Study Reports 25% of Women Don't Complete Recommended Breast Cancer Treatment

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One-quarter of women who should take hormone-blocking therapies as part of their breast cancer treatment either do not start or do not complete the 5-year course, according to a new study led by University of Michigan Comprehensive Cancer Center researchers.

For many women with hormone receptor--positive breast cancer 5 years of daily tamoxifen or an aromatase inhibitor is recommended to reduce cancer recurrence and increase survival. Recent studies suggest there may be even more benefit for some women to continue this treatment for 10 years.

A recent study of 743 women eligible for endocrine therapy found that about 11% of the study participants never initiated the tamoxifen or aromatase inhibitor therapy and 15% stopped taking treatment early. Results were published online in Breast Cancer Research and Treatment. 1

“We’re doing well with women taking endocrine therapy, but there’s work to do,” says lead study author
Christopher Friese, PhD, RN, Assistant Professor at the University of Michigan School of Nursing. “If guidelines begin to shift so that some women at high risk of breast cancer recurring need 10 years of endocrine therapy, then the number of women who persist with treatment will likely worsen. We need to develop better ways of supporting women through this therapy.”

Side Effects A Major Deterrent

The most common reason patients said they either discontinued or never started endocrine therapy was side effects. Many women experience menopause-like symptoms such as hot flashes or vaginal dryness, and both types of drugs, more commonly the aromatase inhibitors, can cause joint pains.

The study surveyed women in the Detroit and Los Angeles areas who were diagnosed with breast cancer and reported to Surveillance, Epidemiology and End Results tumor registries. Women were surveyed at about 9 months after their diagnosis and again about 4 years later with questions about their use of tamoxifen or any type of aromatase inhibitor.

Women who expressed more worry about their cancer recurring were more likely to complete endocrine therapy, as were women who already took medication regularly.

Women who reported receiving less information about endocrine therapy were less likely to begin taking it, suggesting that doctors need to address patient education before treatment starts. Women who saw a breast surgeon as their primary follow-up, rather than a medical oncologist, were also less likely to begin endocrine therapy.

“It was particularly interesting that greater fear of recurrence was associated in our patient sample with greater adherence to endocrine therapy,” says senior study author Jennifer J. Griggs, MD, MPH, Professor of Internal Medicine at the University of Michigan Medical School and a medical oncologist who sees patients with breast cancer at the University of Michigan Comprehensive Cancer Center.

“We don’t want our patients living under a cloud of fear, so we need to develop creative ways to both reassure and motivate them. This means providing better education about the importance of staying on these medications and partnering with primary care and cancer doctors to help patients manage symptoms,” Dr. Griggs said. ■

Disclosure: The study was funded by National Cancer Institute grants R01 CA109696, R01 CA088370, K05 CA111340; National Institute for Nursing Research grant R00 NR01570; American Cancer Society. The authors reported no potential conflicts of interest.


1. Friese CR, Pini TM, Li Y, et al: Adjuvant endocrine therapy initiation and persistence in a diverse sample of patients with breast cancer. Breast Cancer Res Treat 138(3): 931-939, 2013.