Candida albicans as a promoter of oral mucosal neoplasia.

A model of oral mucosal carcinogenesis using the water-soluble carcinogen 4-nitroquinoline-1-oxide (4NQO) was combined with a model of oral mucosal candidosis to examine the ability of Candida albicans to promote the development of neoplasia in suitably initiated epithelium. Sprague-Dawley rats were initiated by the application of 4NQO to their palatal and tongue mucosa 3 times weekly for 4 weeks. The animals then received either application of a phorbol ester to act as a promoter, induction of experimental oral mucosal infection with C. albicans, or no further procedures. Animals were killed at 34 or 52 weeks and the tongues and palates sectioned for light-microscopic examination. Control groups with no treatment, mucosal infection only, phorbol ester application only, 4NQO with the tetracycline or vehicle application only were also used. The development of carcinoma in the experimental groups was similar to that in the positive control groups, indicating that the particular strain of Candida used had a similar ability to promote neoplastic changes as the known promoter phorbol-12,13-didecanoate and caused neoplastic changes to occur by week 34 with no additional lesions occurring by week 52. This indicated that the speculation that strains of C. albicans may participate in causing neoplastic transformation in humans was well founded.