P5-17-05: 24 Months Follow-Up Results from PACT (Patient's Anastrozole Compliance to Therapy Programme), a Non-Interventional Study Evaluating the Influence of a Standardized Information Service on Compliance in Postmenopausal Women with Early Breast Cancer.
Authors: Lueck H-J , Hadji P , Harbeck N , Jackisch C , Blettner M , Zaun S , Windemuth-Kieselbach C , Beck T , Kbhler U , Schmitt D , Kreienberg R 
Published: June 2012

Introduction: According to recent retrospective studies, compliance to adjuvant endocrine therapy for early breast cancer (EBC) may drop to below 70% after one year and to as low as 50% by year 4. PACT aimed to increase treatment adherence in postmenopausal women taking an adjuvant aromatase inhibitor via a standardized information service (educational arm). Yet, after 12 months, there was no difference in compliance between the standard and educational arm (reported at this meeting 2010).

Methods: PACT is a prospective, randomised, two-arm parallel-group study in Germany, sponsored by AstraZeneca (NCT00555867). Postmenopausal women on anastrozole for hormone-receptor positive (HR+) EBC were randomized to routine clinical care alone or to receive additional standardized information (educational arm) at nine times over the first 12 months of adjuvant therapy. Primary endpoints were compliance and persistence rates in the educational versus routine arm after 12 months. Secondary endpoints included longer follow-up, reasons for non-compliance, influence of baseline characteristics, and clinical outcome parameters (DSF, OS). Compliance was evaluated via patient questionnaires, prescription data and physician recall. Per protocol compliance was analysed only for patients with full documentation both by patients and physicians. Persistence was defined as the duration of time from initiation to discontinuation of therapy (Cramer et al 2007) and measured by prescription data.

Results: PACT enrolled 4,923 female patients at 109 breast centres and 1,361 registered specialist practices from all regions in Germany. 4,397 patients were evaluable for baseline characteristics. 2,707 patients were evaluable for the primary endpoint (full documentation on tablet intake both by patients and physicians). No difference in compliance could be shown between the standard (88.2%) and the educational arm (88.3%) at 12 months (p=0.92, Fisher's exact test). Persistence rates were 40.3% for the standard arm and 43.0% for the educational arm, respectively (p=0.17, Fisher's exact test). At 24 months, data from 1539 patients was available for analysis compliance per protocol. Compliance rates were 88.7% (educational arm) and 87% (standard arm; p=0.29). Persistence again much lower at 41.1% and 42.1% (p=0.68). Variables influencing compliance were regular attendance to follow-up visits, participation in a cancer rehabilitation program, number of co-morbidities and current employment status. Persistence was influenced by factors such as tumour stage, joint pain and cancer rehab program participation.

Conclusion: The addition of standardized information materials to standard clinical care did not lead to a significant increase in compliance or persistence rates at 12 or 24 months. With 4,923 women included, the PACT study represents the largest prospective study to evaluate the influence of educational material as well as baseline demographic and histopathological characteristics on the compliance and persistence to adjuvant endocrine therapy in postmenopausal patients with HR+ EBC.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-17-05.