Headline: Oligometastatic breast cancer does not appear to benefit from metastasis directed therapy.
The Study: The randomized EA2108 trial found that the addition of local therapy (surgery and radiation) to systemic therapy did not improve survival in patients with de novo metastatic breast cancer including the subset with oligometastatic disease. At ASTRO 2021, the CURB trial reported that mets-directed ablative radiation improved progression free survival (PFS) for oligoprogressive non-small cell lung cancer but not oligoprogressive breast cancer. So, does aggressive local therapy (SBRT or surgery) for oligometastatic breast cancer really make sense? BR002 enrolled patients with 4 or fewer breast cancer metastases and controlled primary disease with no evidence of progression on first-line systemic therapy. They were randomized to continue systemic therapy with or without metastasis-directed therapy (MTD). Most were hormone receptor-positive / HER2-negative (79%), had only a single metastasis (60%), and had metachronous metastatic disease (80%). The addition of MDT unfortunately did not improve median PFS (19.5 v 23 months with MDT) nor the rate of PFS at 24 months (47% v 46%) or 36 months (38% v 33%). While the rate of progression at index lesions was slashed with MDT (7% v 29%), most patients in both arms (40%) progressed at new sites. MDT appeared to be safe, though, with only slightly higher grade 3 events (10% v 5%) and no grade 5 events.
TBL: Once again, metastatic breast cancer—particularly the “indolent” variety—appears prone to subclinical metastatic disease with trajectories uninfluenced by local therapy to visible mets. | Chumra, ASCO 2022