BrUOG 351: PRE-OPERATIVE APBI USING NIBB

Inclusion Criteria:

* Confirmed histological diagnosis of invasive breast carcinoma and/or DCIS (Invasive lobular carcinoma excluded);
* Age greater or equal to 60 years old;
* Life expectancy \> 6 months;
* Candidate for breast conserving surgery who intends to undergo breast conserving surgery as confirmed in writing by treating physician in consultation with surgeon
* Clinically lymph node negative (cN0) as confirmed in writing by patient's treating physician. If patient has suspicious lymphadenopathy on imaging it is required that patient undergo a biopsy to confirm cN0.
* Tumor size by imaging ≤ 2cm; (Tis or T1)
* Estrogen receptor positive if invasive disease (DCIS can be ER negative);
* Her2neu negative if invasive disease;
* Nuclear Grade 1 or 2 if invasive disease (DCIS can be Grade 3);
* ECOG performance status of 0-2 (Appendix 1);
* Informed consent signed.

Exclusion Criteria:

* Excisional biopsy or ipsilateral breast surgery within 6 months;
* Invasive lobular histology;
* Definitive LVSI on biopsy;
* Suspicious imaging findings suggesting multi-focal or multi-centric disease, unless biopsy proven benign;
* Paget's disease of the nipple
* Distant metastases;
* Known BRCA 1/2 Mutation
* Active lupus or scleroderma,;
* Psychiatric or addictive disorder that would preclude attending follow-up;
* Neoadjuvant chemotherapy or endocrine therapy (adjuvant therapy is permitted);
* Breast Implants;
* Tumor not well visualized on AccuBoost imaging;
* Breast separation with compression \> 8cm at time of simulation.