Intra-arterial Chemotherapy
Introduction of chemotherapy dramatically changed the treatment and outcome of patients affected with retinoblastoma. Potential systemic risks have stimulated the need to develop more focal chemotherapy delivery techniques. Intra-arterial chemotherapy is a promising new technique for retinoblastoma management with selective delivery of chemotherapy to the eye with minimal systemic side effects. Currently this treatment is employed in retinoblastoma patients as primary treatment for unilateral or bilateral retinoblastoma and as secondary treatment following failure from other treatments.
Under general anesthesia the site of cannulation in the femoral artery (artery in the leg) is prepped in a sterile fashion and an appropriate size arterial sheath is placed. An arteriogram is then performed to visualize the cerebral vasculature and to select the best approach showing the takeoff of the ophthalmic artery (artery going to the eye)(Figure 1A). Using fluoroscopic guidance the catheter is then advanced into the ophthalmic artery (Figure 1B). Once the catheter positioning is confirmed, chemotherapy is delivered. The currently used drugs are melphalan and carboplatin. The entire procedure (including time of injection of chemotherapy) takes 2-5 hours depending on the vascular anatomy of the patient. Figure 2A and 2C show the tumor and the ultrasound appearance before treatment in a child with retinoblastoma. The remarkable response following intra-arterial chemotherapy is demonstrated in figure 2B and 2D.
Advantages of Intra-arterial chemotherapy
This technique allows selective delivery of chemotherapy to the eye with minimal systemic absorption. No side effects of chemotherapy like fever, vomiting, loss of scalp hair, or infection have been witnessed so far. The dose delivered to the eye is 10 times that achieved with systemic chemotherapy. This high dose of chemotherapy delivered to the eye accelerates regression of tumor and seeds.
Drawbacks of Intra-arterial chemotherapy
There are many considerations when deciding on intra-arterial chemotherapy. In 3-5% of patients the ophthalmic artery is anomalous and in these instances the procedure has to be abandoned. The chemotherapy infusion has to be repeated every 3-4 weeks for up to 3-6 injections for complete regression of tumor. The cannulation of ophthalmic artery is difficult in children particularly in infants less than 6 months and requires surgical expertise and precision. As it is a invasive procedure the risk of neurological complications have to be considered though they are rare. Most patients experience self-limiting swelling of the eye and the lids which persists for 1-2 weeks following chemotherapy. Others have had bleeding into the eye.