Phase II prospective multicenter study for stage I/II Follicular Lymphoma treated with involved-field radiotherapy (IFRT) at doses of 24 Gy) with or without Ofatumumab for 8 weekly doses on molecular basis. Patients with positive basal Bcl-2 will be followed every 3 months and with Bcl-2 detection every 6 months for 3 years. Patient with negative basal Bcl-2 will be followed every 3 months without further Bcl-2 detection.