Curative-Intent Volumetric Modulated Arc Therapy for Locoregional and Oligometastatic HER2-Positive Breast Cancer: A Case Report
Keywords:
Breast cancer, VMAT, oligometastasis, radiotherapy, HER2-positive, curative therapyAbstract
Introduction:
Breast cancer is the most common prevalent malignancy in among women worldwide. Although metastatic breast cancer is generally regarded as incurable, the concept of oligometastasis—characterized by the limited spread of cancer to a few metastatic sites—offers the potential for durable remission through aggressive local treatment. Advanced radiotherapy techniques such as Volumetric Modulated Arc Therapy (VMAT) allow for precise delivery of high doses to complex targets with optimal protection of normal organs, making it suitable for curative use in selected cases.
Case Illustration:
A 52-year-old woman with a left breast mass was diagnosed with invasive carcinoma type of no special type (NST) grade II, HER2-positive, and hormone receptor-negative. Following a mastectomy and four cycles of chemotherapy, a single encapsulated lung lesion was discovered. The patient underwent external beam radiation on July 15, 2025, using the VMAT technique after CT simulators revealed internal metastases in the contralateral mammary lymph nodes. A curative dose of 50 Gy/25 fractions was administered to PTV50 and the locoregional area. Organ at Risk (OARs) doses: spinal cord 0.876 Gy, thyroid 2.601 Gy, esophagus 2.147 Gy, right lung 2.199 Gy, left lung 2.022 Gy, and heart 2.784 Gy. No post-radiation adverse effects were observed, and the patient was scheduled for further metastatic evaluation and continued chemotherapy.
Discussion:
This case highlights the potential role of VMAT in delivering radiotherapy with curative intent in HER2-positive breast cancer with limited metastases. VMAT offers superior dose conformity and protection of OARs compared to conventional 2D or 3D techniques. The literature supports metastasis-directed therapy, which achieves a 4-year overall survival of 59% and local control of 89%. Given the limited radiotherapy facilities in Indonesia, cases with curative intent such as this should be prioritized to minimize disease progression and optimize treatment outcomes.
Conclusion:
VMAT radiotherapy with curative intent represents a feasible and precise approach for managing both locoregional and oligometastatic breast cancer, with optimal tumor control and minimal toxicity. Adaptive treatment planning and timely delivery are crucial to maximize clinical outcomes, particularly in resource-limited settings.
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