For decades, cancer research has treated biological sex as a background variable — a demographic footnote rather than a molecular force. A team at Sanford Burnham Prebys Medical Discovery Institute has now shown, through the lens of proteomics, that sex actively reshapes the protein landscape of tumors, most dramatically in lung adenocarcinoma, where 901 proteins differ in abundance between male and female patients. The finding invites medicine to reconsider what precision truly means: not merely matching a drug to a mutation, but understanding that the same cancer, in different bodies, may be