Study Shows Adherence to Oral Medications for Metastatic Breast Cancer Is Affected by Side Effects Cost Patient Knowledge and Care Team Supports

What you need to know

Investigators from John Theurer Cancer Center (JTCC) participated in the first study to evaluate factors that influence the ability of people with metastatic breast cancer to adhere to their prescribed regimen of oral anticancer medication. The researchers found that multiple factors affected adherence, including side effects, cost of the therapy, patients' knowledge about the medication, and communication with their care team. The study; Barriers and facilitators to taking CDK4/6 inhibitors among patients with metastatic breast cancer: A qualitative study, is being published in Breast Cancer Research and Treatment.

In the U.S., about 10% of breast cancers are diagnosed at the metastatic stage and 20-30% of early-stage breast cancer progress to metastasis. Prior research has investigated adherence to oral anticancer drugs among patients with early-stage breast cancer, but until now, no studies had been performed in people with metastatic disease. 

Enzyme inhibitors CDK4 and CDK6 (examples include palbociclib, ribociclib, and abemaciclib) have been shown to slow metastatic breast cancer progression and extend survival. Patients typically take them for as long as they remain effective, but these medications may have a high out-of-pocket cost and in some patients, cause side effects.

"This study shows that patients' ability to take their CDK4/6 inhibitor as prescribed can be influenced by their understanding of the medication and its use, the side effects they experience, support from the care team, and financial factors," explained Deena M. Atieh Graham, M.D., a medical oncologist at JTCC who co-authored the study. "Assessing these factors when a patient begins CDK4/6 inhibitor treatment and periodically thereafter can help us identify these issues earlier and address them sooner. Enhancing adherence to treatment could reduce healthcare costs and improve metastatic breast cancer outcomes."

What the Study Found

The study surveyed 25 patients with metastatic breast cancer, 9 of their caregivers, and 13 cancer care providers at two National Cancer Institute-designed Comprehensive Cancer Centers: Georgetown Lombardi in Washington, D.C., and Moffit Cancer Center in Tampa. Of note, the investigators found that:

• Patient adherence is high when they understand how the treatment works and believe it is effective, and decreases with poor patient understanding.
• Side effects could cause interruptions in taking the medication or reducing the dose, though patients generally felt side effects were not as bad as chemotherapy and were acceptable given the drug's effectiveness.
• Effective communication with the care team improved adherence to therapy, especially the assistance of nurses, pharmacists, and social workers.
• Cost could be a barrier to adherence, with medication refills sometimes delayed while waiting for insurance approval and financial assistance criteria creating a coverage gap for some patients in need.
• Family and friends often provide motivation for patients to take their medicine.

The researchers concluded that future studies should include larger groups of patients with metastatic breast cancer to inform the design of effective interventions to improve oral medication adherence.