Nomograms and Staging in Melanoma: New Tools for Better Predicting Outcomes

Predicting outcomes for patients diagnosed with primary melanoma, as with any cancer, has several important utilities, including patient counseling, therapeutic decision making, designing and interpreting clinical trials, and optimizing health outcome assessments. Melanoma, more so than many other cancers, has lent itself to the development of predictive models initially based on microstaging methods, such as tumor depth using Breslow thickness and Clark level of invasion, and, more recently, to detecting micrometastases with the sentinel lymph node biopsy technique. In addition, a number of other factors have been associated with varying degrees of prognostic significance that reflect either patient-related factors (such as age, sex, site, or lymphatic drainage pattern) or tumor-related factors (such as ulceration, regression, vertical growth phase, mitotic rate, lymphovascular invasion, tumor-infiltrating lymphocytes, satellitosis, or perineural invasion). What has proven quite challenging, however, has been how to develop a useful staging system that tries to incorporate these multiple factors in a fashion that uses reliable and independent predictors of survival outcome and accurate prognostic modeling in the least invasive way possible. In 2002, the American Joint Committee on Cancer (AJCC) completely revised its staging system for melanoma to more accurately incorporate independent prognostic factors based on a multivariate analysis. This staging system evaluated an array of prognostic factors and ultimately incorporated tumor-node-metastasis and stage grouping criteria that included tumor thickness, level of invasion, ulceration, nodal status, and distant disease status. The staging system was additionally validated by using a newly created 13-institution database called the AJCC Melanoma Staging Database, which contained prospectively collected data on 17,600 patients. There has been uniform agreement that the new staging system is a marked improvement over the old staging system with regard to its clinical utility. However, there are some concerns that the new staging system, especially with regard to thin melanomas less than 1 mm in depth, may have some limitations in discriminating recurrence and survival differences within the T1N0M0 subgroup. Although one of the important aspects of a staging system is certainly to allow grouping of patients to allow a global assessment of interventions on homogeneous groups of patients, another evolving consideration is the ability to provide an individual patient with specific prognostic information. As the number of independent predictive factors identified increases, future staging systems will need to be flexible enough to allow for incorporation of these various factors and a method for validating them. In this issue of Annals of Surgical Oncology, Wong et al. have constructed a predictive model of sentinel lymph node positivity. Using the Memorial SloanKettering Cancer Center melanoma database, they have constructed a nomogram for melanoma that is based on age, site, thickness, level, and ulceration and that is relatively easy to use; it has an ability to predict the probability of a positive sentinel lymph node. The nomogram was compared with AJCC staging for accuracy in predicting micrometastases in a sentinel Received January 28, 2005; accepted February 14, 2005; published online March 14, 2005. Address correspondence and reprint requests to: Douglas S. Tyler, MD; E-mail: tyler002@acpub.duke.edu