Prediction of malignant melanoma recurrence by serum N-acetylneuraminic acid.

Since serum N-acetylneuraminic acid (NANA) can serve as a relatively sensitive monitor of tumor burden, we wished to examine the relationship of NANA to other suggested prognostic factors for malignant melanoma. Eligible patients included 151 patients with stage-I disease and 10 with stage-II regional lymphatic extension. A proportional hazards model was used to examine nine factors, of which five were not significant predictors of recurrence: age, sex, primary site, tumor diameter, and stage. Significant predictors included: measured depth p = 7 X 10(-7); anatomic depth (Clark level), p = 7 X 10(-6); NANA, p = 0.003; and growth pattern (superficial spreading vs nodular), p = 0.01. However, on multivariate analysis only two predictors were independent; measured depth and NANA. The latter could not be explained by non-specific factors. The data were examined to define optimal test values for assignment of risk. According to this model, patients with lesions greater than 1.75 mm and NANA less than 2 mumol/ml have a more than 12-fold greater risk of recurrence by 2 years than those with lesions less than or equal to 1.75 mm and NANA less than or equal to 2 mumol/ml.