Why Some Women Don't Follow Up on Breast-Cancer Therapy

By Jane Farrell

Researchers have found that patients who did not adhere to their medication schedule for chronic conditions, such as diabetes, prior to a breast cancer diagnosis were twice as likely to skip oral adjuvant hormonal therapy after their diagnosis.

Patients who skipped medications for their chronic conditions had a 23 percent non-adherence rate to hormone treatment, compared with 10 percent for those who took one or more drugs for their conditions prior to a breast cancer diagnosis.

Other factors included the patient’s financial status and the cost of drugs.

The study, by researchers at Columbia University’s Mailman School of Public Health, Columbia University Medical Center, and NewYork-Presbyterian, is among the first to associate prior medication adherence patterns and subsequent adherence for breast cancer drug therapy. The findings were published in JAMA Oncology.

This large population-based study was based on data from the Truven Health Analytics MarketScan, a medical and pharmacy insurance claims database. The researchers identified 21,255 women 18 years or older who were diagnosed with breast cancer in 2010-2012 and had filled two or more prescriptions for tamoxifen and/or an aromatase inhibitor. Overall, 16 percent were non-adherent to their hormone replacement therapy.

“Given the fact that medications used in oncology are potentially life-saving or life-prolonging, it is surprising that non-adherence to these medications is common,” said Alfred I. Neugut, MD, PhD, Myron M. Studner Professor of Cancer Research and Professor of Epidemiology at the Mailman School of Public Health and lead author of the study.

Age had a strong association with adherence versus non-adherence. Compared to women with breast cancer between the ages of 55 and 64, women younger than 45 years and those between the ages of 45 to 54 were more likely to be less adherent, as were those 75 years of age or older. Women who were African-American, being treated by a specialist other than a medical oncologist, as well as those who had poor belief in the treatment’s efficacy, lower financial resources, and higher co-payments for the drug, were also less likely to adhere to the treatment. As the 30-day out-of-pocket costs rose from $5, there was a gradual increase in non-adherence.

Having a greater number of chronic conditions and a history of non-adherence to chronic medications in the year prior to a patient’s breast cancer diagnosis—regardless of the number of medications a woman was taking—was also associated with not taking the medications. “This finding revealed that those who are non-adherent to chronic medications are at increased risk for non-adherence to hormone therapy and could benefit from vigilance and possible future interventions,” noted Neugut.

Of the women studied, 62 percent initially used aromatase inhibitors, while 38 percent started with tamoxifen. Almost two-thirds (63 percent) used at least one prior medication for a chronic condition. These included common drugs for six chronic conditions: diabetes, hypertension, hyperlipidemia, thyroid disease, osteoporosis, and gastroesophageal reflux disease (GERD). The average rates of non-adherence in the year prior to the hormone therapy were substantial: 37 percent for diabetes; 28 percent, hypertension; 30 percent, hyperlipidemia; 21 percent, thyroid disease; 32 percent, osteoporosis; and 38 percent, gastroesophageal reflux disease.

“Non-adherence to hormone therapy for breast cancer can have significant impact on survival outcomes,” said Neugut, who is also co-director of the Cancer Prevention Program at NewYork-Presbyterian. “The hope is that by identifying patients at highest risk for non-adherence and having a detailed history of medication use, interventions can be developed and targeted at higher-risk groups.”