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ADT shows no link to dementia in prostate cancer
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Men with prostate cancer who underwent androgen deprivation therapy show no greater incidence of dementia, including Alzheimer disease, than those not treated with ADT, according to a large, population-based study published in Journal of Clinical Oncology.
“By using an appropriate study design and robust statistical analyses, we found that ADT use was not associated with an increased risk of dementia, including Alzheimer’s disease, in patients newly diagnosed with prostate cancer,” Farzin Khosrow-Khavar, MSc, a doctoral candidate at McGill University’s department of epidemiology, biostatistics and occupational health, told HemOnc Today. “This remained consistent in a number of other analyses that included duration of use and type of ADT. Overall, we believe that our findings should provide reassurance to patients using this therapy.”
Men with prostate cancer represent an older population already at increased risk of cognitive impairment and dementia; therefore, Khosrow-Khavar said it was imperative to assess whether ADT is associated with an increased incidence of dementia. Three previous observational studies showed conflicting results.
“Our study was specifically designed to circumvent the limitations of the previous studies,” Khosrow-Khavar said.
ADT is the typical treatment of patients with advanced prostate cancer and, although it has been shown to delay prostate cancer progression and improve survival, it has been associated with several adverse events — including fractures, type 2 diabetes, cardiovascular disease, acute kidney injury and possibly cognitive impairment.
A study published in JAMA Oncology involving 9,272 men with prostate cancer showed that those treated with ADT were more than twice as likely to develop dementia as those who were not.
Khosrow-Khavar and colleagues used the United Kingdom’s Clinical Practice Research Datalink to identify 30,903 men (mean age, 70.7 years; standard deviation [SD] = 8.9) who were newly diagnosed with nonmetastatic prostate cancer between April 1, 1988, and April 30, 2015. During a mean follow-up of 4.3 years (SD = 3.6), 799 men were newly diagnosed with dementia, generating an incidence of 6 per 1,000 person-years (95% CI, 5.5-6.4). This included 293 patients (36.7%) with Alzheimer disease and 506 patients (63.3%) with other dementias.
During the follow-up period, 17,994 patients (58.2%) used ADT, including 15,310 patients (49.5%) who were administered ADT within the first 6 months. The median duration of use was 2.3 years.
ADT users were older and more likely to have ever smoked. They were also more likely to have had higher PSA levels and greater prevalence of comorbidities.
Men treated with ADT did not have an overall increased risk for dementia (7.4 vs. 4.4 per 1,000 person-years; HR = 1.02; 95% CI, 0.87-1.19).
In secondary analyses, the risk for dementia did not vary with cumulative duration of use. Researchers reported similar results when assessing the association of ADT separately with Alzheimer disease (HR = 1.11; 95% CI, 0.85-1.44) and other dementias (HR = 0.97; 95% CI, 0.8-1.18).
“Because of the insidious nature of dementia, there may be misclassifications related to the exact date of onset of the disease,” Khosrow-Khavar and colleagues noted when describing limitations of the study. “However, we observed consistent results when lengthening the exposure lag period to 2 and 3 years. ... Additional studies in different settings are needed to confirm our findings.” – by Chuck Gormley
For more information:
Farzin Khosrow-Khavar, MSc, can be reached at farzin.khosrow-khavar@mail.mcgill.ca.
Disclosure: Researchers report no relevant financial disclosures. The study was funded through a foundation grant from the Canadian Institutes of Health Research.
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