Abstract
INTRODUCTION: Breast cancer is the most common malignancy affecting women in US today. Radiotherapy used after breast-conserving surgery has been shown to decrease local recurrence while minimizing side effects. Peripheral neuropathy remains a common and well-known complication of radiotherapy for breast cancer; however, it is rarely associated with phrenic nerve palsy after treatment of breast cancer. CASE PRESENTATION: We describe a 66-year-old woman with a significant past medical history of chronic obstructive pulmonary disease and asthma who presented with hypoxia after completing radiotherapy for breast cancer. After ruling out other causes of hypoxemia, the patient was diagnosed with diaphragmatic dysfunction, likely caused by phrenic nerve palsy resulting from radiotherapy-induced neuropathy after treatment of breast cancer. CONCLUSION: This case is the first reported incidence of phrenic nerve palsy resulting from radiotherapy for breast cancer.