Among older women with estrogen receptor (ER)-positive ductal carcinoma in situ (DCIS), initiation and adherence levels for adjuvant tamoxifen or aromatase inhibitors are low, according to a study published in the journal Cancer.1

The National Surgical Adjuvant Breast and Bowel Project B35 and International Breast Cancer Intervention Studies II Ductal Carcinoma In Situ trials have demonstrated similar reductions in recurrence risk among patients with DCIS treated with anastrazole and tamoxifen. Although studies have shown low levels of hormone therapy drug initiation among these patients, there are limited data examining 5-year adherence rates for these drugs.

To evaluate both initiation and adherence levels, researchers analyzed data from 2871 women with ER-positive DCIS diagnosed between 2007 and 2011 and included in the Surveillance, Epidemiology, and End Results (SEER) and Texas Cancer Registry databases. Of those, 45% began treatment with tamoxifen or an aromatase inhibitor such as anastrazole within 1 year of cancer diagnosis.

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Results showed that women age 66 to 70 years who underwent lumpectomy and radiotherapy were significantly more likely to initiate hormonal therapy.

Treatment initiation was also significantly associated with geographic location, education, marital status, diagnosis year, and race/ethnicity.

Researchers also found that adherence to hormonal therapy decreased from 67% during the first year to 30% in the fifth year, demonstrating low levels of adherence in this population.

The findings suggest that further studies are needed to develop strategies to ensure that informed discussions regarding hormonal therapy for preventing cancer recurrence are occurring between clinicians and patients.


1. Zhao H, Hei N, Wu Y, et al. Initiation of and adherence to tamoxifen and aromatase inhibitor therapy among elderly women with ductal carcinoma in situ. Cancer. 2016 Oct 25. doi: 10.1002/cncr.30425. [Epub ahead of print]