The purpose of this study will be to evaluate, in a multi-center setting, the ability of radiofrequency ablation (RFA) of breast cancer lumpectomy sites to extend the "final" negative margin and consequently decrease the rates of re-operation. During the initial breast conservation procedure (lumpectomy), immediately following routine surgical resection of the tumor, radiofrequency energy (RFA) is applied to the wall (bed) of the fresh lumpectomy cavity, thus extending tumor free margin radially beyond the volume of the resected specimen.

Inclusion Criteria:

• Patient is a female, ≥ 50 years of age
• The tumor size is ≤ 3 cm (on pre-study radiologic OR clinical exam)
• The tumor is unicentric and unilateral
• The tumor is not involving the skin
• Pathology confirms ductal in situ (DCIS) OR infiltrating ductal carcinoma (IDC), grade I-III
• If tumor is IDC, pathology must be hormone receptor positive (ER+ and/or PR+)
• Patient signs current written informed consent and HIPAA forms

Exclusion Criteria:

• Patient is under 50 years of age
• Patient is male
• Tumor > 3 cm in diameter
• Bilateral malignancy
• Clinically positive lymph nodes
• Tumor involving the skin
• Pathology confirms invasive lobular carcinoma
• Breast implants
• Less than 2 years disease-free survival from previous breast cancer
• Neoadjuvant chemotherapy or chemotherapy for another breast cancer within two years