Fluorescent in situ hybridization evaluation of p53 gene deletions at a tumor interface of lingual carcinoma

Abstract

Objective/Hypothesis: To evaluate the ability of fluorescent in situ hybridization (FISH) to detect malignant cells missed by standard histological assessment at an interface between malignant and normal tissue in lingual squamous cell carcinoma (SCC) and to correlate findings of FISH assessment with patients' clinical stages. Study Design: Retrospective assessment of archival tissue from 31 patients with lingual SCC treated at University of Wisconsin Hospital and Clinics in Madison. Methods: An assay combining standard histological and FISH techniques was used to assess a tumor interface tissue section and allow identification of each tumor's ploidy characteristics and p53 gene deletions and the presence or absence of malignant cells within tissue viewed as 'normal' on histological review. Results: Forty-five percent of tumors (14 of 31) demonstrated ploidy changes and 84% (26 of 31) showed p53 deletions. Of these 26 tumors with p53 deletions, 14 were found to have 'microfoci' with p53 deletions within tissue that appeared normal on histological examination. These microfoci were found in 75% of late-stage tumors and in only 35% of early-stage tumors. Conclusions: FISH allowed identification of malignant cells in tissue viewed as normal on standard histological assessment, and this finding occurred more frequently in late-stage tumors.