A Multifactorial Analysis of Melanoma

Abstract

Twelve prognostic features of melanoma were examined in a series of 185 patients with nodal metastases (Stage II), who underwent surgical treatment at our institution during the past 20 years. Forty-four per cent of the patients presented with synchronous nodal metastases (substage IIA), 44% of the patients had delayed nodal metastases (substage IIB), and 12% of the patients had nodal metastases from an unknown primary site (substage IIC). The patients with IIB (delayed) metastases had a better overall survival rate than patients with IIA (synchronous) metastases, when calculated from the time of diagnosis. These differences could be explained on the basis of tumor burden at the time of initial diagnosis (microscopic for IIB patients versus macroscopic for IIA patients). Once nodal metastases became evident in IIB patients, their survival rates were the same as for substage IIA patients, when calculated from the onset of nodal metastases. The survival rates for both subgroups was 28% at five years and 15% for ten years. Substage IIC patients (unknown 1 degrees site) had better five-year survival rates (39%), but the sample size was small and the differences were not statistically significant. A multifactorial analysis was used to identify the dominant prognostic variables from among 12 clinical and pathologic parameters. Only two factors were found to independently influence survival rates: 1) the number of metastatic nodes (p = 0.005), and the presence or absence of ulceration (p = 0.0019). Additional factors considered that had either indirect or no influence on survival rates (p > 0.10) were: anatomic location, age, sex, remission duration, substage of disease, tumor thickness, level of invasion, pigmentation, and lymphocyte infiltration. All combinations of nodal metastases were analyzed from survival differences. The combination that showed the greatest differences was one versus two to four versus more than four nodes. Their five-year survival rates were 58%, 27% and 10%, respectively (p < 0.001). Ulceration of the primary cutaneous melanoma was associated with a <15% five-year survival rate, while nonulcerative melanomas had a 30% five-year survival rate (p < 0.001). The combination of ulceration and multiple metastatic nodes had a profound adverse effect on survival rates. While tumor thickness was the most important factor in predicting the risk of nodal metastases in Stage I patients (p < 10(-8)), it had no predictive value on the patient's clinical course once nodal metastases had occurred (p = 0.507). The number of metastatic nodes and the presence of ulceration are important factors to account for when comparing surgical results, and when analyzing the efficacy of adjunctive systemic treatments.