Dr. Christine Hill-Kayser, associate professor of radiation oncology at the University of Pennsylvania and the Children’s Hospital of Philadelphia, reviewed two abstracts given at ASCO by Dr. Florence Wong and Dr. James Bates concerning the late effects of radiation. Later on, Dr. Hill-Kayser presents ways to reduce radiation exposure during treatment.
The first abstract Dr. Hill-Kaser discussed was presented by Dr. Florence Wong with the Childhood Cancer Survivor Study using female survivors who had received 10 gray or more chest radiation for Hodgkin lymphoma. Research shows that a female child receiving 10 gray or more radiation to the chest resulted in a 40% increase in developing breast cancer. Breast cancer in neuroblastoma survivors is rare; however, it does happen.
When spinal radiation is given to either in the setting of craniospinal radiation for a brain tumor or the treatment of neuroblastoma, the dose to the spine might range from 21.6 to 55.8 gray.
B. Dr. James Bates studied the impact of radiation to the chest of a large number of survivors utilizing the Childhood Cancer Survivor Study. The median follow-up of their population approached 30 years, of 12,000 survivors. They also compared this group to a non-radiation group.
Overall, the group found that coronary artery disease, heart failure, and valvular disease were relatively low within this population. However, they did note that radiation dose of five to 10 gray to the heart was associated with an increased relative risk of cardiac toxicity, including congestive heart failure, myocardial infarction, pericardial disease, and valvular disease. In pediatrics, the heart and breast are almost never radiation targets. They receive radiation because they are in close proximity to other structures that need radiation, like lung tissue or the spine. The radiation scatter of conventional radiation therapy is the problem.
When giving spinal radiation either in the setting of craniospinal radiation for a brain tumor or in the setting of treatment of a paraspinal sarcoma or neuroblastoma, dose to the spine might range from 21.6 to 55.8 gray, definitely higher than 10 gray. And the dose to cardiac structures is really variable in this setting. When you think about these two studies, Dr. Bates’s group found that the dose to cardiac structures is significant at doses of five gray or higher, and Dr. Wong and her group found that the lifetime breast cancer risk incidence is really quite high in patients who’ve had 10 gray to the chest or more.
Over the past decade, there has been a significant effort to minimize radiation dose to chest structures in young people, which has resulted in increased use of two new approaches – intensity-modulated radiotherapy (IMRT) and proton therapy. IMRT uses multiple beams from different directions to sculpt the dose and focus it on areas that need it while pulling away from areas that don’t. She spoke about Northwestern group with John Kalapurakal leading using IMRT. While IMRT significantly reduces radiation exposure, there still is a small level of radiation scatter. She spoke about a paper at her institution using proton therapy. Proton therapy reduced radiation even more to the most unwanted areas. Protons stop in normal tissues in a way that x-rays do not, and with careful planning, the nuclear oncologist can make them stop before they reach non-target tissues.
The Children’s Oncology Group recommends early breast cancer screening for any patient who has had chest radiation using clinical breast exam, mammography, and MRI either eight years after completion of radiotherapy or age 25, whichever is later.
I wish you the very best.
Sincerely,
Frank Kalman
Calli’s Dad, DX 2001, 7 relapses, 7 major surgeries, over 500 weeks of chemotherapy (light and heavy)
Executive Director
End Kids Cancer