High blood pressure drug linked to skin cancer in older Australians

Cardiovascular disease

A UNSW Sydney study has found that the use of high blood pressure drug, Hydrochlorothiazide, increases the risk of developing skin cancer in older people.

The drug, which is one of the most prescribed high blood pressure drugs in Australia, contains photosynthesising properties, which can make skin more sensitive to the sun.

The findings are based on a big data analysis of skin cancer rates in a case-control study among older Australians.

The results, published in Basic & Clinical Pharmacology & Toxicology, support similar findings from previous international studies.

“We found increased risk for developing malignant melanoma and squamous cell cancer of the lip (lip cancer) with hydrochlorothiazide use,” says Dr Benjamin Daniels, lead author of the study and research fellow at UNSW Medicine’s Centre for Big Data Research in Health (CBDRH).

A pharmacoepidemiologist, Dr Daniels studies the use and effects of drugs in specific population groups.

“For lip cancer, the risk also appears to be cumulative – that is, the longer that hydrochlorothiazide is used, the higher the risk of developing lip cancer.”

Management of high blood pressure – or hypertension generally requires prescribed medicine, like hydrochlorothiazide, alongside lifestyle changes.

“Hypertension is a condition that needs to be carefully managed,” says Dr Daniels.

“We don’t want anyone to suddenly stop taking hydrochlorothiazide out of fear of developing skin cancer.

“The skin cancer risk is something for prescribers to be aware of. Doctors may want to consider conducting more skin checks for their patients or reinforcing advice around sun-smart behaviours that everyone should be aware of, like adequate protection when UV is higher than three and avoiding sun exposure during peak UV times.”

Doctors may want to conduct more skin checks for their patients or reinforce advice around sun-smart behaviours following the new findings.

To reflect this newly understood risk, the product information has been updated for medicines containing hydrochlorothiazide.

“This [update] will help prescribers and patients to make informed choices about the benefits and risks of hydrochlorothiazide-containing medicines,” a spokesperson from the Therapeutic Goods Administration (TGA) says.

The TGA encourages anyone who has concerns about this issue to speak with their healthcare professional.

“By informing physicians around the potential risk of skin cancer in Australia associated with this common treatment, we hope our findings can help improve the care of patients dealing with hypertension,” says Dr Daniels.