medwireNews: Individuals who present with metastatic breast cancer do not experience improvement in overall survival (OS) or other outcomes with early locoregional therapy (LRT) for an intact primary tumor, according to ECOG-ACRIN 2108 trial findings.
Seema Khan (Northwestern University, Chicago, Illinois, USA), who presented the data at the virtual 2020 ASCO Annual Meeting, told delegates that a prior meta-analysis based on retrospective studies suggested a survival benefit of surgical resection in these patients, while two randomized trials reported conflicting data.
The current phase 3 study enrolled 390 patients who received optimal systemic therapy based on patient and tumor characteristics for 4–8 months, and the 256 (65.6%) who did not progress were randomly assigned to either receive early LRT (n=125; complete tumor resection and postoperative radiation as per guidelines) followed by systemic therapy or continue on systemic therapy alone (n=131).
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All but 14 of the patients in the LRT group underwent surgery, with 87 achieving negative surgical margins and 74 receiving locoregional radiotherapy. Twenty-five patients in the systemic therapy group also received surgery, “13 in the year following randomization, and 12 at a later time, all for palliation,” reported Khan.
Participants were followed up for 53 months, during which time there was “no hint […] of an advantage in terms of survival with the use of early local regional therapy for the primary site,” said Khan, with superimposable OS curves and median durations of 54 months in both study arms.
The OS data for the HER2-positive and the hormone receptor-positive, HER2-negative subgroups mirrored those of the overall study population, whereas patients with triple-negative breast cancer appeared to have a significantly higher risk for death with versus without use of early LRT (hazard ratio=3.50). But with just 20 patients in this subgroup, “the numbers are clearly too small to reach any conclusions,” the presenter cautioned.
The progression-free survival results for the total study cohort similarly showed no significant benefit of early LRT.
Nevertheless, patients who received early LRT had a significant 63% reduction in the risk for locoregional progression relative to their counterparts who did not. Specifically, locoregional progression – defined as regional nodal progression, chest wall disease, or invasive in-breast recurrence – occurred in 10.2% of the early LRT group, compared with a rate of 25.6% in the systemic therapy alone group, for whom locoregional progression was defined as the occurrence of symptoms leading to use of LRT.
However, this reduction in risk did not translate into a health-related quality of life benefit for the early LRT group. The FACT-B Trial Outcome Index scores at 18 months were significantly lower in the LRT than systemic therapy alone arm, and were comparable at other time points.
Khan therefore commented: “Based on available data, LRT for the primary tumor should not be offered to women with stage IV breast cancer with the expectation of a survival benefit.
“When systemic disease is well-controlled with systemic therapy but the primary site is progressing, LRT may be considered.”
She added that findings from the JCOG-1017 study, which has a very similar design to the current trial, are expected in May 2022 and are eagerly awaited.
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2020 ASCO Annual Meeting; 29–31 May