Adjuvant chemotherapy for early breast cancer did not increase the risk for acute myeloid leukemia and myelodysplastic syndrome, according to results of a retrospective study.
Incidence rates of AML and myelodysplastic syndrome (MDS) in large populations of patients with breast cancer who receive pegfilgrastim (Neulasta, Amgen) or newer adjuvant regimens are not widely characterized, according to researchers.
Neelima Denduluri, MD, medical oncologist and hematologist at the Virginia Cancer Specialists, and colleagues used iKnowMed — an electronic health record from a large network of community oncology practices — to extract data about patients diagnosed with stage I to stage III breast cancer from 2007 to 2010.
All patients had at least five visits. Median follow-up was 2.8 years (range, 1.2-5.2 years).
Denduluri and colleagues identified 20,900 eligible patients; of them, 11,295 (54%) received chemotherapy and 9,605 (46%) did not. The median age of patients who received chemotherapy was 54 years. The median age for patients in the non-chemotherapy arm was 64 years (P<.01).
Among those treated with chemotherapy, 12 patients (0.11%) developed AML/MDS (95% CI, 0.06-0.19), with median time to onset of 1.8 years. Of those 12 patients, eight received anthracyclines and 11 received pegfilgrastim.
Among patients who did not undergo chemotherapy, 16 (0.19%) developed AML/MDS (95% CI, 0.11-0.3), with median time to onset of 2.2 years.
The low event rate in the study population may be due to short follow-up, younger age in the chemotherapy treated arm and/or high use of non-anthracycline chemotherapy, Denduluri said.
Multivariate analysis of patients who received chemotherapy showed patients aged 70 years or older were more likely to develop AML and MDS (HR=7.06; P<.01).
Those who received anthracyclines-containing chemotherapy were more likely to develop AML and MDS compared with those who received alternate regimens (HR=3.89; P=.04).
Denduluri N. Abstract #62.
Denduluri reports no relevant