Therapy-related myelodysplastic syndrome following primary breast cancer

• t-MDS risk post breast cancer was 30 times that expected among younger patients.
• Shorter time from t-MDS diagnosis to death was observed in younger patients.
• Shorter time from t-MDS to death occurred with multiple cytogenetic abnormalities.
• Only patients treated with stem cell transplantation obtained cure.
• Annual complete blood counts may be warranted for younger breast cancer patients.

BackgroundTherapy-related myelodysplastic syndrome (t-MDS) is a serious clinical disease occurring after breast cancer treatment.MethodsA cohort of 11,684 invasive breast cancer (BC) patients from 1990–2014 were followed for incidence of t-MDS through institutional and the Surveillance, Epidemiology and End Results (SEER) Program registries. t-MDS cases were identified using ICD-O SEER registry codes, pathology and chart reports. Treatment, cytogenetics, and time from BC diagnosis to t-MDS and t-MDS diagnosis to last follow up or death were obtained. Incidence rate ratios were calculated using SEER national incidence rates for comparison.Results27 cases of t-MDS post BC treatment were confirmed. 96% of cases were breast cancer stage I–II at diagnosis. All patients had received radiation treatment and 59% received adjuvant chemotherapy. Two patients were alive with no evidence of disease after treatment with stem cell transplantation (age 33 and 46). t-MDS incidence was 30 times the expected population rate among patients <55 years (RR 31.8, 95% CI 15.0, 60.8) with shorter time from t-MDS diagnosis to death (median survival time: <55: 8 months, 55–74: 26 months, 75+: 23 months).ConclusionWe found elevated t-MDS risk especially among younger BC patients with stem cell transplantation the only observed curative treatment.