Zhensheng Wang, a postdoctoral researcher at the Dan L. Duncan Comprehensive Cancer Center at Baylor College of Medicine in Houston, TX, along with his colleagues, set out to examine the effects of a class of drugs called calcium channel blockers (CCBs) on the risk of pancreatic cancer.
CCBs are used to stop calcium from entering the heart's muscle cells, which, in turn, relaxes the blood vessels.
This relaxation makes them useful drugs for the treatment of hypertension.
Previous studies, the authors of the new research explain, have shown that antihypertensive medication increases levels of a receptor called soluble receptor for advanced glycation end-product (sRAGE).
Blood pressure drugs, on the other hand, raise sRAGE levels, so the authors started out with the hypothesis that, on the contrary, antihypertensive medication would lower the risk of pancreatic cancer.
But the results of the study surprised the researchers. The findings were presented at the American Association for Cancer Research Annual Meeting, which took place in Chicago, IL.
CCBs may double pancreatic cancer risk
Wang and colleagues examined the data on 145,551 postmenopausal women aged between 50 and 79 who were registered in the Women's Health Initiative (WHI) — a large, long-term study spanning more than 20 years.
In addition to CCBs, three other types of blood pressure drugs were included in the analysis: beta-blockers, diuretics, and angiotensin-converting enzyme inhibitors.
The researchers looked at women who were enrolled in the WHI study between 1993 and 1998, and they followed them until 2014.
During this period, 841 cases of pancreatic cancer were recorded. Wang and colleagues measured the sRAGE serum levels of 489 of these women, and those of 977 women who did not develop the condition.
The researchers used statistical models to examine the link between the four types of blood pressure medication and pancreatic cancer risk.
The analysis revealed that women who had ever taken short-acting CCBs were 66 percent more likely to develop pancreatic cancer; women who had taken CCBs for 3 or more years were more than twice as likely to have pancreatic cancer than women who had taken other blood pressure drugs.
Additionally, women who had used short-acting CCBs had considerably lower sRAGE levels than those who took other blood pressure drugs.
None of the other blood pressure drugs were linked with an increased risk of pancreatic cancer.
What explains the link?
This was just an observational study, but the researchers have a few clues regarding the potential mechanisms that may explain the findings.
"[T]he blockage of the calcium channel caused by [the] use of CCBs may potentially reduce sRAGE release," Wang explains, "and thus further decrease the levels of anti-inflammatory sRAGE."
"This is important as chronic inflammation is a well-recognized risk factor for pancreatic as well as many other cancers," he adds.
Also, as Wang explains, "hypertension, [...] is one of the components of metabolic syndrome, and metabolic syndrome is a possible risk factor for pancreatic cancer."
These links may explain why "[p]ancreatic cancer typically occurs in elderly individuals who also have chronic comorbid medical conditions, such as hypertension," Wang suggests.
Findings 'of great public health significance'
"Pancreatic cancer is the fourth leading cause of cancer-related mortality in the United States," Wang says.
According to the National Cancer Institute (NCI), over 55,000 people will have been diagnosed with pancreatic cancer in 2018, and only 8.5 percent of these will survive for 5 years.
"Antihypertensive medication use has increased significantly; therefore, it is of great public health significance to address the potential association between antihypertensive medication use and risk of pancreatic cancer in the general population."