Full course of AI keeps disease at bay longer

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Actual adherence rates may be lower

It should be noted that all of the patients in this clinical trial had the medications provided to them and agreed to be participants in a randomized clinical treatment trial. Therefore, the rate of nonpersistence and noncompliance may underestimate the rates in the general population, where behavior, access, and financial factors may have a larger effect. In a prior study by our group, we found that higher copayment amounts were inversely associated with adherence to adjuvant AI therapy. Others have found a similar association with imatinib in patients with chronic myeloid leukemia. The introduction of generic aromatase inhibitors has also resulted in decreased discontinuation and increased adherence to hormonal therapy. These studies and others suggest that medication compliance may be improved if financial barriers are removed. Therefore, public policy efforts are needed to assure access to curative therapies.

Dr. Dawn L. Hershman of Herbert Irving Comprehensive Cancer Center and Columbia University Medical Center, New York, made this comments in an editorial accompanying the study by Chirgwin et al. (J Clin Oncol. 2016 May 23. doi: 10.1200/JCO.2016.67.7336).




It’s common sense that adherence to a therapy with proven efficacy can result in better outcomes, and now there’s good scientific evidence to back it up.

A retrospective study of patients enrolled in a seminal clinical trial shows that postmenopausal women with early hormone receptor–positive breast cancer who stopped taking the aromatase inhibitor letrozole (Femara) before 5 years were up had an approximately 50% reduction in disease-free survival (DFS) compared with women who took the drug as prescribed, reported Dr. Jacquie H. Chirgwin of the Maroondah Breast Clinic in Ringwood East, Victoria, Australia, and colleagues (J Clin Oncol. 2016 May 23 doi: 10.1200/JCO.2015.63.8619).

“These results reinforce the importance of optimizing adherence by educating and supporting patients about the prognostic importance of adherence, the possible [adverse events] associated with switching treatment, and effective toxicity management,” they said.

The authors looked at data on 6,144 women who took part in the Breast International Group 1-98 (BIG 1-98) trial, which showed that 5 years of letrozole was associated with better overall survival (OS) than 5 years of tamoxifen, that sequential tamoxifen and letrozole were adequate for intermediate-risk patients, and that 5 years of either drug or a sequence were equally effective for low-risk patients.

To see whether shorter duration of therapy or less-than-ideal adherence to dosing had an adverse effect on outcomes, the investigators conducted regression analyses examining the relationship between DFS and both persistence (duration) of therapy, and compliance (adherence to dose and regularity of dosing).

They found that early cessation of letrozole was associated with a multivariable model hazard ratio (HR) for DFS of 1.45 (P = .01) and that a compliance score of less than 90% was associated with an HR of 1.61 (P = .02).

About 20% of women who took sequential therapy were nonpersistent, compared with 16.9% of women who took tamoxifen, and 17.6% of those who took letrozole.

In the large majority of cases (82.7%) adverse events were the primary reason for early discontinuation of therapy.

Patients who were older, smoked, had node-negative disease or had a prior thromboembolic event were less likely to be adherent, the investigators found.

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