According to the American Joint Committee on Cancer (AJCC), the natural course of MCC is “variable and depends heavily on the stage at diagnosis". Staging of MCC is classified according to the TNM staging system, a notation system that describes the stage of cancer according to the size of the primary tumor (T), the degree of spread to regional lymph nodes (N), and the presence of distant metastasis (M). A combination of T, N, and M stages dictate the final clinical stage group (0, I, IIA, IIB, IIIA, IIIB, IV). Advanced stage (i.e. increased size of the tumor, spreading of the tumor into surrounding and/or distant tissue, and involvement of lymph nodes) is associated with lower survival rates.