Cutaneous malignant melanoma. II. The natural history and prognostic factors influencing the development of stage II disease.

The survival history of 259 patients with Stage I cutaneous malignant melanoma who were at risk for developing regional nodal metastases (Stage II) were studied. Eighty-seven of 377 Stage I patients (23%) developed regional nodal metastases (Stage IIB) with 40% 5-year survival. Fifty patients had regional nodal metastases at presentation, with or without a known primary (Stages IIA or IIC, respectively), with a 42% 5-year survival. A step-down multivariate analysis using the Cox regression model revealed four risk factors as being highly significant for predicting a more favorable survival outcome: (1) thinner Breslow thickness (P = 0.0001), (2) pathologic Stage I disease (P = 0.004), (3) no clinical ulceration (P = 0.0004), and (4) being a woman younger than 50 years of age (P = 0.029). These results are discussed in reference to other series.