By Laura Williamson, Science Writer
Research presented in the Plenary Session compared quality of life outcomes between radiation therapy modalities for locally advanced breast and oropharyngeal cancers and looked at advances in radiation therapy for treating prostate cancer, bladder cancer and brain metastases resulting from non-small cell lung cancer. The session was moderated by Kenneth Rosenzweig, MD, FASTRO, of the Icahn School of Medicine at Mount Sinai in New York and Farzan Siddiqui, MD, PhD, CPE, FASTRO, of Henry Ford Hospital and Wayne State University in Detroit.
The session’s first presentation was given by Shannon MacDonald, MD, FASTRO, from Southwest Florida Proton Center in Estero, Florida. Dr. MacDonald presented “Phase III Randomized Trial of Proton vs. Photon Therapy for Patients with Non-Metastatic Breast Cancer Receiving Comprehensive Nodal Radiation: A Radiotherapy Comparative Effectiveness (RADCOMP) Consortium Trial: Health-Related Quality of Life Outcomes.”
This multi-institutional, phase III trial was the first large, randomized trial to compare proton to photon radiation for non-metastatic breast cancer, enrolling more than 1,200 patients. It found patients were more likely to recommend proton therapy and to choose that treatment again. However, patients reported both treatments delivered excellent health-related quality of life after six months of follow up. Future analyses from this trial will analyze differences in local-regional control between the two treatment arms and whether proton therapy can reduce the risk of long-term major cardiac events, the risk of cancer recurrence in the chest wall or the risk of treatment-related skin reactions.
“The successful completion of RadComp is a testament to the field's commitment to comparing technologies,” Dr. MacDonald said. “The bottom line is patients should feel reassured that they can receive high quality care with either proton or photon radiation therapy. While we await our primary endpoints, physicians should continue to select the appropriate modality of treatment for patients with breast cancer, taking into consideration patient and disease-specific factors as well as regional access and cost.”
Discussant Simona Shaitelman, MD, EdM, of MD Anderson Cancer Center in Houston, said although patients in both arms reported high satisfaction with their treatments, further information was needed to better contextualize the findings. Specifically, more information was needed to understand how advances in reducing skin toxicity might have affected RADCOMP study participants, and more detailed dosimetric information was needed to understand how radiation could be affecting the lungs, since patients reported higher than typical rates of shortness of breath. Dr. Shaitelman said the RADCOMP investigators should be congratulated for this pragmatic, randomized trial.
Next, David Thomson, MD, of The Christie NHS Foundation Trust and Manchester Academic Health Science Centre at the University of Manchester in the United Kingdom, presented “Primary Results for the Phase III Trial of Toxicity Reduction Using Proton Beam Therapy for Oropharyngeal Cancer (TORPEdO: CRUK/18/010).” This phase III randomized clinical trial compared intensity modulated proton therapy (IMPT) and intensity modulated radiation therapy (IMRT) for the treatment of locally advanced oropharyngeal cancer, finding no differences in long-term patient-reported physical quality of life or swallow function between the two modalities. Both treatments resulted in low rates (<2%) of late feeding tube dependence.
“Patients and physicians can be reassured that there is no requirement to use IMPT as an alternative to IMRT for the treatment of oropharyngeal cancer,” Dr. Thomson concluded.
Discussant Vinita Takiar, MD, PhD, of the University of Cincinnati College of Medicine, noted that while Dr. Thomson’s conclusions contradicted prior research, “this is not the first time scholars have put forth seemingly opposite conclusions. Seemingly incongruous conclusions are not only a part of the scientific method, they are an expected part of it.”
Methodological differences, uncontrolled variables, investigator bias, incomplete data collection and developments in the field since initial patient accrual could all play a role in the opposing conclusions, she said. She ended by saying that as future research takes a deeper dive into the question, what is important to remember is that “our patients are doing well and as a field, we should all be proud of this accomplishment.”
Rodney Ellis, MD, of the University of South Florida and Tampa General Hospital Cancer Institute, then presented “Primary Results from NRG-GU005: A Phase III Trial of SBRT vs Hypofractionated IMRT for Localized Intermediate Risk Prostate Cancer.”
This randomized, de-anonymized, international phase III trial showed treating intermediate risk prostate cancer with five fractions (36.25 Gy) of stereotactic body radiation therapy (SBRT) given over two weeks could be done safely and with fewer side effects than moderately hypofractionated radiation given over four (60 Gy in 20 fractions) or six (70 Gy in 28 fractions) weeks.
"Our findings may help assure patients with intermediate risk prostate cancer that they can be safely treated with SBRT, while experiencing lower risks for rectal side effects, incontinence and decreased sexual function,” Dr. Ellis said.
“SBRT for low and intermediate risk prostate cancer is clearly here to stay and may be a preferred standard of care,” said discussant Matthew Abramowitz, MD, of the University of Miami. But, he noted, “I think dose matters.” Dr. Abramowitz offered a comparison to the PACE-B trial, which used higher doses across the board. Additionally, he noted the potential benefits of rectal spacers in reducing toxicity in both trial arms.
Vedang Murthy, MD, DNB, DipEPP, of Tata Memorial Hospital, Mumbai, next presented “Bladder Adjuvant Radiotherapy (BART): Clinical Outcomes from a Phase III Multicenter Randomized Controlled Trial.”
“This is one of the first randomized studies to show that post-operative radiation therapy can meaningfully reduce pelvic relapses in bladder cancer,” Dr. Murthy said. “Pelvic relapse can be devastating for patients – extremely painful and almost impossible to treat. Our research shows that modern radiation therapy offers a way to prevent many of these recurrences and improve patients’ quality of life.”
Discussant Brian Baumann, MD, of the Springfield Clinic in Illinois proposed that the BART trial was the largest and arguably most important trial in adjuvant radiation therapy for locally advanced bladder cancer. There has been a growing interest in RT for this cancer, Dr. Baumann noted, as chemotherapy has not been shown to reduce local-regional failures in the bladder. Benefits extended to patients with node-positive disease, Dr. Baumann said, and the treatment was well-tolerated.
Lastly, Vinai Gondi, MD, of Northwestern Medicine Warrenville Cancer Center and Proton Center in Warrenville, Illinois, presented “Tumor Treating Fields (TTFields) After Stereotactic Radiosurgery (SRS) for Brain Metastases from Non-Small Cell Lung Cancer (NSCLC BM): Final Results of the Phase III METIS Trial.”
This study showed TTFields therapy after stereotactic radiosurgery (SRS) should be considered a potential new treatment option for patients with brain metastases resulting from non-small cell lung cancer (NSCLC).
“The addition of tumor-treating fields to stereotactic radiosurgery for brain metastases from non-small cell lung cancer significantly improved intracranial control without additive toxicity or decline in neurocognitive function and with a more pronounced benefit in patients receiving immune checkpoint inhibition,” Dr. Gondi said. “These phase III trial results provide a novel treatment option for brain metastasis patients seeking to optimize control of metastatic brain disease and avoid whole-brain radiotherapy.”
Discussant Helen Shih, MD, MS, MPH, FASTRO, of Massachusetts General Hospital in Boston, closed the session by noting “the importance of creativity in creating new therapies.”
Dr. Shih said TTFields were still not widely understood and offered to patients, but their potential should be explored. TTFields treatment requires patients to shave their scalp and carry a portable device that delivers therapy through scalp-mounted nodes. Approximately 10% of patients with glioblastoma are offered TTFields despite having FDA approval for this disease. However, many of the patients who might benefit from the treatment have terminal disease or similarly grim diagnoses. “My challenge to you is to innovate based on science. Offer patients the opportunity. Give hope,” Dr. Shih said.
