Multidisciplinary Management of Retinoblastoma: Approach to Treatment.

Treatment Modalities for Retinoblastoma - Intraarterial, Systemic and Intravitreal Chemotherapy

Dr. Ramasubramanian: For retinoblastoma, the wide range of treatment options available include local treatment, laser and cryotherapy, which is mainly reserved for very small tumors or as an adjunct to systemic chemotherapy or intraarterial chemotherapy. When there's a small reoccurrence, that's when you use local treatment. The next is intraarterial chemotherapy, where we go up the femoral artery, go up to the ophthalmic artery and give chemo only to the ophthalmic artery. The systemic toxicity is minimal, but there's a very hard dose given to the eye. This is predominantly used for group B, group C and group D retinoblastoma that is localized to one eye, or after you've given systemic chemotherapy if there is recurrence, then we use the intraarterial chemotherapy. Intraarterial chemotherapy is done by our interventional radiologist.

Systemic chemotherapy. We use it mainly for kids who have tumors in both eyes. We like to start off with systemic chemotherapy. Our pediatric oncologist is the one who primarily delivers the systemic chemo. The last kind of chemo is the intravitreal chemo where we actually inject chemotherapy directly into the eye, and this is done for persistent or recurrent vitreous seeds. The vitreous is avascular, so whether you give chemo intraarterially or systemically, it really doesn't reach a sufficient dosage in the vitreous. So these have to be treated with intravitreal chemo. This is usually done by the ocular oncologist at Phoenix Children's, it's done by me, where we give chemotherapy directly into the eye under anesthesia.

Treatment Modalities for Retinoblastoma - Radiotherapy

Regarding radiation treatment, we have kind of moved away from radiation treatment for retinoblastoma, mainly because of the risk of second cancers. These kids are radiosensitive, and there is close to 25% chance of second cancers in germline retinoblastoma, so we try to avoid external beam radiation. In rare scenarios, we would do plaque brachytherapy when we want local control that we have not achieved with systemic chemo or intraarterial chemo. Again, the radiation plaque is custom made for the tumor and for the eye. The surgery itself is done by the ocular oncologist, but the radiation plaque is made by the radiation oncologist.

Treatment Modalities for Retinoblastoma - Surgery

The last treatment is enucleation, and that's usually reserved for group E retinoblastoma, where there's a very advanced retinoblastoma with high pressures, or if there's imminent extraocular extension, or if all our other treatment modalities have failed, then we proceed with enucleation.

Treatment Modalities for Retinoblastoma - Adjuvant Therapy

In retinoblastoma, often times it [is] adjuvant. We always do the systemic chemotherapy and intraarterial chemotherapy along with our local therapy of laser and cryotherapy, so it's almost always adjuvant. When it comes to systemic chemotherapy, we usually do six cycles of the vincristine, etoposide, carboplatin, and 24 to 48 hours prior to delivery of systemic chemotherapy we actually do local laser and cryo. It has two advantages. One, the laser cryo by itself can shrink the tumor. The other advantage is that it breaks the blood retinal barrier so actually more chemo penetrates into the eye. Almost all our treatments are adjuvant treatments.

PracticeUpdate: As a practical matter how does the team work together in these scenarios where you need systemic chemotherapy, and obviously the ophthalmologist is involved? Can you walk us through how you do things at your center?

Dr. Ramasubramanian: At our center, we actually have weekly tumor boards where we discuss all our kids, and thanks to Zoom everything is very easily coordinated now. We have a weekly tumor board where we discuss all our patients and how to go about it. When it comes to intraarterial chemotherapies, how we actually do it is we try to minimize the number of anesthesias for our kids, so it's always coordinated care. Usually I will do my exams under anesthesia and they'll follow and get that intraarterial chemotherapy at the same time. Be it for MRI, be it for any other treatments, oftentimes these kids need audio screenings, so we try to coordinate care so kids are not going under anesthesia so many times.