New research suggests one reason for this change may be that younger generations are aging faster on a biological level than previous generations.

A study published in Nature Medicine found that younger generations showed signs of accelerated biological aging compared with people born decades earlier. Researchers also discovered that this faster aging is linked to a greater risk of developing early-onset cancers, particularly cancers of the lung, digestive system, and uterus.

“Right now, we don’t have a definitive answer to what’s driving the rise of early-onset cancers around the world, but studies like this are helping us piece together the bigger picture, showing that cancer may be influenced not just by changes inside individual cells, but by wider changes happening across the body as a whole,” said David Scott, director of Cancer Grand Challenges, in a press release.