Comparison of uterine vs nonuterine leiomyosarcoma showed the following: Uterine tumour samples (n=46) were positive for CDK4, CDK6, and p-Rb in 65.2%, 87.2%, and 73.9%, respectively; 30.4% expressed ≤10% p16 protein. The gene discussed is RB1; the disease is neoplasm.