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⁣Major Blood Pressure Drug, Hydrochlorothiazide, May Cause Skin Cancer | By Benjamin Ryan | Virtually Modern Medicine
The widely used blood pressure medication hydrochlorothiazide (HCTZ) may cause non-melanoma forms of skin cancer according to a new study of Danish patients. The investigators studied the usage of HCTZ between 1995 and 2012 based on a national prescription registry. The authors of the study found that long term usage of HCTZ, which is a diuretic also used to treat water retention (edema), was associated with a higher rate of two types of skin cancer and that greater usage of the drug increased the risk of each.
The most common malignancy, non-melanoma skin cancer is diagnosed with increasing frequency these days, especially among older individuals. Exposure to ultraviolet (UV) light as well as skin phenotypes that raise an individual’s susceptibility to such harmful rays are major risk factors. Research also suggests that drugs that suppress the immune system may prompt these types of cancers, while aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) protect against them. Seeking to follow scientific leads suggesting an association between HCTZ and non-melanoma skin cancer, a Danish research team pored over a trove of data from five national health registries to amass a cohort of about 71,500 Danes diagnosed with basal cell carcinoma and some 8,600 people who developed squamous cell carcinoma between 2004 and 2012. Then they matched each of these individuals 1-to- 20 based on age and sex, resulting in a respective 1.4 million and 172,000 controls without each skin cancer.
Next, the investigators determined each individual’s cumulative use of HCTZ between 1995 and 2012 based on a national prescription registry. A total of 2.7 percent of those diagnosed with basal cell carcinoma and 2.1 percent of the comparison group had taken at least 50,000 milligrams of HCTZ over time, which is the equivalent of six years of continuous use. Such a high level of HCTZ use was seen in 10 percent of those who developed squamous cell carcinoma compared with 2.8 percent of the control subjects for this group.
After adjusting the data to account for various other risk factors that may have affected skin cancer risk, the researchers found that 50,000 mg–plus of HCTZ use was associated with a 1.3-fold increased risk of basal cell carcinoma and a 3.99-fold increased risk of squamous cell carcinoma, compared with not using the drug. Taking HCTZ for a longer period was linked to higher risk: Compared with non-use, those who had taken at least 200,000 mg of the drug over time had a respective 1.5-fold and 7.4-fold increased risk of the respective skin cancers.
Presuming that HCTZ does in fact cause these malignancies, study authors estimated that 0.6 percent of the basal cell carcinoma cases and 9 percent of the squamous cell carcinoma cases were brought on by use of the medication. The stronger association between taking HCTZ and squamous cell carcinoma parallels research suggesting that exposure to UV rays contributes more greatly to the development of that cancer compared with the basal cell form.
When the scientists broke down their data by different demographic subgroups, they saw little variation in the associations between HCTZ and the two forms of skin cancer. But they did identify a stronger link among females and younger people, possibly because women tan more than men and younger people are at less risk for skin cancer based on other factors, such as those related to aging.
HCTZ use was also more strongly associated with the development of skin cancers on parts of the body that receive more sun exposure, especially the legs, compared with such cancers elsewhere on the body. Together, these findings led the researchers to conclude that HCTZ’s association with skin cancer is likely mediated by UV exposure. The investigators did not find any associations between non-melanoma skin cancers and any other diuretics or blood pressure medications.
The study’s findings are buttressed by the enormous, high-quality data set at hand. However, the analysis lacked information on two key risk factors for these two types of skin cancer: UV exposure and skin genotype. That said, the authors believe that overall sun exposure habits would not likely be considerably different between those who did and did not use HCTZ. And while there was no information about the ethnicity or skin type of the members of the overall study cohort, most Danes are Caucasian.
The study authors concluded that HCTZ use “should be carefully considered, as several other high blood pressure medications with similar indications and efficiency are available, but without known associations with skin cancer.”
Source: ⁣⁣
⁣http://www.jaad.org/article/S0190-9622(17)32741-X/fulltext
Tags: #Hydrochlorothiazide #HCTZ #SkinCancer #VirtuallyModernMedicine @Pharmative
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