With an estimated 70% of all cancers in the USA being diagnosed in older adults by 2030, more and more elderly cancer patients will encounter multiple medication use (polypharmacy) increasing the risk of adverse drug reactions and drug interactions.

Authors call for greater recognition of this growing health-care issue and propose some practical solutions to guard against polypharmacy including incorporating drug discontinuation into the prescribing process as standard practice, and issuing guidelines on the management and reduction of multiple medication use in the outpatient setting where most patients with cancer are treated.

"The people most at risk from polypharmacy are those who see several doctors, have prescriptions dispensed at several pharmacies, have concurrent comorbidities, and are elderly", explain Judith Lees from Royal Adelaide Hospital Cancer Centre, Adelaide, Australia and Alexandre Chan from the National University of Singapore and National Cancer Centre, Singapore.

Research suggests that polypharmacy is becoming more frequent in older people because an increasing number of drugs are being used to prevent or treat an increasing number of medical problems in the aging population.

A UK study found that elderly cancer patients were taking an average of seven medications, while a Canadian study reported that nearly all newly diagnosed elderly patients were taking an average of five prescribed drugs even before the start of cancer treatment. Furthermore, complementary and alternative medicines (CAMs), such as herbal remedies and supplements, are becoming increasingly popular among cancer patients, including the elderly.

Taking several medications at the same time increases the likelihood of adverse drug reactions and drug interactions that can alter efficacy, increase toxic effects and hospitalisations, and substantially raise health-care costs.

A Canadian study reported that half of elderly patients experienced side-effects from the preventative medications they were taking including antihypertensives and anticoagulants despite having advanced cancer. A recent systematic review found that up to a third of outpatients were exposed to potential drug-drug interactions, most commonly warfarin and anti-epileptics.

According to the authors, the key challenges for medical teams are the identification of what drugs are being taken (eg, prescribed, over-the-counter, CAMs) and preventing or managing any adverse effects or drug interactions.

Although many drug interactions are well-documented their identification becomes increasingly difficult when patients are taking many medications. Often no safety profile exists for the various combinations of medications a patient newly diagnosed with cancer might already be taking and the proposed multidrug chemotherapy regimen.

The authors suggest: "A technique for investigation of drug reactions specifically in patients receiving chemotherapy might prove a practical solution, especially in elderly patients on more than one medication."

Key recommendations include the need for a routine review of all medications when elderly patients are first diagnosed with cancer before prescribing anticancer drugs, and for the "rational discontinuation" of drugs to be included as part of a comprehensive geriatric assessment of all elderly patients who are newly diagnosed with cancer.

"The ideal comprehensive medication history includes an interview that has questions about over-the-counter and CAMs, inspection of drug containers or lists, or both, and contact with community pharmacies or family doctors...Although a framework of incorporation of drug discontinuation into the prescribing process has been proposed, it is not yet standard practice", say the authors.

Other practical interventions discussed in the paper include a geriatric multidisciplinary team to prescribe the best drugs, the involvement of pharmacists to discuss patients' medications, improved training in the unique needs of geriatric patients, and computerised decision support such as drug interaction alerts with computerised prescribing and dispensing to reduce adverse events.

Source: The Lancet