A case of synchronous breast and bilateral lung cancers: literature review and considerations for radiation treatment planning

Limited literature is available regarding treatment strategies for three concurrent potentially curable malignancies, and only one case of primary breast cancer with bilateral primary lung cancers has been reported. There is no literature available on approaches to radiation treatment planning and delivery in this challenging scenario. We report a case of a 66-year-old female who underwent partial mastectomy and sentinel node biopsy for left-sided breast cancer, pT1cN1(mic). Metastatic work-up revealed bilateral primary lung cancers, biopsy-proven, each Stage cT1N0. Distinguishing synchronous primary tumours from metastatic disease can be challenging. The histological examination suggested three distinct primaries and each was potentially curable. Devising a treatment strategy required balancing the incremental benefits with the toxicity of combining each of the treatments. Stereotactic ablative radiotherapy was the treatment of choice for the patient's lung primaries, as she was deemed a high-risk surgical candidate. Tangential whole breast radiotherapy with regional nodal irradiation was deemed appropriate for her breast cancer. Treatment for all three sites was planned concurrently, taking into account any potential overlap of dose in the composite plan. Each lung lesion was treated with 48 Gy in 4 fractions with stereotactic ablative radiotherapy using volumetric modulated arc therapy technique. The breast and supraclavicular regions were treated with 50 Gy in 25 daily fractions using a field-in-field technique. Optimal clinical outcomes for patients with multiple primary cancers require optimal definitive management. In this unique case of triple primaries, curative-intent radiotherapy to both lungs, the left breast and regional nodes was planned to be given concurrently and treatment was successfully delivered without significant toxicity.