Women with early-stage breast cancer are at elevated risk for atrial fibrillation (AF) short term and, to a lesser extent, long term, finds a large Canadian cohort study. Risk was higher for those who had received chemotherapy but not tied to specific cardiotoxic drugs or drug classes.
“Cardiovascular disease is a particularly pertinent clinical concern for women diagnosed with early-stage breast cancer,” note the investigators, led by Husam Abdel-Qadir, MD, PhD, FRCPC, Cardiology Clinic, Women’s College Hospital, Toronto. “Many early-stage breast cancer survivors are older than 65 years and have hypertension, diabetes, or left ventricular dysfunction. Accordingly, a diagnosis of AF would translate to a clinically relevant stroke risk for many early-stage breast cancer survivors.”
The investigators undertook a population-based retrospective cohort study of women in the province of Ontario with stage I-III breast cancer diagnosed between April 2007 and December 2016, matching them 1:3 to cancer-free control women on birth year and receipt of breast imaging.
An initial analysis, based on 95,539 breast cancer patients and 217,456 cancer-free controls, showed that the former and latter groups did not differ significantly on the prevalence of preexisting AF (5.3% vs. 5.2%; P = .21), according to results reported in JAMA Network Open.
Main analyses excluded women with preexisting AF, leaving 68,113 breast cancer patients and 204,330 cancer-free controls having a mean follow-up of 5.7 years. Both groups had a mean age of 60 years at baseline, and prevalences of cardiovascular comorbidities were similar. Within the breast cancer group, 50.4% had left-sided disease; overall, 53.2% received chemotherapy and 71.7% received radiation therapy.
At 10 years after diagnosis, breast cancer patients had a small but significant increase in AF incidence relative to control peers (7.4% vs. 6.8%; P less than .001). When the investigators looked at specific time periods, survivors had a significantly elevated AF risk in year 1 postdiagnosis (hazard ratio, 2.16) and after year 5 postdiagnosis (hazard ratio, 1.20), but not during years 2 through 5.
Analyses beginning 1 year after diagnosis showed a slightly smaller but still significant elevation of AF incidence for the breast cancer group at 9 years of follow-up (10 years after diagnosis) (7.0% vs. 6.5%; P less than .001).
Among breast cancer patients, those who received chemotherapy had a higher risk of AF than those who did not (adjusted hazard ratio, 1.23); however, this elevation of risk was not specifically tied to receipt of anthracyclines or trastuzumab (Herceptin) versus other chemotherapy. Risk was not elevated for those who received radiation therapy.
“Our study findings suggest that a diagnosis of early-stage breast cancer may be associated with a small increase in the risk of AF compared with that for cancer-free women,” Dr. Abdel-Qadir and coinvestigators noted. “Since the absolute risk is small, this finding does not warrant routine surveillance but rather should prompt consideration of AF in the differential diagnosis for women with compatible symptoms.
“The early and late periods of increased AF risk in early-stage breast cancer survivors warrant focused research to better understand the underlying causes and subsequent implications,” they concluded.
Dr. Abdel-Qadir reported receiving grants from the Canadian Cardiovascular Society during the conduct of the study, speaker fees from Amgen, and an honorarium for clinical events adjudication committee membership from the Canadian Vigour Centre for a study funded by AstraZeneca. The study was funded by the Canadian Cardiovascular Society Atrial Fibrillation Research Award.
SOURCE: Abdel-Qadir H et al. .