If you’re among the 35 percent of adults in North Carolina who were told by a health professional that you have hypertension, chances are you’ve been prescribed blood pressure medication. An October 2018 study published in the British Medical Journal now links certain blood pressure drugs with an increased risk of lung cancer.
Angiotensin-converting enzyme (ACE) inhibitors are a group of widely prescribed blood pressure medications that are used to treat a variety of health problems with few serious side effects. After the study linking ACE inhibitors with lung cancer made headlines, Dr. Nagesh Jayaram, a medical oncologist at Southeastern Medical Oncology in Jacksonville, said some of his patients have expressed their concern.
“I’ve been hearing from some of my patients you know this question on whether I should be switching my blood pressure medication or should I stop taking my blood medication totally.”
The observational study wanted to examine whether ACE inhibitors could increase the risk of lung cancer, compared to a different group of blood pressure medications called angiotensin receptor blockers (ARBs). A team of researchers, led by Laurent Azoulay, associate professor of epidemiology and oncology at McGill University in Montreal, analyzed UK primary care records for nearly one million patients who started taking a new antihypertensive drug between 1995 and 2015. According to the study, ACE inhibitors were associated with an overall 14% increased risk of lung cancer, after considering factors that could influence their findings, including smoking, age, weight, and sex. Jayaram said the study’s findings are concerning, but considering the true relative lung cancer risk to an individual, the difference between ACE inhibitors and ARBs was slight.
“When they’re actually talking about the number of cases, the cases were the difference of 1.2 cases per 1000 versus 1.6 cases per 1000. It’s not even a whole case percentage point increase,” Jayaram said.
The study found lung cancer risk for patients who used ACE inhibitors for five years increased 22 percent compared to those who took ARBs. The risk was increased to more than 30 percent for patients who used ACE inhibitors for a decade or more. The study suggests this is likely caused by a buildup of a protein-like chemical called bradykinin. Dr. Paul Bolin, professor, and chair of the Department of Internal Medicine at the Brody School of Medicine in Greenville says bradykinin has been known to stimulate the growth of lung cancer cells.
“If you have a causal path and you double the exposure going from five to ten years; this is one of the parts of the study that concerns me, in that we need to listen to this data and look at it further. There’s physiology behind their findings. If we had seen a risk at five years but not at 10 years, that wouldn’t have made sense. But [since] there’s a progression over time, it’s more concerning.”
Even though the study suggests ACE inhibitors are more likely to cause lung cancer than ARBs, Bolin believes a side effect of the medication may have influenced the study’s findings.
“I think one of the things they spoke to in this trial that was very important is that ACE inhibitors cause coughs. And so anytime somebody has a cough, you sometimes you eventually get a chest x-ray. And we find things incidentally that we would have not found before. So there may be some other reasons behind why there was an increase in the detection of lung cancer.”
According to the British Medical Journal, ”this is the largest study to assess this specific association, and findings remained consistent after further analyses to test the strength of the results.”
Associate clinical professor at Brody School of Medicine Dr. Clint Parker said he hopes the study opens the door for more research examining how socioeconomic status, family history, diet, and other factors influence results. At this time, he said he’s not changing the way he prescribes blood pressure medication.
“In medicine, you’re always having to weigh risks versus benefits, that’s just part of the gig. So certainly, in the back of my mind, it’s provocative, and I think there needs to be more exploration of this association. But at this point, I don’t think the evidence kind of raises to a point where I would take definitive action and start taking people off of these medicines.”
Without medications like ACE inhibitors, people with high blood pressure face an increased risk heart attack, stroke or kidney failure. Even though the study suggests only a small percentage of people taking ACE inhibitors will eventually develop lung cancer, the numbers are important because of the abundant use of the medications worldwide.
“You’ve got to pay attention; we have to pay attention to this study,” Bolin said. “Now, does that mean we need to go out and tell everyone to come off ACE inhibitors, absolutely not.”