This article originally appeared on DIPG.org
The Cure Starts Now sat down with Dr. Luke Pater, Associate Professor of Radiation Oncology at the University of Cincinnati Department of Radiation Oncology and Cincinnati Children’s Hospital, to discuss re-irradiation in terms of DIPG, DMG and medulloblastoma.
Recently families facing progression of DIPG, DMG and Medulloblastoma have received recommendations to consider re-irradiation, can you explain what this involves?
Re-irradiation for brain tumors is very similar to the initial experience for patients. It involves the same planning process with CT simulation and subsequent daily radiotherapy. The difference lies primarily in the dose considerations given that the brain never fully recovers from the initial treatment. This makes further radiotherapy typically of a higher risk than the first course.
Is this something new or is it being recommended because of some evidence of efficacy?
Re-irradiation is not new; however, it is currently being applied more often. This is largely due to an increase in experience and data showing safety. Multiple publications have come out related to DIPG, DMG and medulloblastoma tumors as well as other intracranial tumors showing that with appropriate precautions, reirradiation can be safely delivered with acceptable risks.
The benefits are variable pending multiple clinical factors such as the specific tumor type, time from initial treatment and adjuvant chemotherapy/immunotherapy/target therapy options.
What should families and patients know about re-irradiation, including side effects?
Re-irradiation poses the same risks as would have been discussed at initial course of treatment. This is due to the fact that the same central nervous system tissues will be exposed to radiation. If there is a change in the intracranial site treated, then the particular risks could change. For example, lesions located near the optic apparatus will have risks of radiation induced vision changes and those near the motor cortex may pose a risk of weakness if the patient develops damaged tissue from the exposure.
Is there a particular type of radiation to consider?
Similar to the upfront setting, the vast majority of radiotherapy for brain tumors is administered externally, meaning from a machine or material producing radiation which is then directed into the patient. Photon and proton radiotherapy are the two most common forms of radiotherapy delivered in this fashion. Tumor location, patient prognosis, possibility of adjuvant therapies, prior radiation treatment and its dose to critical areas, time frame needed to initiate treatment as well as socioeconomic factors, such as ability to get to a particular center for the duration of treatment, all play a role in selection of the best type of radiotherapy for an individual patient.
Do some procedures involve combinational therapies?
Many retreatment patients are either continuing on, or initiating a new therapy in addition to radiation. This may also be in the context of a clinical trial. Some agents require a break wither before, during or after radiation due to risks of synergistic mechanisms causing an increase in toxicity.
Anything else you can tell us about re-irradiation?
Clinicians, like patients and their families, are saddened that they have to consider another course of radiation. It is their hope that all patients are tumor free with their upfront treatment. However, clinicians recognize that some of these malignancies recur. Re-irradiation is not always a safe or appropriate consideration, yet they are pleased to offer it when needed and deemed safe. Clinicians continue to refine the optimal doses and techniques to recommend, for example with an active institutional trial for cases DMG that are currently ongoing.