PORTLAND, ORE. – Patients prescribed photosensitizing antihypertensive drugs had a 16% increase in risk of cutaneous squamous cell carcinoma (cSCC) in a large retrospective cohort study.
These drugs include alpha-2 receptor agonists and loop diuretics, potassium-sparing diuretics, thiazide diuretics, and combination diuretics, Katherine Levandoski said in an oral presentation at the annual meeting of the Society for Investigative Dermatology.
Furthermore, taking antihypertensive drugs of unknown photosensitizing potential conferred a 10% increase in risk of cSCC in the study, she added. Such medications include angiotensin–converting enzyme inhibitors, calcium channel blockers, and vasodilators, she said.
More than 50 million Americans take antihypertensive drugs, many of which are photosensitizing, noted Ms. Levandoski, a research assistant in the Patient Oriented Research on the Epidemiology of Skin Diseases Unit in the department of dermatology, Massachusetts General Hospital, and the department of population medicine, Harvard University, Boston. However, few studies have explored the oncogenic effects of exposure to these drugs, and those that have done so were subject to confounding, small sample sizes, missing data, lack of pathologic verification, and reliance on self-reported medication history, she added.
To help fill this knowledge gap, she and her associates studied 28,357 non-Hispanic whites diagnosed with hypertension and treated at Kaiser Permanente Northern California between 1997 and 2012. They limited the cohort to non-Hispanic whites because they represent the group with most cases of cSCC.
During follow-up, 3,010 patients were diagnosed with new-onset, pathologically verified cSCC, Ms. Levandoski said. Compared with nonusers of antihypertensives, users of photosensitizing antihypertensives had about a 16% increase in the rate of cSCC (hazard ratio, 1.16; 95% confidence interval, 1.06-1.27), even after accounting for age, sex, smoking, comorbidities, health care utilization, skin cancer history, length of health plan membership, and prior exposure to photosensitizing medications.
Strikingly, patients who used antihypertensives of unknown photosensitizing effect had a 10% increase in risk of incident cSCC (RR, 1.10; 95% CI, 1.02-1.19). Some antihypertensive drugs that are classified as unknown photosensitizers “may actually have photosensitizing properties,” Ms. Levandoski commented. Patients taking antihypertensives of known or unknown photosensitizing potential “should be educated on safe sun practices and may benefit from closer screening for cutaneous squamous cell carcinoma,” she added.
The risk of cSCC was not increased among users of nonphotosensitizing antihypertensives (HR, 0.99; 95% CI, 0.91-1.07), including alpha-blockers, beta-blockers, central agonists, and angiotensin receptor blockers, Ms. Levandoski reported.
Patients in the study cohort averaged aged 60 years (standard deviation, 10.6 years), and 56% were female. In all, 1,530 had never been prescribed antihypertensives, while about 17,000-19,000 had been prescribed unknown, known, or nonphotosensitizing antihypertensives.
The work was funded by the National Institutes of Health, a travel award from the Society for Investigative Dermatology, and a Massachusetts General Hospital Medical Student Award. Ms. Levandoski had no conflicts of interest.