The AJCC prognostic criteria are the traditional standard for staging cutaneous melanoma (Balch, CM, et. al., Melanoma of the Skin, 2009). However, histopathologic techniques alone do not optimally identify patients at high risk for metastasis. For instance, while Stage I melanomas are considered low risk as a group, some patients do metastasize and are at high risk for metastasis (Balch, 2009).
There is also poor accuracy for predicting those Stage II patients at high risk for metastasis. Under the current staging system, the 5-year survival rate for clinical Stage II subjects is 53-82%, which overlaps significantly with the survival rate of 22-68% for Stage III cases (Balch, CM, et. al., 2009, 2010). In fact, Stage IIB and IIC patients have a worse 5-year survival rate than stage IIIA patients. These data indicate that there are a significant number of Stage II patients that are not accurately diagnosed as high risk using the current prognostic tools.
Sentinel lymph node status has been reported as the most accurate prognostic factor for metastatic activity and survival (Gershenwald, JE, et. al., 1999; Morton, DL, et. al., 2006). However, of the 60,000 patients diagnosed with Stage I or II disease last year, up to 8,500 will develop distant metastatic disease within five years of diagnosis (Kalady, MF, et. al., 2003).
The potential impact on clinical management for Stage I or II melanoma is significant given that the 5-year metastasis risk for DecisionDx-Melanoma™ Class 2 melanoma is greater than that of AJCC Stage III melanoma. For example, Class 2 patients may benefit from referral to a surgeon or oncologist for consideration of higher intensity monitoring, repeat lymph node mapping, lymph node dissection, adjuvant treatment and clinical trials.
Also, while it is not often the urgent focus of oncology management discussions, the impact of the relatively good news of receiving a Class 1, low-risk designation should not be underestimated.