Target volume dose and clinical outcome in radiotherapy for primary marginal zone lymphoma of the ocular adnexa

The aim of the present study was to determine the optimal dose and optimal target volume for marginal zone lymphoma of the ocular adnexa. Between January, 2008 and December, 2013, 40 patients with histologically proven primary marginal zone lymphoma of the ocular adnexa who underwent radiotherapy at the Tokyo Medical University were evaluated. The prescribed dose was 30 Gy in 15 fractions to the iso-center. Doses to the gross tumor volume (GTV), conjunctiva, bulbus oculi, retina and retrobulbar space were investigated, and the association between dose-volume factors and clinical outcome was analyzed. The overall and local progression-free survival rates at 3 and 5 years were 100% during a median observation period of 32 months. Two patients relapsed in the contralateral ocular adnexa. The progression-free survival rates at 3 and 5 years were 100 and 93.3%, respectively. The mean dose was 2.0 and 1.9 Gy for targets receiving 95% of the GTV dose (D95). The minimum dose was 0.9–2.0 Gy (median, 1.8 Gy). Thus, primary marginal zone lymphoma of the ocular adnexa favorably responded to lower doses of radiation, compared with prescribed doses to the iso-center. A radiation dose of 27 Gy in 15 fractions at D95 of GTV appeared to be optimal.