It’s called stereotactic body radiotherapy (SBRT) or stereotactic ablative radiotherapy (SABR) and initial results from a phase II, multi-center clinical trial indicate that this approach can extend long-term survival for some patients with late-stage cancers while at the same time maintaining their quality of life.
“Despite many advances in cancer care over the last 20 to 30 years, some patients still go on to develop metastatic or stage-IV disease. Generally speaking, radiation therapy in that setting has been used only to make the patient comfortable”, explained Dwight E. Heron, MD senior author of the study and director of radiation services at UPMC Hillman Cancer Center in Pittsburgh.
While uncommon, some stage IV patients have seen their tumors shrink and with surgery have their metastasis removed and continue living for a long time. This prompted investigators to try stereotactic radiation, a form of high-precision cancer therapy that delivers higher doses of radiation to the affected area over the course of one to five sessions.
“With stereotactic radiation, we use a different type of highly precise local therapy to target tumors in the lungs, liver, bones or kidneys with precision that is analogous to surgery, and with very few side effects or harm to the patient’s quality of life”, noted Dr. Heron.
147 participants across three large cancer centers took part in trials aimed to evaluate the safety and feasibility of stereotactic radiation across a number of oligometastatic cancers – cases where the disease had been previously treated but then returned. Patients had up to five metastases, the majority (71%) having one or two (19%) in one to three new sites. Tumors were located commonly in the lung (52%), lymph nodes (16.5%), bone (15%) or liver (7%).
Post treatment with stereotactic radiation, more than eight in ten patients (84 percent) survived at least one year, and four in ten (43 percent) survived 5 years or longer. The median overall survival (OS) time was 42.3 months.
Local recurrences were low, and more than half of the patients experienced complete (26%) or partial (26%) remission following treatment. The disease was stable in 32% of cases.
Overall treatment was well handled and only 10% of participants experienced increased adverse effects.
“In combination with immunotherapy, stereotactic radiation therapy may set a new bar for achieving better outcomes, lowering side effects and improving our patients’ quality of life”, concluded Dr. Heron.
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