THE PROGNOSTIC VALUE OF INDIVIDUAL HISTOLOGIC GRADING PARAMETERS IN SMALL LINGUAL SQUAMOUS-CELL CARCINOMAS - THE IMPORTANCE OF THE PATTERN OF INVASION

Background. The histologic grading of the deep invasive margin of oral squamous cell carcinoma recently has been shown to have prognostic va lue, but previous series have not been homogeneous enough to allow gra ding parameters to be assessed individually. Methods. Forty-seven smal l lingual carcinomas limited to the lateral border of the tongue and t reated by radiotherapy were graded histologically at their deep invasi ve front. Clinical and grading parameters were correlated by statistic al tests performed by permutational techniques. Results. Carcinoma rec urred locally in 6 patients, and metastases developed in 19. Local rec urrence correlated with Broders' grade (P = 0.0143), keratinization (P = 0.017) and pattern of invasion (P = 0.0195). Metastasis had a highl y significant correlation with Broders' grade (P < 0.001), pattern of invasion (P < 0.001), and invasive front grading total score (P < 0.00 1). Seven of 8 carcinomas with diffuse infiltrating patterns metastasi sed, whereas only 4 of 25 with large islands or a broad infiltrating p attern metastasized. Conclusions. The usefulness of the deep invasive front grading system for small lingual carcinoma was demonstrated. The pattern of invasion was the component of the grading system that had the closest correlation with metastasis and recurrence in this type of carcinoma.