Characteristics and Outcome Of Acute Myeloid Leukemia Following Breast Cancer: Analysis Of 408 Cases and Controls

With the improvement of cancer therapy, long term survivors are more exposed to the risk of secondary myeloid neoplasm including myelodysplasia and acute leukemias. The WHO 2008 classification individualize the therapy related acute myeloid leukemia (AML) as a specific entity and highlight the role of chemotherapy/radiotherapy in the pathogenesis of the disease. There is a demonstrated link between specific therapeutic agents, recurrent genetic lesions (such as t(15;17), CBF AML, monosomy 7, …), and outcome. However, most of the published series include multiple types of primary cancer and treatments. This heterogeneity may represent a problem as only limited data are available in patients with specific cancer subtypes, such as the most frequent one, breast cancer. This may be important at a public health level but also to homogenize age and types of prior treatment. Moreover, the complexity of t-AML could not be resumed to the association between treatment and karyotype, as some patients developed AML without chemotherapy, suggesting a potential predisposition to AML. In the present report, we focused on AML arising after breast cancer (BC) and describe the characteristics and outcome of this population.

This is a retrospective multicenter study. Patients were included if they had the diagnosis of breast cancer preceding diagnosis of acute myeloid leukemia whatever may be the interval between the 2 cancers and whatever treatment was administered for BC. All patients with AML were treated with induction chemotherapy. Clinical and biological data for both cancers were collected. Patient’s characteristics and results were compared with age, cytogenetic risk, and optionally sex matched (if possible) de novo AML with a 2/1 ratio.

408 patients were analyzed, including 136 AML associated with BC and 272 de novo AML. The median age at diagnosis of BC was 50 years. 47% of patients had invasive ductal carcinoma. Treatment of BC included chemotherapy in 81% of cases, radiotherapy in 91% of cases, and surgery in 99% of cases. The median time between BC and AML was 2.8 years. Median WBC was 3.4G/l and median platelets count was 49G/l. For AML-BC, Cytogenetics were abnormal in 82% of cases including 12% Complex Karyotype, 12% t(15;17), 17% CBF, and 20% MLL translocations. The recent introduction of taxanes in the treatment of BC did not seem to change the frequencies of these aberrations. With the exception of sex ratio, there was no significant difference of baseline characteristics as compared to control group. Regarding induction chemotherapy, CR rate was 81% and 8-week mortality 11.6%. In the control cohort, CR rate was 83% (p=NS) and 8 week mortality 7% (p=NS). Allogeneic transplantation was performed in 21% and 17% of patients respectively. In cytogenetic adjusted survival analysis, median overall survival and relapse free survival were similar between AML-BC and de novo AML for favorable risk (OS and RFS not reached for both groups; p=0.06 and p=0.3 respectively), and unfavorable risk (OS 12m vs. 13m p=NS, RFS 8m vs. 9m p=NS) groups. Interestingly, there was a difference for intermediate cytogenetics group, with median OS (21 months vs. 38 months p=0.01) and median RFS (14 vs. 25 months p=0.04). Difference was also confirmed for cumulative incidence of relapse (1 year probability 41% vs. 22%, p=0.04). Frequency of FLT3, NPM1, and CEBPA mutations were only available in a subset of patients. Only 1/12 pts in the intermediate AML-BC group was FLT3 mutated and 1/12 pt had isolated NPM1 mutation. In the de novo cohort, 11/28 pts had FLT3 mutations and 8/21 pts had isolated NPM1 mutation.

Our data showed that in AML arising after BC, the prior BC do not appear to impact the outcome in favorable and unfavorable cytogenetic risk groups. However, this is different for intermediate risk cytogenetics, our data suggesting a poorer outcome of AML-BC and potentially a different mutational profile. Regarding AML susceptibility, a matched pair analysis comparing the AML-BC and BC without AML will also be presented at the meeting.

No relevant conflicts of interest to declare.