Dec. 3, 1999 (New York) -- Do blood-pressure-lowering drugs (antihypertensive agents) cause cancer? Could they possibly prevent it? These issues were addressed here at a special session on cancer risks at the 14th Scientific Meeting of the American Society of Hypertension (ASH). Although one study found ACE inhibitors to be protective, another sparked controversy by linking diuretics to renal cell carcinoma (a form of kidney cancer).
Treatment with an ACE inhibitor not only can lower blood pressure and protect kidneys but also can significantly reduce one's risk of dying from cancer -- especially a woman's risk of death from breast or gynecologic cancers, according to John L. Reid, professor of medicine at the University of Glasgow in Scotland. Reid is the lead researcher for a study of 5,297 patients taking antihypertensive medications who were followed-up for 16 years.
Reid tells WebMD that recent studies suggest that some antihypertensive treatments are cancer-causing, but he disagrees with these findings. "The only cancer in which we have seen a slight increase in incidence [in patients taking antihypertensives] is renal cancer, and let me say that this is a very, very rare cancer," he says.
In the study, 1,559 patients with high blood pressure were treated with an ACE inhibitor, while the other patients were treated with a variety of other antihypertensive agents. Among the patients treated with ACE inhibitors, there were 60 cancers; there were 267 cancers among the patients taking other agents.
According to Reid, among the patients taking ACE inhibitors, the risk of death from cancer was a third less than the risk for patients never treated with an ACE inhibitor. Women taking ACE inhibitors had only half the risk of cancer-related death -- and only one-third the risk of dying from a sex-specific cancer such as breast or ovarian disease.
Reid says that there are several theories about why ACE inhibitors are protective against cancer, but "I think the most likely explanation is that angiotensin II [the body substance that ACE inhibitors block] is known to stimulate cells to divide -- so blocking that action is protective," he says. "Additionally, it blocks [blood vessel growth], thus reducing blood supply."
In contrast to Reid, Franz H. Messerli, MD, presented his analysis of multiple past research studies that suggests long-term diuretic use increases the risk of renal cell carcinoma, especially in middle-aged women. Messerli is medical director of the division of research at the Alton Ochsner Clinic in New Orleans.
Reid says, however, "In our much larger [study] database, we found no increased risk for treatment with diuretics."
Most of the audience of physicians attending the session criticized Messerli's finding, but Reid said that he agreed with Messerli's position that middle-aged women should not be routinely given diuretics. "I come to this conclusion for a different reason," Reid says. "I think these women have a low risk of a cardiovascular event, and I think that this population tends to be overtreated."
John H. Laragh -- master professor of medicine at New York Hospital-Cornell Medical Center -- tells WebMD, "I think that it is worth looking at these issues of antihypertensives and cancer, but further studies are needed, because the evidence is so preliminary and so weak that I wouldn't make any recommendations."
But -- illustrating the variety of medical opinion on these issues -- Laragh, who is a past president of the American Society of Hypertension and is director of the cardiovascular center at New York Hospital-Cornell Medical Center, says that he doesn't use long-term diuretic therapy because he thinks it puts patients at risk for salt depletion.