medwireNews: Stereotactic radiosurgery (SRS) is associated with better long-term cognitive function than whole-brain radiotherapy (WBRT) in people with a limited number of brain metastases, suggests a secondary analysis of a clinical trial.
Reporting on the outcomes of trial participants who remained alive for at least a year after random assignment to receive SRS or WBRT, the researchers note that the late adverse cognitive effects of WBRT were “clinically meaningful and significant,” but the approach was associated with better intracranial tumor control at all timepoints.
They continue in JAMA Oncology: “Our data support the use of SRS alone after surgical resection as the standard of care, as was previously reported; however, our data suggest that the additional local and distant control gained by the use of WBRT may be important if the long-term toxic effects of WBRT [are] mitigated.”
The current analysis of the phase 3 Alliance N107C/CEC.3 study, which enrolled participants with a single resected brain metastasis and no more than three unresected metastases, included 54 patients (27 each in the SRS and WBRT arms) who were alive at 12 months from randomization. The most common primary tumor histology in the current cohort was lung, in 65%.
The proportion of patients who experienced cognitive deterioration – defined as a 1 standard deviation (SD) decrease from baseline in at least one of the six administered tests – was lower in the SRS than WBRT group at all timepoints, with rates in the SRS arm ranging from 37.0% at 3 months to 62.5% at 12 months versus 88.9% to 91.3% in the WBRT arm.
Similarly, a decline of 1.5, 2.0, or 3.0 SD from baseline in at least one, two, or three cognitive tests was less likely with SRS than WBRT. For instance, at 3 months, 22% of SRS-treated patients had a 2.0 SD decrease in one or more tests compared with 70% of those who underwent WBRT, while the rates at 6 and 9 months were 20% versus 46% and 20% versus 50%, respectively.
However, “[t]he rates of surgical bed control, local control, and distant control favored WBRT across the time points,” highlight Joshua Palmer (The James Cancer Center at The Ohio State University, Columbus, USA) and co-investigators.
For instance, the rates of local control of unresected brain metastases in the SRS group at 3, 6, and 12 months were 88.9%, 81.5%, and 70.4%, respectively, compared with 100%, 96.3%, and 92.3% in the WBRT group.
Similarly, the rates of total intracranial control were also lower with SRS than WBRT at all timepoints, at 88.9% versus 100% at 3 months, 70.4% versus 92.6% at 6 months, and 40.7% versus 81.5% at 12 months.
Palmer and colleagues also report on quality of life, which was assessed using the Functional Assessment of Cancer Therapy-Brain (FACT-Br) questionnaire. They found that mean changes in most FACT-Br domains tended to favor SRS at earlier timepoints, but by the 12-month mark, all but the additional concerns domain favored WBRT.
The study authors therefore summarize: “[T]he long-term effect of SRS and WBRT is not consistently in favor of 1 modality over the other for each patient-reported outcome or cognitive test, which may mean that there is a population of patients who still may benefit from early use of WBRT.”
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