Thiazide diuretics are among the most widely prescribed antihypertensive agents. However, in a study, researchers have reported that long term use of diuretics hydrochlorothiazide or indapamide is associated with an increased risk of developing specific types of skin cancer compared with patients who took calcium channel blockers. The research has been published in the British Journal of Dermatology on February 20, 2021.
Previous case‐control studies reported a dose‐dependent increased risk of skin cancer in users of hydrochlorothiazide (HCTZ) vs non‐users. However, the degree to which other thiazides and thiazide‐like diuretics (TZs) are associated with skin cancer is less certain. Therefore, researchers of the University of Basel, Switzerland, conducted a study to assess the risk of skin cancer in new users of different TZs compared to new users of calcium channel blockers (CCBs).
The researchers conducted a cohort study using a UK primary‐care database and identified patients who were aged 18 to 85 and who began taking thiazides, thiazide-like diuretics, or calcium channel blockers between January 1, 1998, and December 31, 2017. They included 271 154 new TZ users (87.6% bendroflumethiazide [BFT], 5.8% indapamide, and 3.6% HCTZ) and 275 263 CCB users. The major outcomes assessed were basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and cutaneous malignant melanoma (CMM). They determined the incidence rates (IRs) and IR ratios (IRRs) in short‐term (<20 prescriptions) and long‐term (≥20 prescriptions) users of TZs and CCBs using negative binomial regression and calculated rate differences (RDs) for selected results. The cohort was weighted by propensity score to control for 23 baseline covariates.
Key findings of the study were:
Upon analysis, the researchers found that long‐term use of HCTZ increased absolute and relative risks of SCC (PS‐weighted IRR, 1.95; RD per 100 000 person‐years, 87.4), but not of BCC or CMM.
They also found that long‐term use of indapamide was associated with an increased incidence of CMM (IRR, 1.43).
However, they noted that BFT was not meaningfully associated with the risk of any type of skin cancer.
The authors concluded, "Our results corroborate the previously reported increased risk of SCC (but not of BCC or CMM) for long‐term use of HCTZ. BFT may be a safer alternative for patients at increased risk of skin cancer."
For further information:
https://onlinelibrary.wiley.com/doi/10.1111/bjd.19880