PREDICTING LYMPH-NODE METASTASES IN RECTAL-CANCER

For properly selected rectal cancers, local excision is a sphincter-sa ving alternative to abdominoperineal resection. If histologic assessme nt of a locally excised tumor reveals ominous features, further treatm ent with radical resection or irradiation may be necessary to treat po tential lymph node metastases. PURPOSE: We wished to determine which f eatures, if any, were predictors of nodal metastases. METHODS: Nine hi stologic and morphologic features of 62 radically excised rectal cance rs were reviewed to determine which factors, if any, were associated w ith nodal disease. RESULTS: Using a chi-squared analysis, we found wor sening differentiation (P 0.0001), increasing depth of penetration (P = 0.026), a microtubular configuration of 20 percent or more (P = 0.02 3), and the presence of venous (P = 0.001) or perineural invasion (P = 0.002) to significantly influence nodal disease. Lymphatic invasion w as witnessed too infrequently to determine significance but, when pres ent, was associated with nodal metastases in every case. Exophytic tum or morphology, mitotic count, and tumor size were not significant pred ictors. An analysis of variables determined that, of all factors or co mbination of factors examined, Broder's classification was the stronge st predictor of nodal disease. CONCLUSIONS: If a rectal cancer is acce ssible and of small size to facilitate local excision, an in-depth his tologic assessment is needed to determine if nodal metastases are like ly on a statistical basis.