The objective of this study was to report the case of a patient who developed six oral cavity tumors in five years of treatment and, also, demonstrate the immunohistochemical changes for p53 and Ki-67, routinely used to assess dysplasic regions.<h4>Case report</h4>When altered, p53 and Ki-67 suggest the presence of field cancers, an area with genetically altered cells, presenting a high risk of developing premalignant and malignant lesions. The gene discussed is MKI67; the disease is cancer.