Breast cancer after childhood cancer: a report from the Childhood Cancer Survivor Study.
BACKGROUND
Survivors of childhood cancer are at risk for secondary breast cancer. Other than previous chest radiation therapy, risk factors for secondary breast cancer have not been established.


OBJECTIVE
To identify risk factors for breast cancer among female survivors of childhood cancer.


METHODS
Retrospective cohort study.


METHODS
The Childhood Cancer Survivor Study (CCSS), a multicenter study of persons who survived more than 5 years after childhood cancer diagnosed from 1970 to 1986.


METHODS
Among 6068 women in the CCSS, 95 women had 111 confirmed cases of breast cancer.


METHODS
Standardized incidence ratios for breast cancer were calculated by using age-specific incidence rates in the general population. Breast cancer incidence was evaluated with respect to primary cancer diagnosis and therapy, age at and time since primary diagnosis, menstrual and reproductive history, and family history of cancer.


RESULTS
Breast cancer risk was increased in survivors who were treated with chest radiation therapy (standardized incidence ratio, 24.7 [95% CI, 19.3 to 31.0]) and survivors of bone and soft-tissue sarcoma who were not treated with chest radiation therapy (standardized incidence ratios, 6.7 and 7.6, respectively). Family history of breast cancer (relative rate, 2.7 [CI, 1.3 to 5.0]) and history of thyroid disease (relative rate, 1.7 [CI, 1.1 to 2.6]) were independently associated with increased risk, and exposure to pelvic radiation was protective (relative rate, 0.6 [CI, 0.4 to 0.9]). Age at primary cancer diagnosis and menstrual and reproductive histories did not statistically significantly modify risk.


CONCLUSIONS
This cohort has not yet attained an age at which breast cancer risk is greatest.


CONCLUSIONS
Survivors of childhood sarcomas and those who received chest radiation therapy are at risk for secondary breast cancer. When assessing a survivor's risk, clinicians should consider primary diagnosis, previous radiation therapy, family cancer history, and history of thyroid disease.
Kenney
Lisa B
LB
Children's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA. Lisa_Kenney@DFCI.harvard.edu
Yasui
Yutaka
Y
Inskip
Peter D
PD
Hammond
Sue
S
Neglia
Joseph P
JP
Mertens
Ann C
AC
Meadows
Anna T
AT
Friedman
Debra
D
Robison
Leslie L
LL
Diller
Lisa
L
D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000235:genetics / Q000473:pathology; D002648:Child; D005260:Female; D020022:Genetic Predisposition to Disease; D006689:Hodgkin Disease / Q000150:complications / Q000532:radiotherapy; D006801:Humans; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000473:pathology; D012189:Retrospective Studies; D012307:Risk Factors; D012509:Sarcoma / Q000150:complications; D017741:Survivors; D013959:Thyroid Diseases / Q000150:complications; D013997:Time Factors