Most regional anesthesia in breast surgeries is performed as postoperative pain management under general anesthesia, and not as the primary anesthesia. 
Regional anesthesia has very few cardiovascular or pulmonary side-effects, as compared with
general anesthesia. Pectoral nerve block is a relatively new technique, with fewer complications than other regional anesthesia. 
We performed Pecs I and Pec II block simultaneously as primary anesthesia under moderate sedation with dexmedetomidine for breast conserving surgery in a 49-year-old female patient with invasive ductal carcinoma. Block was uneventful and showed no complications. 
Thus, Pecs block with sedation could be an alternative to general anesthesia for breast surgeries.

Pectoral nerve block (Pecs block) with sedation for breast conserving surgery without general anesthesia