Two Studies Highlight Benefit of Stereotactic Body Radiotherapy in Locally Advanced Pancreatic Cancer
Two studies from researchers at Johns Hopkins Kimmel Cancer Center add to preliminary evidence that high-dose radiation treatment, or stereotactic body radiotherapy, appears to be safe and as effective as standard radiation treatment for certain patients with locally advanced pancreatic cancer.
Benefits of High-Dose Therapy
The studies also suggest, the researchers said, that stereotactic body radiotherapy may have some advantages over traditional radiation for some patients, because doses can be delivered over the course of 1 week as opposed to 6 or 7 weeks, which is the standard with conventional radiotherapy. Some patients also reported significantly less pain and no significant decrease in their quality of life after stereotactic body radiotherapy, the scientists found.
Overall, the two studies show that stereotactic body radiotherapy for locally advanced pancreatic cancer “appears to be at least as good as standard radiation, and in some cases it appears to be better,” said Joseph Herman, MD, MSc, Co-Director of the Johns Hopkins Pancreatic Cancer Multidisciplinary Clinic. He cautioned, however, that randomized trials would be needed to confirm these results.
Conventional or standard radiation is delivered in relatively low doses, usually daily over the course of several weeks. Stereotactic body radiotherapy uses a higher dose of carefully targeted radiation to treat tumors, delivered all at once or in a few fractionated doses.
Minimal Toxicities With Fractionated Therapy
In the first study, published by Herman et al in Cancer, researchers reported that patients experienced minimal gastrointestinal side effects—such as ulcers and intestinal inflammation—when stereotactic body radiotherapy is delivered in five separate, fractionated doses, rather than one large dose.
The prospective, multi-institutional study included 49 patients with locally advanced pancreatic cancer treated at The Johns Hopkins Hospital, Stanford Health Care, and Memorial Sloan Kettering Cancer Center. The patients received stereotactic body radiotherapy in five fractionated doses and chemotherapy with gemcitabine before and after the radiotherapy.
Four weeks after stereotactic body radiotherapy, all 22 patients who completed a quality-of-life questionnaire reported an 8-point reduction in pain from a baseline measure of 25, and their quality of life stayed the same.
Of the 49 patients who received the five doses, 5 patients developed one gastrointestinal side effect, compared to 9 of 16 patients (47%) who received the single-fraction stereotactic body radiotherapy regimen in a previous study.
In some cases, patients were able to have their tumors surgically removed with few or no cancer cells left behind, said Dr. Herman. Before treatment with chemotherapy and stereotactic body radiotherapy, these patients were thought to have tumors unsuitable for surgery.
“The majority of patients we treat with stereotactic radiation have tumors that cannot be safely or effectively removed by surgery, and therefore their average survival is only about a year,” Dr. Herman said. “So if 5 days of stereotactic radiation has outcomes equivalent to the 6 weeks of standard chemotherapy and radiation, then patients can spend less time receiving treatment and more time at home with their families.”
Dr. Herman said that the shorter treatment duration with stereotactic body radiotherapy could also give patients quicker access to full-dose chemotherapy. The long duration of standard radiation may delay full-dose chemotherapy, potentially giving cancers more time to spread.
Role of Stereotactic Body Radiotherapy in Pancreatic Cancer
In a second study, reported by Moningi et al in the Annals of Surgical Oncology, Dr. Herman and colleagues analyzed information on patients with pancreatic cancer who received stereotactic body radiotherapy and chemotherapeutic drugs at The Johns Hopkins Hospital between 2010 and 2014. Of 88 patients, 8 experienced severe gastrointestinal side effects, and 19 with tumors previously considered inoperable were able to have surgery after stereotactic body radiotherapy.
Pancreatic tumors can cling and grow around blood vessels, making them especially difficult to remove. “After we irradiate it with stereotactic body radiotherapy, the tumor changes to a form that can be more easily pried away from the vessel,” Dr. Herman said.
Stereotactic body radiotherapy isn't for all patients with pancreatic cancer, he warned. People who have tumors larger than 8 cm in diameter, or have a tumor that is invading the area of the bowel or the stomach, usually can't get stereotactic body radiotherapy because of the risk to normal tissues.
Dr. Herman said he plans to work with other clinicians and scientists to test combinations of stereotactic body radiotherapy with therapies that help the immune system fight cancer more effectively, such as a Johns Hopkins–developed experimental pancreatic cancer vaccine.
Dr. Herman is the corresponding author for both the Cancer and Annals of Surgical Oncology articles.
Funding for the studies was provided by the Claudio X. Gonzalez Family Foundation, the Flannery Family Foundation, the Alexander Family Foundation, the Keeling Family Foundation, the DeSanti Family Foundation, the McKnight Family, the My Blue Dots Foundation, and the Viragh Family Foundation Inc.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
