Unilateral extremity swelling may be secondary to two major causes in female patients with cancer, deep venous thrombosis (DVT) and lymphedema. In women of all ages, DVT is high on the differential diagnosis list for unilateral extremity swelling. However, in women with an underlying malignancy, DVT and lymphedema must both be considered. Appropriate diagnosis and treatment are necessary to improve the quality of life and function of the female patient with cancer.