Abstract 17486: Age and Sex Differences in Risk of Cancer With Low Dose Ionizing Radiation From Cardiac Imaging Procedures After Acute Myocardial Infarction
Background: Age and sex may modulate the excess risk of cancer associated with low dose ionizing radiation (LDIR) owing to more radiosensitive tissue in younger adults and breast cancer in females. Our objective was to measure the effect of age and sex on LDIR-associated risk of cancer in patients with acute myocardial infarction (AMI) exposed to LDIR from cardiac imaging procedures.
Methods and Results: A longitudinal population-based cohort of men and women with AMI between 1996-2006 was assembled from an administrative database in Quebec. Patients with a prior or recent diagnosis of cancer were excluded. The exposure variable was cumulative dosage of LDIR from cardiac imaging procedures with a time lag of 1 year added to each exposure. The primary endpoint was incidence of cancer. Time-dependent Cox proportional hazards analysis was performed with age, sex, and LDIR in the model. Interaction was tested by two methods. First, interaction terms for age and LDIR, and sex and LDIR, were entered in the model. Second, stratified analyses were performed by sex and deciles of age. There were 26,255 females and 56,606 males in the cohort. For females, the median age was 71.7 years (Q1 60.2, Q3 80.1), the dose of LDIR was 3.7 mSv/year, and 3,545 new cancers were observed over 4.2 years (Q1 2.4, Q3 6.8). For males, the median age was 59.7 years (Q1 51.3, Q3 69.8), the dose of LDIR was 4.1 mSv/year, and 8,475 new cancers were observed over 4.8 years (Q1 2.7, Q3 7.4). The interaction term for sex and LDIR was significant (P<0.0001) whereas the interaction term for age and LDIR was not (P=0.14). For every 10 mSv increase in LDIR, the risk of cancer increased by 4.4% in females (adjusted HR 1.044; 95% CI 1.025, 1.064) and 2.1% in males (adjusted HR 1.021; 95% CI 1.009, 1.033).
Conclusion: Among AMI patients exposed to LDIR from cardiac imaging procedures, females faced a higher risk of LDIR-associated cancer than their male counterparts, whereas age was not a major determinant.
- © 2010 by American Heart Association, Inc.