Only approximately 49% of nearly 8800 patients with early stage breast cancer fully completed their prescribed regimen of hormone therapy, according to a study by Columbia University Medical Center in NewYork, New York.1 Younger women in particular were more likely to discontinue treatment, the study found, pointing to the need for scientists to better understand noncompliance and develop more effective interventions.

Physicians often prescribe up to 5 years of oral hormone therapy, including tamoxifen and aromatase inhibitors, to reduce the risk of cancer recurrence and death. However, some small previous studies have indicated that only 40–60% of women finish their recommended therapy.

Leader of the study Dawn Hershman, MD, associate professor of medicine and epidemiology at Columbia, decided to get a more comprehensive picture. She and colleagues examined 8769 women diagnosed with stage 1,11, or III hormone-sensitive breast cancers between 1996 and 2007. Forty-three percent of women used tamoxifen, 26% used aromatase inhibitors, and 30% used both.

Researchers found that women younger than age 40 years had the highest risk of stopping therapy—by 4.5 years, 32% had stopped. Of those who did not stop, only 72% finished on schedule—meaning they took their medication more than 80% of the time. Additionally, 13% of women delayed getting their first prescription refilled.

Women younger than age 40 years and older than age 75 years who had lumpectomy versus mastectomy were more likely to discontinue hormonal therapy early, as were those with other medical illnesses. Asian and Pacific Islanders, women with a history of prior chemotherapy, those who were married, and those with longer prescription refill intervals were more likely to complete 4.5 years of hormone therapy.

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Illustration 1. Younger women are more likely to stop taking hormone therapy for early stage breast cancer before completing the prescribed regimen.

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Dr. Hershman notes that physicians often are unaware of patient compliance and that the rate of noncompliance among patients younger than age 40 years is disturbing because this group has the longest life expectancy. Among possible reasons for noncompliance are: side effects of the therapy, such as joint pain, hot flashes, or fatigue; a lack of understanding of the benefit of the therapy; and the high costs of medications or insurance copayments.


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    Hershman DL, Kushi LH, Shao T, et al. Early discontinuation and nonadherence to adjuvant hormonal therapy in a cohort of 8,769 early-stage breast cancer patients. J Clin Oncol.. 2010; 28: 4120-4128.