Myelodysplastic syndrome after maintenance treatment with metronomic cyclophosphamide: weighing prolonged stable disease against late toxicity

Sara Carvalho; Carolina Duque; Susana Lisboa; Dulcineia Pereira; Miguel Abreu

doi:10.5114/wo.2026.159746

eISSN: 1897-4309
ISSN: 1428-2526

Contemporary Oncology/Współczesna Onkologia

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abstract:

Case report

Myelodysplastic syndrome after maintenance treatment with metronomic cyclophosphamide: weighing prolonged stable disease against late toxicity

Sara Neves Carvalho

¹

,

Carolina Perez Duque

²

,

Susana Lisboa

³

,

Dulcineia Pereira

⁴

,

Miguel H. Abreu

¹

Medical Oncology, Portuguese Institute of Oncology – Porto FG, EPE, Porto, Portugal
Surgical Pathology Department, Portuguese Institute of Oncology – Porto FG, EPE, Porto, Portugal
Cancer Genetics Group of CI-IPOP, Portuguese Institute of Oncology – Porto FG, EPE, Porto, Portugal
Department of Haematology, Portuguese Institute of Oncology – Porto FG, EPE, Porto, Portugal

Contemp Oncol (Pozn) 2026; 30 (1)

DOI: https://doi.org/10.5114/wo.2026.159746

Online publish date: 2026/03/03

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Metronomic cyclophosphamide is occasionally used as maintenance therapy for patients with metastatic triple-negative breast cancer (TNBC), although there is limited long-term safety data. In this case study, we present the patient with metastatic TNBC who achieved a durable complete response and subsequently received metronomic cyclophosphamide for seven years. Progressive cytopenias prompted an investigation, which revealed myelodysplastic syndrome with monosomy 7 once reversible causes had been addressed, including vitamin deficiencies, Helicobacter pylori infection and previous hepatitis C exposure. Following discontinuation of cyclophosphamide, gradual haematological recovery was observed, and the patient remains without radiological evidence of progression. This case highlights the potential for late haematological toxicity associated with prolonged exposure to low doses of alkylating agents, emphasises the need for periodic reassessment of maintenance therapy in long-term responders, and shows that persistent cytopenias require evaluation of alternative causes rather than being solely attributed to chemotherapy.

keywords:

Myelodysplastic syndrome after maintenance treatment with metronomic cyclophosphamide: weighing prolonged stable disease against late toxicity

Sara Neves Carvalho 1 , Carolina Perez Duque 2 , Susana Lisboa 3 , Dulcineia Pereira 4 , Miguel H. Abreu 1

triple-negative breast cancer, maintenance therapy, metronomic chemotherapy, therapy-related myelodysplastic syndrome

Sara Neves Carvalho

¹

,

Carolina Perez Duque

²

,

Susana Lisboa

³

,

Dulcineia Pereira

⁴

,

Miguel H. Abreu

¹