Predictors of Progression-Free Survival and Local Tumor Control after Percutaneous Thermal Ablation of Oligometastatic Breast Cancer: A Retrospective Study
What predicts local progression and progression-free survival following ablation of oligometastatic disease in breast cancer?
Thermal ablation can locally eliminate tumor progression for pulmonary, hepatic, bone and soft tissue oligometastatic disease in breast cancer if margins are greater than 5 mm.
Ridouani F et al. Predictors of Progression-Free Survival and Local Tumor Control after Percutaneous Thermal Ablation of Oligometastatic Breast Cancer: A Retrospective Study. Journal of Vascular and Interventional Radiology. July, 2020.
Figure 2. (Left column) Kalpan-Meier analysis demonstrates PFS from the time of initial ablation for all patients (top), for eradication of disease vs control of disease groups (P = .05) (second row), ER-positive compared to ER-negative patients (P= .037) (third row), and by minimal ablation margin of 5 mm (P= .33). (Right column) Kaplan-Meier analysis shows TTP from initial ablation for all patients (top row), for eradication of disease vs control of disease groups (P =.29), ER-positive compared to ER-negative patients (P= .08) (third row), and by minimal ablation margin of 5 mm (P= .036) (bottom row). The x-axes are months, and the y-axes are proportion at risk. ER-receptor status and age ≤ 60 years old demonstrated significant improved PFS. Additionally, ablation margin ≥ 5 mm showed longer median TTP (13 versus 5 months). Adverse events were noted to be moderate in 8% of liver ablations and 28% in lung ablations.
Utilizing a single-center, retrospective database search, the authors identified 33 patients (46 ablations) with 5 or fewer enlarging or increasingly metabolically active breast cancer metastatic lesions who underwent thermal ablation to the lung, liver, bone, or soft tissues. Radiofrequency ablation, microwave ablation, or cryoablation was performed with computed tomography, positron-emission tomography, or magnetic resonance image guidance. 35 liver (76%), 7 lung (15%), and 4 soft tissue or bone (8%) metastases were treated. 78% of patients were estrogen receptor positive, 51% progesterone receptor positive, 27% human epidermal growth factor receptor (HER2) positive, and 9% were triple negative. The median time from metastatic diagnosis wot ablation was 39 months. All patients received systemic chemotherapy, hormone therapy, or targeted therapy. Additionally, some patients also had surgical, radiation, or trans-arterial treatment.
91% of the procedures had technical success defined as no residual disease on initial post-procedure imaging. Local tumor progression was noted in 5 patients (15%) at 4-9 months following ablation. Ablation margins were measured in 83% of ablations with median margin being 6 mm. Median overall survival from first ablation treatment was 70 months with 1, 3, and 5 year survivals of 96%, 72%, and 55%. Median progression free survival was 10 months with median time to progression of 11 months.
With breast cancer being so common and greater than a quarter of these patients developing metastatic disease, this creates a large population of patients necessitating treatment. Studies have suggested that local treatment of breast cancer metastases may improve survival. This study added to this growing body of literature. Unsurprisingly, results were best in younger patients and larger margins. However, greater performance free survival was also seen in ER-positive patients.
Percutaneous ablation is clearly feasible and in appropriately selected patients have comparable results to surgery. Additionally, eradication of all disease can allow patients to take holidays from their systemic therapies.
Limitations include a small sample size, especially when considering four sites of disease and three ablation modalities. Additionally, image guidance used in this study, including PET/CT and MR guidance, is not widely available. However, clearly ablation should be included in the treatment paradigm who would benefit from treatment of their oligometastatic disease and tumor boards should consider this therapy in addition to surgery, radiation, and trans-arterial treatments.
David M Mauro, MD
Department of Radiology
Vascular and Interventional Radiology
University of North Carolina