NF1 and neoplasm: In univariate Cox analysis, large tumor size (P = 0.034), deep tumor location (P = 0.002), MIB-1 positivity (P = 0.003), AJCC stage, and HIF-1α positivity (P = 0.038) were significantly associated with poor prognosis; however, prognosis was not significantly associated with NF1 status, MVD, age, sex, tumor location, HIF-2α positivity, or tumor necrosis (Table 3).