Stage IB includes: (T2, N0, M0, G1 or GX); (T3, N0, M0, G1 or GX). T2: Tumor measuring more than 8 cm in greatest dimension. T3: Discontinuous tumors in the primary bone site. N0: No regional lymph node metastasis. M0: No distant metastasis. GX: Grade cannot be assessed. G1: Well differentiated, low grade. (AJCC 8th ed.) [from NCI]