Evaluation of size in prognosis of oral cancer.

Greatest surface diameter of a cancer, together with suspicion of regional node metastasis, forms the basis for prognosis through the clinical TNM staging system for many cancers. In oral cancer, however, surface size sometimes fails to correlate, or sometimes inversely correlates, with tumor aggressiveness. To shed light on the value of measuring size per se, 155 consecutive oral squamous cancers, treated by surgery, radiation, or a combination, were analyzed to find the degree of correlation between greatest surface measurement and pathologic nodal spread and control of cancer. In tumors less than 2 cm, size correlated with very few nodal metastases and with good prognoses; in tumors greater than 2 cm, increasing size did not show a corresponding increase in pathologic node metastasis or significantly worsening outcomes except for a few very large cancers invading adjacent structures. In conclusion, greatest surface diameter of an oral cancer, when greater than 2 cm, is an unreliable predictor of tumor behavior per se. A small pilot study suggests that tumor thickness may be a better predictor. A formal study of this is planned.