If you've ever had a pterygium—that fleshy, benign growth on the white of your eye—you probably weren't worried about cancer. But a new analysis of nearly 8,700 tissue samples suggests that about 1 in 75 pterygia actually contain a hidden, early-stage eye cancer called ocular surface squamous neoplasia (OSSN).
The study pooled data from 35 studies across the globe. Overall, 1.32% of pterygium specimens showed incidental OSSN. The risk wasn't random: people living closer to the equator had higher odds, and greater UV exposure more than doubled the risk. In South America, the hidden cancer rate was nearly 15%, while in Europe it was just 0.29%.
Importantly, the researchers found no differences in age, sex, or lesion location between benign pterygia and those hiding cancer. That means you can't tell by looking—only a lab test can. The evidence is considered low to very low certainty, so the true rate could be higher or lower. But the pattern is clear: UV exposure matters, and geography plays a role.
For anyone with a pterygium, especially in sunny regions, this is a reminder that what looks harmless may not be. Routine tissue analysis after removal could catch these hidden cancers early.