Non-Adherence with Adjuvant Tamoxifen Therapy in Women with Early Stage Breast Cancer

Heather Jones, MD

University of Pennsylvania Cancer
Last Modified: May 12, 2001

Presenter: A. H. Partridge, P. S. Wang, E. P. Winer, J. L. Avorn
Affiliation: Dana-Farber Cancer Institute, Boston, MA; Brigham and Women's Hospital, Boston, MA


    Tamoxifen has been shown to help prevent breast cancer recurrence and death in women with early breast cancer. Yet, non-compliance for a number of reasons appears to be an issue. This study from the Dana?Farber Institute attempts to quantify the level of non-adherence with tamoxifen in a sample of women who have just started adjuvant therapy with this hormonal therapy.

Materials and Methods:

  • This study included all filled prescriptions among continuously enrolled patients in New Jersey's Medicaid and Pharmaceutical Assistance to the Aged and Disabled programs who filled a first prescription for tamoxifen from 1990-1996 (N = 2356).
  • The number of "days covered" by filled tamoxifen prescriptions in the 365-day period following initiation of therapy was calculated, and patients' demographic and clinical characteristics were assessed.

    The outcome measures were:

    1. The proportion of days during the study year for which patients had filled prescriptions for tamoxifen
    2. predictors of good vs. poor adherence.


  • Patients filled prescriptions for tamoxifen for a mean of 77% of days in the study year.
  • 30% of patients had fewer than 80% of days with drug available during the year.
  • Multivariable analysis indicated that patients at the extremes of age (=45 and =85 years), and nonwhite patients had significantly lower rates of adherence, after adjusting for possible confounders.
  • After excluding patients with an identifiable reason for possible therapeutic discontinuation of tamoxifen during the study year, predictors and overall adherence did not change substantially.
  • 46% of patients on tamoxifen did not see an oncologist.

Authors' Conclusions

  • The mean level of adherence to tamoxifen during the first year of therapy is higher than rates seen with other chronic oral medications, but nearly a third of patients may be at risk for inadequate clinical response because of poor adherence.
  • Such poor adherence cannot be predicted using demographic or clinical data, with the exception of age and race.
  • Further efforts are necessary to document and prevent suboptimal adherence, particularly in younger, older, and non-white populations.

Clinical/Scientific Implications:

    It is important to note that it is difficult to tease out recurrence rates and toxicity data from population studies. Thus, some of the non-adherence seen in this study may be due to oncologist discontinuing tamoxifen and not patient non-compliance. While cancer patients adhere to chronic use of oral medications better than their non-cancer counter parts, there is room for improvement.

OncoLink ASCO 2001 coverage is provided by an unrestricted educational grant from Amgen