A 46-year-old premenopausal woman with a body mass index of 21 was found on screening mammography to have a new, approximately 1-cm spiculated mass with associated calcifications in the upper outer quadrant of the left breast. Stereotactic core biopsy showed a focus of invasive duct carcinoma, strongly positive for estrogen and progesterone receptors and negative for human epidermal growth factor receptor 2, with associated ductal carcinoma in situ. Clinical examination revealed no palpable mass or axillary lymphadenopathy. She underwent a left lumpectomy with seed localization and sentinel lymph node biopsy. Final pathology revealed an 8-mm well-differentiated invasive carcinoma without lymphovascular invasion and intermediate grade ductal carcinoma in situ. The margins were clear, and three sentinel lymph nodes were negative for metastasis. The 21-gene recurrence score was 10, suggesting a 7% risk of 10-year distant recurrence with adjuvant endocrine treatment. After the completion of adjuvant radiotherapy (42.50 Gy in 16 fractions to the breast), the patient has returned for a follow-up visit. She is a professional violinist and would like to know what she can do to prevent lymphedema on her upcoming flight to Vienna.