Antihypertensive Medications and Risk of Skin Cancer in Older Individuals
Posted: Friday, May 14, 2021
For older patients who are both at elevated risk of skin cancer and in need of antihypertensive medication, a drug other than a thiazide diuretic should be considered, according to the results of a population-based study with more than 900,000 people published in the Canadian Medical Association Journal. An-Wen Chan, MD, DPhil, of the University of Toronto, Ontario, and colleagues found that increasing thiazide exposure was associated with higher rates of incident keratinocyte carcinoma, advanced keratinocyte carcinoma, and melanoma, with adjusted hazard ratios of 1.08, 1.07, and 1.34, respectively. They found no consistent evidence of an association between the use of agents in other antihypertensive classes—angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, and beta-blockers—and keratinocyte carcinoma or melanoma, the two types of skin cancer on which the study was focused.
The inception cohorts included Ontario adults 66 years and older, with data on record from 1998 to 2017. Each adult with a first prescription for an antihypertensive medication (n = 302,634) was matched with two adults prescribed a nonantihypertensive medication within 30 days of the index date (n = 605,268).
Some previous studies conducted at sites worldwide demonstrated similar results linking thiazide diuretic use and skin cancer, but they “were limited by deficiency of data on cumulative thiazide dosage, immortal time bias, a lack of accounting for polypharmacy, and treatment selection bias,” wrote Dr. Chan and co-investigators. Their study, in contrast, had “relevant comparison groups, time-varying cumulative exposure variables, large sample size, and standardized measurement of cumulative dose.” Nonetheless, they recommend that future studies should replicate their analyses in other populations and geographies, given the varying risk of skin cancer by latitude.
The scientists also suggested that the impact of current regulatory safety warnings related to thiazides and skin cancer should be evaluated for their real-world effectiveness. Finally, they stated, patients who do take thiazides should consider using sun protection consistently and being monitored for early signs of skin cancer.
Disclosure: The study authors’ disclosure information can be found at cmaj.ca.