Safe chemotherapy and hormone therapy for treating early breast cancer in a glucose 6-phosphate dehydrogenase-deficient patient: case report.

Breast cancer is the leading cause of neoplasia-related deaths among women, but no data are available in the literature on the safe use of oncological treatments in glucose 6-phosphate dehydrogenase (G6PD)-deficient patients. This case report describes, for the first time, the treatment of a G6PD-deficient woman diagnosed with breast cancer who underwent adjuvant treatment after quadrantectomy and axillary node dissection. After conservative surgery, many patients require adjuvant treatment with hormone therapy (HT) and/or chemotherapy. Anthracyclines are considered a cornerstone in this setting but, because of their oxidative properties, are contraindicated in G6PD-deficient patients. Despite the absence of data in the literature on their use in G6PD-deficient patients, we chose to use docetaxel and cyclophosphamide because these agents were not predicted to elicit oxidative stress. The patient completed six cycles of docetaxel and cyclophosphamide chemotherapy, and no adverse reactions were observed. Tamoxifen was excluded as a HT as a nonoxidative agent was required; therefore, an aromatase inhibitor was used as adjuvant therapy. Considering the high frequency of breast cancer and G6PD deficiency worldwide, there are little data available in the literature on the oxidative properties of oncological drugs. The oncological community must report cases in which patients with hereditary enzymatic deficiencies are treated successfully with anticancer agents. This would enable clinicians to have access to data that would be very useful in the choice of a safe treatment program.