By Laura Williamson, Science Writer
The Clinical Trials session focused on advances in radiation therapy that expanded treatment options for people with a wide range of cancers, improving the patient experience and reducing health care costs. The session was moderated by Kenneth Rosenzweig, MD, FASTRO, Icahn School of Medicine, Mount Sinai in New York City and Andrea Ng, MD, FASTRO, MPH, Dana-Farber/Brigham and Women’s Cancer Center in Boston.
The session’s first presentation was given by Bradford Hoppe, MD, MPH, FASTRO, from the Mayo Clinic in Jacksonville, Florida, whom Dr. Rosenzweig introduced as one of two recipients of the 2023 Leibel Memorial Award. The Award is given to early- to mid-career American Board of Radiology certified or board-eligible principal investigators chosen each year by the Annual Meeting Steering Committee based on their abstract’s peer-reviewed scores.
Dr. Hoppe presented “Consolidative Radiotherapy in Place of Autologous Stem Cell Transplant in Patients with Low-Risk Relapsed/Refractory (R/R) Classic Hodgkin Lymphoma (cHL) Treated with Nivolumab plus Brentuximab Vedotin.” In this study, investigators wanted to know if they could replace high dose therapy and autologous stem cell transplant — treatments that are costly and carry a high rate of adverse side effects — with the less intensive combination of nivolumab and brentuximab vedotin, followed by consolidative involved site radiation therapy (ISRT). Their findings suggest this treatment regimen is an effective second line therapy for children and young adults with low-risk relapsed/refractory classic Hodgkin lymphoma (RRHL).
“This regimen was very well tolerated with limited grade 3 treatment-related adverse events and no new toxicities detected within 100 days of follow-up,” Dr. Hoppe said. “The findings suggest children and young adults with low-risk, relapsed classic Hodgkin lymphoma can be salvaged with low toxicity chemoimmunotherapy and ISRT and may not require high dose therapy for cure.”
Next, lead study author Kathrin Kirchheiner, PhD, MSc, of the Medical University of Vienna in Austria, presented “Association Between Regular Vaginal Dilation and/or Sexual Activity and Long-Term Vaginal Morbidity in Cervical Cancer Survivors.” This large, multi-institutional study found regular sexual activity and/or use of a vaginal dilator could reduce the risk for long-term, irreversible side effects in people with cervical cancer who had been treated with a combination of chemotherapy, external beam radiation therapy and brachytherapy.
Those who had regular intercourse and used a vaginal dilator had the lowest risk of vaginal stenosis, followed by sexually active people not using dilators and people who only used dilators. The highest risk was for those who did neither. However, while the risk for vaginal stenosis was lower, regular dilation raised the risk for mild vaginal dryness and bleeding. “These data are based on correlations and do not represent a cause and effect so we cannot draw any solid conclusions,” Dr. Kirchheiner said. “But the long-term data support the clinical recommendation for dilation and sexual activity after radiation.”
“Curing cancer is always our first priority,” she said. “But with a growing number of relatively young cervical cancer survivors, the prevention and management of side effects becomes increasingly important to ensure a better quality of life.”
Shankar Siva, PhD, MBBS, of the Peter MacCallum Cancer Centre in Australia, presented “TROG 15.03/ANZUP International Multicenter Phase II Trial of Focal Ablative STereotactic RAdiotherapy for Cancers of the Kidney (FASTRACK II).” This multi-center, phase II trial found targeted, high-dose radiation achieved 100% local control and cancer-specific survival for longer than three years among older people with renal cell carcinoma whose tumors were inoperable.
Dr. Siva pointed out that kidney cancer has been increasing worldwide over the past several decades, most rapidly among people 70 and older, many of whom are at high risk for surgery or who have inoperable tumors. “We’ve demonstrated that a novel treatment — SABR — delivered in an outpatient setting is able to achieve unprecedented efficacy for patients with inoperable kidney cancer,” he said. “There’s an unmet need for curing this type of cancer and our findings point to the potential of radiation therapy to address that need.”
“Long-Term Follow-Up Analysis of NRG Oncology RTOG 0415: A Randomized Phase III Non-Inferiority Study Comparing Two Fractionation Schedules in Patients with Favorable-Risk Prostate Cancer” was presented by lead study author W. Robert Lee, MD, MS, MEd, FASTRO, Duke University Medical Center in Durham, North Carolina. Investigators provided a long-term update of this randomized trial, confirming that a hypofractionated radiation schedule was just as effective as — if not better than — a conventional radiation schedule for patients with low-risk prostate cancer. At a median follow up of over 12 years, they showed that long-term disease-free survival was non-inferior to conventionally fractionated radiation, biochemical failure was reduced with hypofractionation and there were no significant differences in late-grade 3 or 4 toxicity between the two arms.
“Long-Term Outcomes of NRG/RTOG 0126, a Randomized Trial of High Dose (79.2Gy) vs. Standard Dose (70.2Gy) Radiation Therapy (RT) for Men with Localized Prostate Cancer,” was presented by ASTRO President Jeff Michalski, MD, MBA, FASTRO, of Washington University in St. Louis. In the long-term update of this phase III trial for patients with localized prostate cancer, investigators confirmed that, at a median follow up of 12 years, escalating the radiation dose continued to have no effect on overall survival, but significantly improved the time to prostate cancer death, incidence of biochemical failure, time to local progression and time to distant metastases and need for salvage therapies. They also had higher rates of grade 2 toxicities, but there was no difference in grade 3 toxicities between the two arms.
Discussant Dayssy Alexandra Diaz Pardo, MD, MS, from The Ohio State University in Columbus, Ohio, said both Dr. Lee’s and Dr. Michalski’s studies “changed paradigms about how we treat prostate cancer” and could result in decreased costs to the health care system.
Next, “Patient-Reported and Toxicity Results from the FABREC Study: A Multicenter Randomized Trial of Hypofractionated vs. Conventionally Fractionated Postmastectomy Radiation Therapy After Implant-Based Reconstruction,” was presented by senior study author Rinaa Punglia, MD, FASTRO, MPH, of the Dana-Farber Brigham Cancer Center in Boston. In a first-of-its-kind study, investigators compared quality-of-life and clinical outcomes of hypofractionated and conventionally fractionated radiation therapy for people with breast cancer who underwent implant-based breast reconstruction immediately following a mastectomy.
They found the shorter-course radiation was just as effective as long-course therapy without increasing side effects and slightly improved quality of life for women under 45 years old, saving them time and money. Treatment breaks also were significantly reduced using hypofractionation.
“Enzalutamide or Placebo Plus Leuprolide Acetate and Enzalutamide Monotherapy in Men with High-Risk Biochemically Recurrent Prostate Cancer and Prior Radiotherapy: EMBARK Subgroup Analysis,” was presented by Swetha Sridharan, MD, Calvary Mater Newcastle Hospital in Waratah, New South Wales, Australia. This was a subgroup analysis from a phase III study of patients with high-risk biochemical recurrence treated with hormone therapy, comparing metastasis-free survival in people with and without prior radiotherapy.
Dr. Sridarhan’s team had previously shown treatment with the hormone combination therapy of enzalutamide plus leuprolide acetate and enzalutamide monotherapy were superior to placebo plus leuprolide acetate. This new subgroup analysis found the benefit may be limited to people who had prior radiation.
The session concluded with a presentation from Denise Bernhardt, MD, Technical University of Munich (TUM), Radiation Oncology in Bavaria, who reported findings from “Stereotactic Radiotherapy vs. Whole Brain Radiation Therapy for Patients with 1-10 Brain Metastases from Small Cell Lung Cancer: Results of the Randomized ENCEPHALON (ARO 2018-9) Trial.” This pilot trial was a prospective, randomized, two-arm phase II study to compare tumor control and neurocognitive risks in patients treated with stereotactic radiotherapy (SRT) versus those treated with whole brain radiation therapy (WBRT).
Dr. Bernhardt said WBRT has been the standard of care for patients with small cell lung cancer and brain metastases, even though there is low evidence to support this. In her study, she showed patients treated with WBRT had significantly greater risk for a decline in neurocognitive function three months following treatment than those in the SRT arm, with no significant difference in survival probability between the two groups. The findings led her to conclude that SRT should be considered a standard of care for people with brain metastases from SCLC.
These studies can be found in the Proceedings of the 2023 ASTRO Annual Meeting.
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