Leukemia after irradiation for endometrial cancer in Ontario.
BACKGROUND
In human studies, the risk of leukemia after ionizing radiation has been found to be increased more often than for any other cancer. It is useful to study patients with cancer treated with radiation because exposure can be measured accurately, follow-up may be long, and often a comparable and sizable nonexposed group exists. Women with endometrial cancer represent an excellent population for study because they meet these Developed Leukemia After Endometrial.


METHODS
A population-based matched case-control study, nested among all patients with endometrial cancer diagnosed in Ontario, was undertaken to describe the relationship between radiation therapy and leukemia risk. Among 13,843 subjects treated from 1964 to 1987 who survived at least 1 year, 47 confirmed cases of leukemia were identified. Four control subjects were matched to each patient based on age, calendar year of diagnosis, and length of survival free of a second neoplasm. Medical records were abstracted, and radiation dose administered to active bone marrow was determined by dosimetry.


RESULTS
An elevated risk of all leukemias other than chronic lymphocytic leukemia was observed, but only within the first 10 years after endometrial cancer treatment (odds ratio 12.0; 90% confidence interval 2.8-52.1). There was insufficient statistical evidence that risk was influenced by dose or type of radiation therapy. Nor was there any evidence that risk was influenced by age at endometrial cancer diagnosis or by calendar period at diagnosis.


CONCLUSIONS
There is an increased risk of leukemia associated with radiation therapy for patients with endometrial cancer, but only within the first 10 years after treatment.
Holowaty
E J
EJ
Ontario Cancer Treatment and Research Foundation, Toronto.
Darlington
G A
GA
Gajalakshmi
C K
CK
Toogood
P B
PB
Levin
W
W
D000368:Aged; D016022:Case-Control Studies; D016889:Endometrial Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D007938:Leukemia / Q000209:etiology*; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000209:etiology*; D016017:Odds Ratio; D009864:Ontario; D011878:Radiotherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012042:Registries; D013997:Time Factors