Leukemia following breast cancer: an international population-based study of 376,825 women.
OBJECTIVE
To quantify long-term temporal trends in the excess absolute risk (EAR) of secondary leukemia among breast cancer (BC) survivors, using multivariate analyses to evaluate the effects of subtype, age at BC diagnosis, attained age, and calendar year.


METHODS
We identified 376,825 1-year survivors of BC within 4 nationwide, population-based cancer registries in Sweden, Denmark, Finland, and Norway (1943-2001). Estimates of EAR (per 100,000 person-years) were modeled using Poisson regression methods and cumulative risks calculated using a competing risk model.


RESULTS
A total of 687 non-chronic lymphocytic leukemias (EAR = 9.05; 95% confidence interval (CI) = 7.5-10.7) was reported. Significantly elevated risks were observed for the first time for chronic myeloid leukemia (CML) (EAR = 2.06; 95% CI = 1.3-2.9) and acute lymphoblastic leukemia (ALL) (EAR = 0.62; 95% CI = 0.2-1.1), in addition to acute myeloid leukemia (AML) (EAR = 5.00; 95% CI = 3.9-6.2). Excesses of CML, ALL, AML and all leukemias combined persisted over 25 years after BC diagnosis. For all leukemias, EAR decreased with increasing calendar year (P = 0.04) of BC diagnosis. Risk for all leukemia and AML by calendar year of BC diagnosis depended on age at diagnosis. For women diagnosed with BC after 1985, the 10-year cumulative risk of leukemia for those diagnosed before and after age 50 was small, 0.10% and 0.14%, respectively.


CONCLUSIONS
Although secondary leukemia is a rare event, BC survivors experience statistically significant excesses for at least 25 years after diagnosis, including CML and ALL. Decreasing leukemia risks in recent calendar years likely reflect changes in treatment.
Howard
Regan A
RA
Division of Cancer Epidemiology and Genetics, Department of Health and Human Services, National Cancer Institute, National Institutes of Health, Executive Plaza South, Suite 7091, Bethesda, MD 20892, USA. reganho@mail.nih.gov
Gilbert
Ethel S
ES
Chen
Bingshu E
BE
Hall
Per
P
Storm
Hans
H
Pukkala
Eero
E
Langmark
Froydis
F
Kaijser
Magnus
M
Andersson
Michael
M
Joensuu
Heikki
H
Fossa
Sophie D
SD
Travis
Lois B
LB
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007938:Leukemia / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology*; D007953:Leukemia, Radiation-Induced / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology*; D012307:Risk Factors