We hypothesize that SBRT initiated at the time of initiating chemo or shortly after is a feasible and durably effective means of systemic cytoreduction with the potential to delay or prevent the development of a lethal systemic burden of disease and increase progression free survival over systemic therapy alone.

Participant Eligibility

Biopsy proven invasive ductal or lobular metastatic breast cancer.

Age >= 18 years.

Patients must not have started Ixabepilone treatment more than 5 weeks prior to initiation of SBRT treatment.

Patients can have up to 6 sites of active extracranial disease(3 or increase of SUV>20% over a 6 month interval).

Patients with skin nodules, skin invasion, or skin ulceration are eligible, if treatment with conventional radiation (at discretion of radiation oncologist) or surgery is planned. SBRT to skin nodules is not advised because of risk of skin necrosis.

Patients must have had failure of an anthracycline and a taxane per FDA approved criteria.

Performance status of ECOG 0,1, or 2.

Adequate organ and marrow function as defined below:

- absolute neutrophil count >= 1,500/mcL
- platelets >= 100,000/mcl
- total bilirubin within normal institutional limits
- AST(SGOT)/ALT(SPGT) <= 2.5 X institutional upper limit of normal
- creatinine within normal institutional limits

Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.

A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:

* Has not undergone a hysterectomy or bilateral oophorectomy; or

* Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).

Patients who would be receiving SBRT for lung tumors who are known or must have a documented forced expiratory volume in 1 second (FEV1)>/=30%.

Must have a CT C/A/P, or PET/CT scan within 8 weeks of enrollment.

Ability to understand and the willingness to sign a written informed consent.