title: Increased incidence of myelodysplastic syndrome and acute myeloid leukemia following breast cancer treatment with radiation alone or combined with chemotherapy: a registry cohort analysis 1990-2005.
abstract: BACKGROUND
  Our objective was to measure myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML) risk associated with radiation and/or chemotherapy breast cancer (BC) treatment.
  
  
  METHODS
  Our study cohort was composed of BC patients diagnosed from 1990 to 2005 and followed up for blood disorders, mean length of follow up = 7.17 years, range 2-18 years. 5790 TNM stage 0-III patients treated with surgery alone, radiation and/or chemotherapy were included. Patients without surgery (n = 111), with stem cell transplantation (n = 98), unknown or non-standard chemotherapy regimens (n = 94), lost to follow up (n = 66) or 'cancer status unknown' (n = 67) were excluded. Rates observed at our community based cancer care institution were compared to SEER incidence data for rate ratio (RR) calculations.
  
  
  RESULTS
  17 cases of MDS/AML (10 MDS/7 AML) occurred during the follow up period, crude rate .29% (95% CI = .17, .47), SEER comparison RR = 3.94 (95% CI = 2.34, 6.15). The RR of MDS in patients age < 65 comparing our cohort incidence to SEER incidence data was 10.88 (95% CI = 3.84, 24.03) and the RR of AML in patients age < 65 was 5.32 (95% CI = 1.31, 14.04). No significant increased risk of MDS or AML was observed in women ≥ 65 or the surgery/chemotherapy-only group. A RR of 3.32 (95% CI = 1.42, 6.45) was observed in the surgery/radiation-only group and a RR of 6.32 (95% CI = 3.03, 11.45) in the surgery/radiation/chemotherapy group. 3 out of 10 MDS cases died of disease at an average 3.8 months post diagnosis and five of seven AML cases died at an average 9 months post diagnosis.
  
  
  CONCLUSIONS
  An elevated rate of MDS and AML was observed among breast cancer patients < 65, those treated with radiation and those treated with radiation and chemotherapy compared to available population incidence data. Although a small number of patients are affected, leukemia risk associated with treatment and younger age is significant.
authors.affiliation: Swedish Cancer Institute at Swedish Medical Center, Seattle, WA, USA. kaplan.hank@swedish.org
authors.forename: Henry G
authors.initials: HG
authors.lastname: Kaplan
authors.forename: Judith A
authors.initials: JA
authors.lastname: Malmgren
authors.forename: Mary K
authors.initials: MK
authors.lastname: Atwood
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D015470:Leukemia, Myeloid, Acute / Q000453:epidemiology / Q000209:etiology*; D007953:Leukemia, Radiation-Induced / Q000453:epidemiology / Q000209:etiology*; D008408:Mastectomy; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000453:epidemiology / Q000209:etiology*; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000209:etiology*; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D011878:Radiotherapy / Q000009:adverse effects*; D012042:Registries; D013997:Time Factors; D055815:Young Adult