Hopeful
10-10-2007, 06:34 AM
MedWire News: Breast cancer survivors face a small but significantly increased risk for secondary leukemia that persists for 25 years after initial diagnosis, reports a study.
It is becoming increasingly important to quantify the late adverse effects of cancer therapy, as more women are now surviving longer after breast cancer, explain Regan Howard (National Institutes of Health, Bethesda, Maryland, USA) and colleagues in the journal Breast Cancer Research and Treatment.
In the present study, the researchers identified 376,825 women who were alive at least 1 year after treatment for primary breast cancer. The women were followed-up for a median of 8.9 years between 1943 and 2001, with 21,084 women surviving for 25 years or more.
In total, 687 women developed secondary leukemia - 33 more than would be expected in the general population, note the researchers.
Breast cancer survivors had a particularly increased risk for chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL), and myeloid leukemia compared with the general population.
There was, however, an overall decrease in incidence of leukemia among breast cancer survivors from time periods before 1970 to time periods after 1985.
Specifically, the incidence of CML dropped markedly in this time period. The researchers note that CML is considered a carcinogenic consequence of ionizing radiation and speculate that this decrease is due to advances in radiation technology that permit more precise identification of target volumes, minimizing the dose received by surrounding tissues and bone marrow
On the other hand, there was a slight increase in incidence of ALL and AML, which the researchers say may be due to the use of topoisomerase II inhibiting chemotherapy, which has been linked to leukemia-causing chromosome rearrangements.
Howard et al call for further investigations to assess whether certain treatment modalities induce specific leukemia subtypes and to clarify patterns hinted at in the present study.
The researchers acknowledge that the benefits of systemic treatments for breast cancer outweigh the late adverse effects, although they caution that "health care providers should be aware that breast cancer survivors are at increased risk of leukemia for at least 25 years, with excesses observed for CML and ALL, as well as AML."
Breast Cancer Res Treat 2007; 105: 359-368
http://www.springerlink.com/content/dn4u7708185n1070/ (http://www.springerlink.com/content/dn4u7708185n1070/)
Abstract
Purpose 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.
Patients and 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.
Hopeful
It is becoming increasingly important to quantify the late adverse effects of cancer therapy, as more women are now surviving longer after breast cancer, explain Regan Howard (National Institutes of Health, Bethesda, Maryland, USA) and colleagues in the journal Breast Cancer Research and Treatment.
In the present study, the researchers identified 376,825 women who were alive at least 1 year after treatment for primary breast cancer. The women were followed-up for a median of 8.9 years between 1943 and 2001, with 21,084 women surviving for 25 years or more.
In total, 687 women developed secondary leukemia - 33 more than would be expected in the general population, note the researchers.
Breast cancer survivors had a particularly increased risk for chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL), and myeloid leukemia compared with the general population.
There was, however, an overall decrease in incidence of leukemia among breast cancer survivors from time periods before 1970 to time periods after 1985.
Specifically, the incidence of CML dropped markedly in this time period. The researchers note that CML is considered a carcinogenic consequence of ionizing radiation and speculate that this decrease is due to advances in radiation technology that permit more precise identification of target volumes, minimizing the dose received by surrounding tissues and bone marrow
On the other hand, there was a slight increase in incidence of ALL and AML, which the researchers say may be due to the use of topoisomerase II inhibiting chemotherapy, which has been linked to leukemia-causing chromosome rearrangements.
Howard et al call for further investigations to assess whether certain treatment modalities induce specific leukemia subtypes and to clarify patterns hinted at in the present study.
The researchers acknowledge that the benefits of systemic treatments for breast cancer outweigh the late adverse effects, although they caution that "health care providers should be aware that breast cancer survivors are at increased risk of leukemia for at least 25 years, with excesses observed for CML and ALL, as well as AML."
Breast Cancer Res Treat 2007; 105: 359-368
http://www.springerlink.com/content/dn4u7708185n1070/ (http://www.springerlink.com/content/dn4u7708185n1070/)
Abstract
Purpose 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.
Patients and 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.
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