Melanoma staging and survival

melanoma skin cancer ---> melanoma survival


A great deal of information is available regarding various factors that correlate with the clinical outcome of patients with melanoma. Some of these prognostic factors, such as microstaging and nodal status, are of sufficient independent significance to be incorporated into staging systems with known survival rates. Other prognostic factors, such as tumor ulceration and microscopic versus macroscopic nodal disease, have also been found to be significant variables that influence survival and have been incorporated into the staging system.

One of the most important prognostic features of cutaneous melanoma is the stage of development of the primary tumor. The microstaging method that is used routinely was originally described by Breslow. This method classifies the primary tumor according to its thickness in millimeters, as measured with an ocular micrometer, from the top of the granular layer to the base of the tumor. Many investigators have documented an inverse correlation between tumor thickness and survival. The ulceration status and mitotic rate are also independent factors that are used to determine microstaging of the primary lesion. Prior to the use of the Breslow microstaging method, melanomas were staged according to the level of invasion into the histologic layer of skin. This was known as Clark's level of invasion and comprised five levels (I = in situ lesions, V = subcutaneous involvement). Several studies have confirmed that Breslow thickness conveys more accurate prognostic information than does the determination of Clark level.
The presence of regional lymph node metastases is associated with a worsening prognosis. The tumor burden (microscopic versus macroscopic disease) of involved lymph nodes has an inverse correlation with long-term survival. The 5-year survival rate for patients with involved lymph nodes ranges from 70% to 25%, based primarily on tumor burden and ulceration status of the primary lesion). The use of sentinel lymph node biopsy (SLNB) has identified a subgroup of patients with micrometastatic nodal disease who have a favorable prognosis compared with patients with macroscopic nodal involvement. This information has been incorporated in the staging system as well.

The American Joint Committee on Cancer (AJCC) developed a five-stage system that divides melanomas according to tumor thickness (T), nodal status (N), and metastatic disease (M). There are five stages based on prognosis: stage 0 (in situ melanoma), stage I (local disease), stage II (local disease), stage III (regional nodal, in-transit, or satellite metastases), and stage IV (distant metastases). In general, increasing stage is associated with decreasing survival.

The major prognostic factors that predict survival in melanoma patients have been accounted for in the AJCC staging system: namely, tumor microstaging, ulceration, nodal status, and distant metastases.The presence of ulceration in a melanoma appears to be associated with a poorer prognosis. Men have a higher proportion of ulcerated lesions than women (27% vs. 19%, respectively). Although ulceration appears to correlate with thickness of the melanoma, the presence of ulceration has been shown to be an independent prognostic factor and has been included in the staging system. Additionally, a higher mitotic rate of 1.0 mm2 or greater has been shown to be an independent prognostic factor in one large study.