized that what I was seeing was a trend that was happening everywhere,” said Dr. Rathmell, a former director of the N.C.I. who now leads the cancer program at Ohio State. The data were striking.