True statements regarding Paget's disease of the breast include that it

Paget's disease of the breast is unrelated to Paget's bone disease. It represents a small percentage (1-3%) of all breast cancers and is thought to originate in the retro areolar lactiferous ducts. It progresses toward the nipple-areola complex in most patients, where it causes the typical clinical finding of nipple eczema and erosion. Up to 20% of patients with Paget's disease have an associated breast mass, and these patients are more likely to have involvement of axillary nodes. Nipple-areolar disease alone usually represents in situ cancer; these patients have a 10-year survival rate of over 80%. In contrast, if Paget's disease presents with a mass, the mass is likely to be an infiltrating ductal carcinoma. The generally recommended surgical procedure for Paget's disease is currently a modified radical mastectomy. The validity of breast-saving surgery and adjuvant radiation therapy for patients without an associated mass is under investigation.