American Association for Cancer Research Apr 21 2026 Injecting nivolumab (Opdivo) directly into precancerous oral lesions led to reduction in lesion size and allowed some patients to avoid surgery, according to research from a phase I clinical trial presented at the American Association for Cancer Research (AACR) Annual Meeting 2026, held April 17-22. Approximately 5% of the general population have precancerous lesions in their mouth that can carry a 1% to 36% risk of progression to oral cancer,