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When older adults with cancer take multiple medications—including ordinary drugs like blood pressure pills, supplements, or antacids—it can result in more toxic chemotherapy side effects and even a need to stop cancer treatment, according to new research at the Wilmot Cancer Institute.

The latest study, published in the journal Cancer, provides a cautionary note to both patients and regarding "polypharmacy," a buzz word describing the concurrent use of multiple medications. It's extremely common, applying to nearly 92% of with cancer.

A key finding: Individuals who had one or more major potential drug interactions also had 59-percent-higher odds of having to stop earlier than recommended.

"It's possible that polypharmacy affects both the experience and the effectiveness of chemotherapy," said Erika Ramsdale, M.D., a Wilmot oncologist, geriatrics specialist, data scientist, and senior author of the paper.

Last year, Ramsdale and colleagues published a descriptive study that laid out the scope of the polypharmacy problem and categorized medication issues in a nationwide sample of 718 adults with a mean age of 77 who had stage 3 or 4 cancer and other .

In that first study, researchers showed that the majority of the patients had at least one other serious health concern, often cardiovascular disease. Other details included:

  • 70% were at risk of drug-drug interactions;
  • 67% were taking at least one drug that was potentially inappropriate;
  • 61% of the patients were taking five or more medications before starting chemotherapy;
  • and nearly 15% were taking 10 or more medications.

Both studies suggest that physicians should carefully screen for medication usage and possible drug interactions upon a new patient's diagnosis.

More information: Mostafa R. Mohamed et al, Association of polypharmacy and potential drug‐drug interactions with adverse treatment outcomes in older adults with advanced cancer, Cancer (2023). DOI: 10.1002/cncr.34642

Erika Ramsdale et al, Polypharmacy, Potentially Inappropriate Medications, and Drug-Drug Interactions in Vulnerable Older Adults With Advanced Cancer Initiating Cancer Treatment, The Oncologist (2022). DOI: 10.1093/oncolo/oyac053

Journal information: Cancer