Prognostic significance of DNA ploidy in oral squamous cell carcinomas. A retrospective flow and image cytometric study with comparison of DNA ploidy in excisional biopsy specimens and resection specimens, primary, tumors, and lymph node metastases

Abstract

Deoxyribonucleic acid ploidy was determined in paraffin-embedded tumor tissue from 116 patients with primary oral squamous cell carcinomas (including 5 carcinomas of the lip and 14 of the tongue) by means of flow cytometry. One hundred six cases were suitable for evaluation (91%). Sixty-eight percent of the cases (n = 72) showed a nondiploid nuclear DNA content. Nondiploidy correlated significantly with presence of lymph node metastases (p < 0.02) but not with tumor stage, grading (World Health Organization), or relapse-free and overall survival. Carcinomas of the lip and tongue turned out to be diploid more frequently than other oral squamous cell carcinomas (p = 0.002). In the 21 cases in which a comparison of DNA content of excisional biopsy specimens and subsequent resection specimens was possible a difference in DNA ploidy was found in one case only. The comparison of primary tumors and their lymph node metastases in 30 cases revealed a discrepancy of DNA content in five cases (17%), which was connected with a shift from nondiploidy to diploidy in four out of five cases. Fifty cases studied in parallel by means of image cytometry with Feulgen-stained tissue sections exhibited a concordance of the ploidy status in 87% and a significant correlation of the DNA index values obtained with both methods (p < 0.01). These results demonstrate that DNA ploidy in oral squamous cell carcinomas is distributed rather homogeneously within the tumors and remains rather stable in the lymph node metastases. Despite a significant correlation between nondiploidy and presence of lymph node metastases, ploidy failed to be a statistically significant parameter for prognosis in oral squamous cell carcinomas in our investigation.