Stage II malignant melanoma: presentation of a prognostic model and an assessment of specific active immunotherapy in 1,273 patients.

The ability to redefine risk factors and to predict prognosis in patients with malignant melanoma at the time they manifest nodal metastasis can be a benefit to the patient emotionally and to the physician therapeutically. A retrospective review of 1,273 patients with stage II malignant melanoma was performed at our institution. The most significant prognostic factors in a simultaneous hazard Cox multivariate analysis, predicting melanoma-related mortality among stage II patients, were the number of positive nodes (P less than 0.0001), age (P = 0.0004), site of the primary lesion (P = 0.0036), disease-free interval (P = 0.016), thickness of the primary lesion (P = 0.017), and sex of the patient (P = 0.0616). We have developed a model for predicting survival of stage II patients, designed for use in the clinic setting. Its application in a computer system makes it accessible and understandable. The most favorable risk group (18% of the population) has actuarial 5- and 10-year survival rates of 58% and 49%, respectively, from the time of the nodal metastasis. The least favorable risk group (7% of the population) has 5- and 10-year survival rates of 15% and 10%, respectively. There are three intermediate risk groups. All groups differ prognostically (P less than 0.04). The principal adjuvant therapy offered to these patients was specific active immunotherapy, which appears to have a 10-20% survival benefit in stage II patients with greater than one positive node, when compared with institutional controls. The apparent survival benefit of the immunotherapy supports continued clinical investigation of its therapeutic potential.