In line with the clinical findings associating stress and enhanced recurrence rate in cancer patients [42,43,44,45,46,47,48,49], in vitro studies demonstrated that NE decreases the efficacy of chemotherapeutics [104], and pharmacological βAR activation in breast cancer cells was shown to promote tumor cell growth and migration [114], as well as the expression of inflammatory and chemotactic cytokines required for metastasis and carcinogenesis [53,115,116,117,118]. This evidence concerns the gene ADRB2 and breast cancer.