Background

ET represents a cornerstone in the treatment of early and late hormone receptors-positive (HR+) BC. However, adherence to ET is a major issue that can substantially impact survival outcomes. We explored whether PDDI with ET impact adherence.

Methods

We scanned the French version of the THIN™ database for women who had a reported diagnosis of BC and received ET (tamoxifen [tam] or aromatase inhibitor [AI]) between 1994 and 2021. Adherence was measured annually and defined by a medication possession ratio (MPR) ≥ 80% over 1-year prescription period. PDDI was classified using the Claude Bernard Drug Database into absent, minor (combination to take into account), moderate (combination requiring precautions for use), major (combination not recommended) and contraindicated. We used repeated-measure regression models to estimate odds ratios (OR) for the correlation between MPR ≥ 80% and age, baseline comorbidities, PDDI, and MPR during the previous year. Among patients with multiple PDDI, the worse PDDI category by patient was retained and included in the multivariable model.

Results

Among the 10,863 eligible pts, polypharmacy ≥ 5 drugs was reported in 33.7% and 47.8% of the tam and AI cohorts. PDDI occurrence is summarized in the table. PDDI were mostly moderate in the tam (60.4-80.6%) and AI (94.7%-99.3%) cohorts; contraindicated combinations were below 1%. In the tam cohort, annual MPR ≥ 80% was 79.3% (n = 2,824) at year 1 and 89.5% (n = 426) at year 5. The association between MPR ≥ 80% and presence of PDDI was not statistically significant neither in the tam (OR 0.991, 95% CI 0.0.914-1.075) nor AI (OR 1.046, 95% CI 0.954-1.147) cohorts. Table: 225P

Prevalence of PDDI with ET at baseline and during follow up

Conclusions

Adherence to ET was not associated with PDDI in patients with HR+ BC treated with tam or AI.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

A. Bardet: Financial Interests, Personal, Other: Roche SAS. O. Bougacha, L. Gantzer, B. Lekens: Financial Interests, Full or part-time Employment: Cegedim R&D. I.V. Luis: Financial Interests, Institutional, Invited Speaker: Amgen; Financial Interests, Institutional, Invited Speaker: Pfizer/Edimark; Financial Interests, Institutional, Invited Speaker: Pfizer/Edimark; Financial Interests, Institutional, Invited Speaker: AstraZeneca. S. Delaloge: Financial Interests, Institutional, Advisory Board: AstraZeneca, Novartis, Pierre Fabre, Orion, Sanofi, Rappta, Cellectis, Isis/Servier; Financial Interests, Institutional, Invited Speaker: Exact Sciences, Pfizer, Seagen, Lilly, AstraZeneca, MSD, Roche Genentech, BMS, Puma, Orion, Sanofi; Financial Interests, Institutional, Advisory Board, Ad Board: Besins Healthcare; Financial Interests, Institutional, Funding: GE; Financial Interests, Institutional, Invited Speaker, Clinical Research Funding to my Institution: Taiho; Non-Financial Interests, Invited Speaker, Société Française de Sénologie et Pathologie Mammaire: SFSPM. F. André: Financial Interests, Institutional, Research Grant: AstraZeneca, Lilly, Novartis, Pfizer, Roche, Daiichi; Other, Founder: Pegacsy. S. Michiels: Financial Interests, Personal, Other, Statistical advice: IDDI, Amaris, Roche; Financial Interests, Personal, Other, DSMB member: Sensorion, Servier, Biophytis, Yuhan. B. Pistilli: Financial Interests, Institutional, Advisory Role: AstraZeneca, Pfizer, Novartis, AstraZeneca, Daiichi Sankyo; Financial Interests, Personal, Advisory Role: Myriad, Pierre Fabre; Financial Interests, Institutional, Invited Speaker: Daiichi Sankyo, Novartis, Puma; Financial Interests, Personal, Sponsor/Funding: AstraZeneca, Pierre Fabre, MSD. All other authors have declared no conflicts of interest.