Challenging and Successful Therapy Decision-Making for AML Post Cytotoxic Therapy and Concomitant Active Breast Cancer - A Case Report and Experience-Driven Strategy.

Breast cancer (BC) represents the most frequent female malignancy worldwide, and one of the rare, however life-threatening, complications after oncological treatment is acute myeloid leukemia post cytotoxic therapy (AML-pCT). Moreover, most AML-pCT cases have contributed to previous BC cytotoxic therapies. The treatment approach for AML-pCT in BC survivors with an active second BC represents the challenging decision-making process that is described in this report. A 48-year-old woman was diagnosed with invasive lobular carcinoma of the right breast (T2N0M0, BRCA1 negative) and successfully treated with breast-conserving therapy, adjuvant radiotherapy, and hormone therapy. Seven years later, she was diagnosed with ductal carcinoma in situ in the left breast, and unexpectedly, directly before the surgery, with leukocytosis, anemia, and thrombocytopenia. Hematological investigation revealed a diagnosis of AML-pCT (intermediate ELN2022 risk group). After a management conference involving both oncologists and haematologists, conserving surgery of the left breast (pTis, pNX) was performed. Seven days later the patient started intensive antileukemic treatment with "3+7" induction chemotherapy, followed by two consolidation chemotherapies, which resulted in complete remission (CR) of leukemia with negative measurable residual disease. Despite a high hematopoietic cell transplantation comorbidity index score (due to a previous neoplasm), the patient qualified for allogeneic hematopoietic cell transplantation (alloHCT). The procedure was performed using myeloablative conditioning with a matched unrelated donor. Currently, 3 years post-alloHCT, the patient remains in CR for all three neoplasms. In this case report, we describe the therapeutic success of intensive alloHCT in AML-pCT patient with active BC. The presented treatment approach for active BC and AML-pCT requires collaboration between oncologists and hematologists to ensure fast decision-making.