Defining Vitreoretinal Lymphoma
The goal of ocular treatment is to avoid systemic toxicity while inducing intraocular CR and improving vision. It has not yet been proved whether achieving local CR will reduce the risk of CNS relapse.
MTX vitreous injections
Administration of MTX vitreous injection has achieved complete remission in 95% of the 44 eyes in 26 cases. MTX vitreous injection （400μg/0.1mL）has been administered twice a week for 1 month, once a week for 1 month, and once a month for 9 months. It is reported that complete remission was achieved after an average of 6.4 injections (2-16 injections; 95% of the cases with less than 13 injections), and most achieved complete remission after 10 injections. However, the same report stated that while all 26 patients achieved complete remission with no relapse in the ocular lesion, 14 of the cases (54%) progressed to CNS and systemic relapse. With poor prognosis, median overall survival was 17 months (3-84 months) (Br J Ophthalmol. 2008;92:383-8). Thus, MTX vitreous injections are highly effective against ocular lesions, but inadequate in inhibiting the progression of CNS relapse.
Ocular radiotherapy has achieved a complete remission rate (87%) with ocular radio-beam (35-40Gy) against primary VRL. However, 2-years progression-free survival rate was approximately 50%. While external-beam ORT (30-40 Gy) is an alternative ocular treatment, it is rarely used as the sole first-line treatment. Lower doses of ORT (<30 Gy) reduced the risk of cataracts and radiation retinopathy.
Several clinical trials have been conducted to prevent the tumor’s microinvasion into the CNS. In Europe and the US, treatments incorporating ocular radiotherapy and chemotherapy were trialed. However, 53% of the patients underwent CNS relapse. We executed a treatment protocol combining MTX vitreous injection, systemic chemotherapy, and preventive low-dose whole-brain radiation therapy. The treatment reported that the VRL 4-year progression-free survival rate greatly improved to 72.7%, and the CNS relapse improved to 10%. However, the study reported that a certain number of patients will relapse, with the treatment reporting a 27.3% relapse rate within 4 years. The study also observed that 75% of elderly patients undergoing intense chemotherapy faced complications such as grade 2 or higher Leukoencephalopathy, resulting in cognitive decline. Due to these critical clinical issues, alternative treatments are desired.