A combination of two topical drugs that have been in use for years triggers a robust immune response against precancerous skin lesions, according to a new study. The research, from Washington University School of Medicine in St. Louis and Harvard Medical School, shows that the therapy activates the immune systemโ€™s T cells, which then attack the abnormal skin cells.

The study, which involved patients with actinic keratosis, a precursor to a type of skin cancer called squamous cell carcinoma, is published Nov. 21 in The Journal of Clinical Investigation.

โ€œWe looked at precancerous lesions on patients with sun-damaged skin,โ€ said Washington University dermatologist and study co-author Lynn A. Cornelius, MD, director of the Division of Dermatology. โ€œMost commonly found on the face, scalp and arms, these lesions appear abnormal by visual examination and under the microscope but are not full-blown skin cancers. But because these lesions have the potential to develop into a true skin cancer, they are commonly treated. Our study shows this combination therapy is more effective and better tolerated than current treatment practices.โ€