The benefits obtained with antihypertensive medications in colorectal cancer may indicate potential mechanisms that act against tumor cells.
Blood pressure medications may improve survival in patients with colorectal cancer, highlighting the potential for low-cost drugs to provide additional benefits beyond hypertension treatment.
“Sometimes we forget the importance of adherence to prescribed pharmacological treatments in life-threatening conditions like cancer,” said Rajesh Balkrishnan, who holds a PhD in public health and is a professor of public health sciences at University of Virginia School of Medicine in Charlottesville, in an interview with CURE®. “Clearly these studies are showing that medication adherence is important across all conditions, whether life-threatening or not.”
To assess the potential benefit of antihypertensive medications in patients with colorectal cancer, Balkrishnan and colleagues analyzed data from 13,982 patients ages 65 and older with stage 1 through 3 disease.
Regarding the exclusion of patients with stage 4 colorectal cancer, Balkrishnan noted, “Right now, the prognosis of patients with late-stage colorectal cancer is quite poor. Most of the current treatment guidelines have moved those patients towards palliative care. Aggressive treatment approaches like colon resection and radiation are reserved for patients in stages 1 to 3.”
He added that the patients in this study represent a unique group.
“These are patients who essentially were diagnosed with hypertension after they were diagnosed with colorectal cancer,” Balkrishnan said.
Most patients in the study were taking some form of blood pressure medications, with 2,553 patients not taking drugs for hypertension regularly.
“We compared patients who were using these agents like thiazide diuretics and ACE inhibitors, which have potential mechanisms of acting against tumor cells,” Balkrishnan mentioned.
Follow-up started one year after patients started taking blood pressure medications, during which researchers determined that patients taking antihypertensive drugs had a lower risk for cancer-specific mortality. A decreased risk for mortality was specifically demonstrated in patients taking ACE inhibitors, beta-blockers, and thiazide diuretics. In addition, patients who adhered to anti-hypertensive medications had a lower risk for cancer-specific mortality compared with those who did not adhere to the regimen.
“There's some mechanism going on here between the use of these (antihypertensive) agents and better outcomes related to colorectal cancer,” Balkrishnan said. “Our findings are still very preliminary. We have to study the entire GI tract. We only looked at colorectal (cancer), but we need to look at gastric (cancers). We need to separate out the colon, rectum, look at the intestinal cancers. And then these findings have to be confirmed by a larger clinical trial. But there seems to be protective effects of these agents related to colorectal cancer.”
Balkrishnan mentioned that more research, particularly clinical trials, is also needed to see whether antihypertensive medications can also benefit patients without hypertension.
The benefits from antihypertensive medications in patients with colorectal cancer may be greater than those observed in other agents, Balkrishnan noted.
“This is sort of promising because the type of benefits we see, … they seem more pronounced than the benefits we see with some of these newer immune-oncological agents,” he added. “So you have one (cancer therapy) agent, which costs upwards of hundreds of thousands of dollars a year, and one group of drugs which have been used for several decades are known to be safe and effective, and just cost patients $4 to $5 a month. We have a more cost-effective option for improving survival and quality of life in colorectal cancer patients.”
Another major takeaway from this study is the importance of medication adherence.
“Many of the patients who are detected with cancer in our country are most likely to have other coexisting conditions like hypertension and diabetes,” Balkrishnan concluded. “And many of these agents that we study — for example, with hypertension or metformin for diabetes — have shown in preliminary studies to have some effects on the tumor vasculature. I think it becomes really important to stress the importance of adherence to these treatments in patients who have these conditions because there's nothing to lose and everything to gain with these patients.”
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