MONDAY, Aug. 6, 2012 (HealthDay News) -- A new study suggests several high blood pressure drugs, including Adalat, Nifediac and Cordipin, increase the risk of lip cancer in white people, possibly because the medications increase susceptibility to sun damage.
Lip cancer is very rare even among those who take the drugs, however, and the preliminary findings shouldn't convince patients to stop taking them, a researcher cautioned.
"They should be on the medication that's best for them," said study lead author Dr. Gary Friedman, an adjunct investigator with the Kaiser Permanente Medical Care Program of Northern California in Oakland. "It's really important to emphasize that this is a low-risk condition -- a rare cancer that's generally easily treated and not life-threatening."
Also, protection from the sun -- such as sunscreen and hats -- can ward off the sun damage that can lead to lip cancer, Friedman said.
Friedman and colleagues came across the possible connection while examining whether various medications had any links to higher rates of cancer.
The common high blood pressure drugs they examined were: hydrochlorothiazide (a diuretic known as HCTZ and the brand names Aquazide H, HydroDIURIL and Microzide); HCTZ combined with triamterene (known by the brand names Dyazide and Maxzide); the ACE inhibitor lisinopril (brand names Prinivil and Zestril); and the calcium channel blocker nifedipine (brand names Adalat, Nifediac, Cordipin, Nifedical, and Procardia).
For the study, scheduled for publication Aug. 7 in the journal Archives of Internal Medicine, the researchers used data on Kaiser Permanente health plan patients and compared more than 700 patients in northern California with lip cancer to nearly 23,000 people in a control group. They found that white people taking some of these drugs have about a four times greater risk of getting squamous cell lip cancer during a period five years, Friedman said. Risk appeared to increase with length of use. The normal risk is about 1 in 100,000, he said.
The increased risk persisted even when researchers accounted for smoking, which raises the risk of lip cancer. Overall, however, the disease is rare and mainly occurs in fair-skinned people who spend a lot of time in the sun, Friedman said.
The beta blocker atenolol (brand name Senormin or Tenormin), a blood pressure drug that doesn't increase susceptibility to sun damage, didn't appear to raise the risk of lip cancer. And the findings for lisinopril were weaker than those for HCTZ, HCTZ/triamterene and nifedipine.
Lip cancer, an oral cancer, rarely spreads and is usually easy to treat, Friedman said.
Millions of Americans take the drugs, said Dr. Gregg Fonarow, professor of medicine and director of the Ahmanson-UCLA Cardiomyopathy Center in Los Angeles.
Fonarow is skeptical of the study, which was funded by the U.S. National Cancer Institute. He said the findings conflict with previous research and may not reflect a cause-and-effect relationship between the medications and lip cancer.
"Further studies are needed," he said, "and these findings should be of no concern to patients receiving these medications."
For more about oral cancer, a category that includes lip cancer, try the U.S. National Library of Medicine.