A large international study of more than 23,000 patients has found that common medicines used to treat high blood pressure and cholesterol, as well as heartburn, may be impacting cancer treatment effectiveness.
Researchers from the University of South Australia (UniSA) were looking at whether everyday drugs used to treat chronic health conditions could potentially affect treatment for breast cancer, and what they found was a “concerning” pattern when it came to certain medications.
Anaylzing data from 19 breast cancer clinical trials, featuring 23,211 patients, the researchers discovered that one class of drug in particular – proton-pump inhibitors (PPIs), used to treat indigestion and heartburn – was associated with poorer overall survival, progression-free survival and a 36% increased risk of serious adverse events during treatment.
“Many women with breast cancer are also managing other chronic conditions such as high blood pressure, diabetes or acid reflux, meaning they are often taking multiple drugs at once,” said lead author Dr Natansh Modi, from UniSA and Flinders University. “Our results don’t suggest that people should stop taking their non-cancer medicines, but it underlines how important it is for doctors to regularly review patient medications because people are living longer and managing multiple health issues.”
The researchers believe that PPIs might have the potential to interfere with immune system responses or even change how cancer therapeutics are absorbed into the body and metabolized. However, these processes are not yet well understood.
The team also identified a link between taking beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers and calcium-channel blockers – all drugs commonly used to treat heart disease or hypertension – and higher rates of severe negative side-effects. However, there was no connection between these medications and overall survival.
Meanwhile, cholesterol-managing statins and the type 2 diabetes drug metformin had no meaningful impact on survival or side-effects from treatment. In a 2021 study, researchers found that statins were associated with positive outcomes in patients with breast cancer.
While more research is needed, this study – thought to be the largest of its kind – has flagged the need for further investigation into PPIs and the role they might play in breast cancer treatment.
“It doesn’t mean that patients should cease their reflux medication without medical advice, but clinicians should be alert to potential risks and review whether PPIs are genuinely needed,” said corresponding senior author Ashley Hopkins, an associate professor at Flinders University.
Following on from their findings, the researchers are calling for a closer look into the potential biological mechanisms driving these adverse cancer treatment outcomes – and for patients and clinicians to be aware of possible interactions.
The research was published in the journal Cancer Medicine.
Source: University of South Australia
