Many patients older than 65 years with localized breast cancer are eligible for adjuvant hormonal therapy, but little is known about why patients start and stop treatment. Frailty may influence decisions about starting and stopping hormonal treatment.

A new study found that most women adhered to their oncologists’ recommendations to treat their estrogen-positive breast cancer with hormone therapy (either an aromatase inhibitor or tamoxifen). These drugs prevent tumors from using estrogen to fuel growth.

“Women 65 years of age and older comprise about half of patients with breast cancer. Some studies have suggested that this group initiates therapy less often and discontinues treatment more frequently than younger or middle aged women,” said Vanessa B. Sheppard, PhD, associate professor of oncology and assistant director of health disparities research at Georgetown Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC.

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“We found a more positive picture of use—although more than half of patients stopped hormonal therapy before completing the full 5 years of recommended treatment, only 14% failed to start treatment,” she said. “This is reassuring, as it’s important for women to give themselves a chance for the best outcome possible, regardless of their age.”

The 7-year study was conducted at 78 institutions and clinics in the United States, and enrolled 1,062 women age 65 to 91 years with locally invasive cancer that had not metastasized. Women in the study were grouped as pre-frail, frail, or robust using a previously validated 35-item scale. Most of the study participants (76.4%) were robust.  

Women in the pre-frail or frail groups were more likely to not start hormonal therapy. However, frailty was not associated with early discontinuation of hormonal therapy. This group may be justified in not starting treatment for their breast cancer compared with women who are more robust.

“It may be that these women, with the concurrence of their physicians, felt they would not live long enough to benefit from the therapy given competing health conditions, and they may have wanted to avoid any toxicity from treatment,” Sheppard said.

Researchers found that the overall discontinuation rate (stopping treatment before completing the full 5 years) was 51.5%. The risk of discontinuation was higher with increasing age and lower for advanced stages of the disease. This rate of discontinuation is about the same as that seen in other studies.

This study was published in the Journal of Clinical Oncology (doi:10.1200/JCO.2013.51.7367).