Study summary

A tumor's molecular profile can safely guide who needs radiation after surgery

PORTEC-4a trial · Phase 3, randomized · Published January 2026, Lancet Oncology

What was tested

Treatment chosen by a tumor's molecular profile (including the same mismatch-repair and p53 status used for immunotherapy decisions), against standard radiation, for women with higher-risk early endometrial cancer after surgery.

What they found

• Molecular-profile-guided treatment was as safe as standard radiation.
• Many women were safely able to have less treatment than they would have under the old staging system.

What it means

Points toward replacing one-size-fits-all radiation with treatment matched to each tumor's biology.