Radiation exposure
Residual node radiotherapy (RNRT) was delivered at a prescribed dose of 25.5 Gy in 17 fractions of 1.5 Gy, 2-4 weeks after completion of chemotherapy only to nodal sites that did not achieve a CR at the early response assessment (ERA) after two cycles of therapy.
“Patients treated with RNRT had significantly lower integral radiation dose compared with patients treated on HOD99 with [involved-field radiation therapy] (78.1 J vs. 249.6 J),” the authors wrote. “Doses to specific organs were also compared ... [t]he mean heart dose was reduced to 5.29 Gy from 16.9 Gy, and the mean thyroid dose was reduced to 4.46 Gy from 25.9 Gy.”
Women also had significantly less breast radiation exposure (mean of 3.21 Gy vs. 6.85 Gy in HOD99).
One irradiated patient experienced disease progression at the end of therapy, but remained disease free more than 6 years following salvage therapy, and one unexpected death occurred, the authors said.
“We have already reduced the use of radiation for low-risk Hodgkin lymphoma patients. In this study we’ve shown that it is also possible to either omit or reduce the extent of radiation for high-risk patients, using highly focal methods such as proton beam radiation or intensity modulated radiation,” co–senior author Matthew Krasin, MD, of St. Jude’s department of radiation oncology, stated in a press release.
Next steps
Co–senior author Melissa Hudson, MD, the St. Jude cancer survivorship division director, added that “[b]eing able to offer Hodgkin lymphoma patients a targeted therapy in the frontline setting is an exciting development.
“The favorable safety and toxicity profile of Bv in combination with chemotherapy for high-risk pediatric patients supports its prospective evaluation in a randomized trial,” the authors concluded, noting that “[l]onger follow-up is required to establish if this approach reduces risk of late-occurring toxicities such as second malignant neoplasms in this cohort of minimally irradiated patients.”
The study was sponsored by Seattle Genetics. The research at St. Jude was funded in part by grants from the National Cancer Institute and ALSAC (American Lebanese Syrian Associated Charities), St. Jude’s fundraising and awareness organization. Dr. Metzger reported research funding from Seattle Genetics. Dr. Krasin reported a consulting or advisory role for Debiopharm Group. Dr. Hudson reported a consulting or advisory role for Oncology Research Information Exchange Network, Princess Máxima Center.