ADT ups risks of heart failure, arrhythmia in localized prostate cancer patients
Androgen deprivation therapy (ADT) carries an increased risk of certain cardiovascular disease (CVD) outcomes, namely heart failure, arrhythmia and conduction disorder, in men with localized prostate cancer, a recent study suggests.
Findings from a cohort of localized prostate cancer patients who initially underwent active surveillance indicated that ADT was associated with a greater risk of heart failure, especially among those without CVD history (adjusted hazard ratio [HR], 1.81; 95 percent CI, 1.40 to 2.32). [Br J Cancer 2017;doi:10.1038/bjc.2017.280]
Exposure to the hormone treatment also increased the risks of arrhythmia (adjusted HR, 1.44; 1.02 to 2.01) and conduction disorder (adjusted HR, 3.11; 1.22 to 7.91) but only among patients with pre-existing CVD.
“The observed increased risk of arrhythmia among ADT users in our study is consistent with the confirmed inverse association between testosterone level and prolonged QT interval, a strong risk factor for fatal arrhythmias,” the investigators said. [Am J Epidemiol 2011;174:412–415]
They also noted the possibility that prostate cancer patients with pre-existing CVD may be more susceptible to developing conduction disorders or that such patients are more likely to have greater healthcare utilization, be monitored frequently and, hence, more likely to be diagnosed with other CVD conditions.
A total of 7,637 patients comprised the study population, with nearly 30 percent (n=2,170) exposed to ADT during a median follow-up of 3.4 years. Of the patients, 78 percent (n=5,972) had no prior CVD history.
CVD events occurred in 2,061 patients over 31,255 person-years, with an incidence rate of 65.9 events per 1,000 person-years. Average time to a CVD event was 3.2 years.
Given that heart failure, arrhythmia and conduction disorder affect patients’ quality of life and morbidity, possibly compromising survival, the current study is said to provide the basis for identifying susceptible individuals for regular cardiac check-up.
“The implication is that patients with localized prostate cancer should be followed to minimize the health effects of androgen deprivation therapy on the cardiovascular system," said lead investigator, Dr Reina Haque from the Kaiser Permanente Southern California Department of Research & Evaluation.
Patients should consider and discuss the positive and negative effects of ADT with their physicians, Haque continued. “If they move forward with the therapy, patients should work with their physicians to adjust their lifestyle to reduce the risk of cardiovascular disease.”
Despite having a large population, a long-term follow-up and the ability to adjust for a comprehensive set of covariates, the study might be limited by residual confounding for indication with the possibility that some factors that might influence ADT use and its outcomes were not captured. Furthermore, only one subtype of ADT (ie, GnRH agonists) was examined and without distinguishing between intermittent and continuous ADT administration.
“Future observational studies need to examine CVD outcomes in prostate cancer survivors who have been diagnosed in more recent years when the newer GnRH antagonist drugs were launched into the market and follow them for sufficient time to compare the long-term safety of different subtypes of ADT,” the investigators said.