This initiative seeks to enhance our mechanistic and epidemiologic understanding of infection-related cancers, with a focus on the etiologic roles of co-infection in cancer.Preference will be given to co-infections (excluding co-infection with human immunodeficiency virus [HIV]) that engendered novel opportunities for prevention and treatment and focus on understudied populations. Coinfection is defined as the occurrence of infections by two or more infectious (pathogenic or nonpathogenic) agents either concurrently or sequentially and includes both acute and chronic infections by viruses, bacteria, parasites, and/or other microorganisms.