Some drugs that treat high blood pressure may increase the risk of lip cancer, a new study suggests.
In the study, people who took the high blood pressure drug hydrochlorothiazide for five years or more were four times more likely to develop lip cancer, compared with those who did not take the drug. The study included only Caucasian people.
Hydrochlorothiazide is a photosensitizing drug, meaning it can increase a person's sensitivity to sunlight. People who take photosensitizing drugs may burn more easily, or develop rashes upon sunlight exposure. Previous studies have linked hydrochlorothiazide and an increased risk of certain skin cancers.
Other photosensitizing drugs examined in the study, including one called nifedipine, increased the risk of lip cancer more than twofold in whites.
The findings held even after the researchers took into account study participants' smoking, a factor that increases the risk of lip cancer.
Lip cancer is rare (there are about 0.7 cases per 100,000 people per year in the United States), and the benefits of high blood pressure drugs generally outweigh the increased risk of this particular cancer, the researchers said.
"However, physicians prescribing photosensitizing drugs should ascertain whether patients are at high risk of lip cancer because of their fair skin and long-term sun exposure, and discuss lip protection with them," the researchers said.
Ways to prevent lip cancer include wearing a hat with a sufficiently wide brim to shade the lips, and wearing lip sunscreens, the researchers said.
The findings are based on a study of 712 patients in Northern California diagnosed with lip cancer between 1994 and 2008, and nearly 23,000 people, of a similar age and gender and living in the same region, who did not have lip cancer.
The drug atenolol, which is prescribed for high blood pressure but is not photosensitizing, did not increase the risk of lip cancer. This suggests the condition of high blood pressure itself is not to blame for the link, the researchers said.
The researchers did not take into account how much time participants spent in the sun. However, it is not likely that participants who took photosensitizing high blood pressure drugs spent significantly more time in the sun compared with those who took atenolol, which was not found to increase lip cancer risk, the researchers said.
The study, conducted by researchers at the Kaiser Permanente Medical Care Program in Oakland, Calif., is published today (Sept. 10) in the journal Archives of Internal Medicine. It was published online Aug. 6.
Pass it on: Use of certain high blood pressure medications is linked to lip cancer risk.